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Sample records for hydrated pei layer

  1. Polyethylene oxide hydration in grafted layers

    Science.gov (United States)

    Dormidontova, Elena; Wang, Zilu

    Hydration of water soluble polymers is one of the key-factors defining their conformation and properties, similar to biopolymers. Polyethylene oxide (PEO) is one of the most important biomedical-applications polymers and is known for its reverse temperature solubility due to hydrogen bonding with water. As in many practical applications PEO chains are grafted to surfaces, e.g. of nanoparticles or planar surfaces, it is important to understand PEO hydration in such grafted layers. Using atomistic molecular dynamic simulations we investigate the details of molecular conformation and hydration of PEO end-grafted to gold surfaces. We analyze polymer and water density distribution as a function of distance from the surface for different grafting densities. Based on a detailed analysis of hydrogen bonding between polymer and water in grafted PEO layers, we will discuss the extent of PEO hydration and its implication for polymer conformation, mobility and layer properties. This research is supported by NSF (DMR-1410928).

  2. Electrochemical non-enzyme sensor for detecting clenbuterol (CLB) based on MoS2-Au-PEI-hemin layered nanocomposites.

    Science.gov (United States)

    Yang, Yayun; Zhang, Huan; Huang, Chusen; Yang, Dapeng; Jia, Nengqing

    2017-03-15

    Clenbuterol (CLB), a kind of β2-adrenergic agonists, could disrupt cardiovascular and central nervous system. In this work, a new electrochemical non-enzyme sensor for detecting Clenbuterol (CLB) was fabricated based on MoS2-Au-PEI-hemin layered nanocomposites. The two-dimensional (2-D) MoS2 nanosheets were first in-situ assembled with Au nanoparticles, and polyethylenimine (PEI), then hemin molecules were immobilized onto the MoS2-Au-PEI film-modified glassy carbon electrode (GCE) via amide bond. Scanning electron microscopy (SEM) and Zeta potential measurements were employed to characterize the MoS2-based nanomaterials. Cyclic voltammetry (CV) was used to investigate electrochemical activity of the immobilized hemin on the modified electrode. Upon the optimum conditions, the proposed electrochemical sensor showed an excellent response for CLB including a wide linear ranging from 10ng/mL to 2μg/mL and a detection limit (LOD) of 1.92ng/mL CLB (S/N=3) with favorable reproducibility and stability. Furthermore, this presented method could be feasible for determining CLB in the real pork samples.

  3. Physiological variation of retinal layer thickness is not caused by hydration: a randomised trial.

    Science.gov (United States)

    Balk, Lisanne J; Oberwahrenbrock, Timm; Uitdehaag, Bernard M J; Petzold, Axel

    2014-09-15

    There is evidence for physiological variation of retinal thicknesses as determined by optical coherence tomography (OCT). We tested if such changes could be explained by hydration and would exceed what may be expected from normal ageing. Subjects (n=26) of a previous study were re-assessed and were randomised to 3 groups of a hydration escalation trial (no hydration, 1× hydration, 2× hydration). Automated retinal layer segmentations were performed for the macular retinal nerve fibre layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL) and outer nuclear layer (ONL). The averaged volumes were calculated for the central foveola, 3 mm and 6 mm circles of the ETDRS grid. Following oral hydration there were no significant differences of retinal layer thicknesses between the three randomised groups in any of the ETDRS regions at any time-point. Ageing related changes were significant over an 18 month period for the GCL. The negative outcome of this trial implies that, until the causes for the observed variation are resolved, investigators may need to accept, and include into trial power calculations, a small degree of variation (<1%) of quantitative SD-OCT imaging either due to human physiology or instrument/software related factors.

  4. Energy and Angular Spectra of Albedo Protons and Neutrons Emitted from Hydrated Layers of Lunar Regolith

    Science.gov (United States)

    Townsend, L. W.; Zaman, F.; Schwadron, N. A.; Wilson, J. K.; Spence, H. E.; Case, A. W.; Kasper, J. C.; Mazur, J. E.; Looper, M. D.

    2016-11-01

    Energy and angular yields of albedo protons and neutrons emitted from the lunar surface as a function of hydration layer thickness in the lunar regolith using the MCNP computer code developed at Los Alamos National Laboratory are presented.

  5. Observing the Hydration Layer of Trehalose with a Linked Molecular Terahertz Probe.

    Science.gov (United States)

    Sajadi, Mohsen; Berndt, Falko; Richter, Celin; Gerecke, Mario; Mahrwald, Rainer; Ernsting, Nikolaus P

    2014-06-05

    The terahertz (THz) absorption bands of biomolecular hydration layers are generally swamped by absorption from bulk water. Using the disaccharide trehalose, we show that this limitation can be overcome by attaching a molecular probe. By time-resolving the fluorescence shift of the probe, a local THz spectrum is obtained. From the dependence on temperature and H2O/D2O exchange, it is concluded that the trehalose hydration layer is being observed. The region of dynamic water perturbation by the disaccharide encompasses the probe and is therefore larger than the first two solvation layers.

  6. Synthesis and reversible hydration behavior of the thiosulfate intercalated layered double hydroxide of Zn and Al

    Energy Technology Data Exchange (ETDEWEB)

    Radha, S. [Department of Chemistry, Central College, Bangalore University, Bangalore-560 001 (India); Milius, Wolfgang [Department of Inorganic Chemistry I, University of Bayreuth, Bayreuth (Germany); Breu, Josef, E-mail: josef.breu@uni-bayreuth.de [Department of Inorganic Chemistry I, University of Bayreuth, Bayreuth (Germany); Kamath, P. Vishnu, E-mail: vishnukamath8@hotmail.com [Department of Chemistry, Central College, Bangalore University, Bangalore-560 001 (India)

    2013-08-15

    The thiosulfate-intercalated layered double hydroxide of Zn and Al undergoes reversible hydration with a variation in the relative humidity of the ambient. The hydrated and dehydrated phases, which represent the end members of the hydration cycle, both adopt the structure of the 3R{sub 1} polytype. In the intermediate range of relative humidity values (40–60%), the hydrated and dehydrated phases coexist. The end members of the hydration cycle adopt the structure of the same polytype, and vary only in their basal spacings. This points to the possibility that all the intermediate phases have a kinetic origin. - Graphical abstract: Basal spacing evolution of the thiosulfate ion intercalated [Zn–Al] LDH during one complete hydration–dehydration cycle as a function of relative humidity. Display Omitted - Highlights: • Thiosulfate intercalated [Zn–Al] LDHs were synthesized by co-precipitation. • The LDH exhibits reversible hydration with variation in humidity. • Both the end members of the hydration cycle adopt the same polytype structure. • The interstratified intermediates observed are kinetic in origin.

  7. Hole-doping of mechanically exfoliated graphene by confined hydration layers

    NARCIS (Netherlands)

    Bollmann, Tjeerd Rogier Johannes; Antipina, L.Y.; Temmen, M.; Reichling, M.; Sorokin, P.B.

    2015-01-01

    By the use of non-contact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM), we measure the local surface potential of mechanically exfoliated graphene on the prototypical insulating hydrophilic substrate of CaF2(111). Hydration layers confined between the graphene and the Ca

  8. Hole-doping of mechanically exfoliated graphene by confined hydration layers

    NARCIS (Netherlands)

    Bollmann, T.R.J.; Antipina, L.Y.; Temmen, M.; Reichling, M.; Sorokin, P.B.

    2015-01-01

    By the use of non-contact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM), we measure the local surface potential of mechanically exfoliated graphene on the prototypical insulating hydrophilic substrate of CaF2(111). Hydration layers confined between the graphene and the Ca

  9. Hole-doping of mechanically exfoliated graphene by confined hydration layers

    NARCIS (Netherlands)

    Bollmann, Tjeerd Rogier Johannes; Antipina, L.Y.; Temmen, M.; Reichling, M.; Sorokin, P.B.

    2015-01-01

    By the use of non-contact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM), we measure the local surface potential of mechanically exfoliated graphene on the prototypical insulating hydrophilic substrate of CaF2(111). Hydration layers confined between the graphene and the

  10. Modifying the adsorption properties of anionic surfactants onto hydrophilic silica using the pH dependence of the polyelectrolytes PEI, ethoxylated PEI, and polyamines.

    Science.gov (United States)

    Zhang, Xiaoli; Taylor, Diana; Thomas, Robert; Penfold, Jeffrey; Tucker, Ian

    2011-04-05

    The manipulation of the adsorption of the anionic surfactant, sodium dodecyl sulfate, SDS, onto hydrophilic silica by the polyelectrolytes, polyethyleneimine, PEI, ethoxylated PEI, and the polyamine, pentaethylenehexamine, has been studied using neutron reflectometry. The adsorption of a thin PEI layer onto hydrophilic silica promotes a strong reversible adsorption of the SDS through surface charge reversal induced by the PEI at pH 7. At pH 2.4, a much thicker adsorbed PEI layer is partially swelled by the SDS, and the SDS adsorption is now no longer completely reversible. At pH 10, there is some penetration of SDS and solvent into a thin PEI layer, and the SDS adsorption is again not fully reversible. Ethoxylation of the PEI (PEI-EO(1) and PEI-EO(7)) results in a much weaker and fragile PEI and SDS adsorption at both pH 3 and pH 10, and both polymer and surfactant desorb at higher surfactant concentrations (>critical micellar concentration, cmc). For the polyamine, pentaethylenehexamine, adsorption of a layer of intermediate thickness is observed at pH 10, but at pH 3, no polyamine adsorption is evident; and at both pH 3 and pH 10, no SDS adsorption is observed. The results presented here show that, for the amine-based polyelectrolytes, polymer architecture, molecular weight, and pH can be used to manipulate the surface affinity for anionic surfactant (SDS) adsorption onto polyelectrolyte-coated hydrophilic silica surfaces.

  11. XIAO Pei-gen

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    <正>Academician of Chinese Academy of Engineering Editor-in-chief of Chinese Herbal Medicines(CHM)Honorary director of Institute of Medicinal Plant Development,Chinese Academy of Medical Sciences,Beijing100193,China Tel/Fax:+86-10-62894462 E-mail:xiaopg@public.bta.net.cn Professor XIAO Pei-gen is the founder of the Institute of Medicinal Plant Development(IMPLAD),Chinese Academy of Medical Sciences(CAMS).He is also one of the founders and leading

  12. Hole-doping of mechanically exfoliated graphene by confined hydration layers

    Institute of Scientific and Technical Information of China (English)

    Tjeerd R. J. Bollmann[1,2; Liubov Yu. Antipina[3,4; Matthias Temmen[2; Michael Reichling[2; Pavel B. Sorokin[5

    2015-01-01

    By the use of non-contact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy (KPFM), we measure the local surface potential of mechanically exfoliated graphene on the prototypical insulating hydrophilic substrate of CAF2(111). Hydration layers confined between the graphene and the CaF2 substrate, resulting from the graphene's preparation under ambient conditions on the hydrophilic substrate surface, are found to electronically modify the graphene as the material's electron density transfers from graphene to the hydration layer. Density functional theory (DFT) calculations predict that the first 2 to 3 water layers adjacent to the graphene hole-dope the graphene by several percent of a unit charge per unit cell.

  13. Asymptotic Modelling of Crystallisation in Two Layers Systems. Application to Methane Hydrate Formation in Batch Reactor.

    OpenAIRE

    Cournil, Michel; Herri, Jean-Michel

    2002-01-01

    6 pages; This paper proposes to re-visit the problem of gas-liquid crystallization in the framework of a two-layer model and with the help of data coming from experiments on methane hydrate crystallization in a semi-batch reactor. Preliminary quantitative discussion of the order of magnitude of different effects makes possible realistic simplifications in the theoretical models. In particular, the role of the interfacial film is clearly defined. As previous authors did, we use a formulation i...

  14. Biomimetic hydration lubrication with various polyelectrolyte layers on cross-linked polyethylene orthopedic bearing materials.

    Science.gov (United States)

    Kyomoto, Masayuki; Moro, Toru; Saiga, Kenichi; Hashimoto, Masami; Ito, Hideya; Kawaguchi, Hiroshi; Takatori, Yoshio; Ishihara, Kazuhiko

    2012-06-01

    Natural joints rely on fluid thin-film lubrication by the hydrated polyelectrolyte layer of cartilage. However, current artificial joints with polyethylene (PE) surfaces have considerably less efficient lubrication and thus much greater wear, leading to osteolysis and aseptic loosening. This is considered a common factor limiting prosthetic longevity in total hip arthroplasty (THA). However, such wear could be mitigated by surface modification to mimic the role of cartilage. Here we report the development of nanometer-scale hydrophilic layers with varying charge (nonionic, cationic, anionic, or zwitterionic) on cross-linked PE (CLPE) surfaces, which could fully mimic the hydrophilicity and lubricity of the natural joint surface. We present evidence to support two lubrication mechanisms: the primary mechanism is due to the high level of hydration in the grafted layer, where water molecules act as very efficient lubricants; and the secondary mechanism is repulsion of protein molecules and positively charged inorganic ions by the grafted polyelectrolyte layer. Thus, such nanometer-scaled hydrophilic polymers or polyelectrolyte layers on the CLPE surface of acetabular cup bearings could confer high durability to THA prosthetics.

  15. Formation of hydrated layers in PMMA thin films in aqueous solution

    Energy Technology Data Exchange (ETDEWEB)

    Akers, Peter W. [School of Chemical Sciences, University of Auckland, Auckland (New Zealand); Nelson, Andrew R.J. [The Bragg Institute, Australian Nuclear Science and Technology Organisation, Menai, NSW (Australia); Williams, David E. [School of Chemical Sciences, University of Auckland, Auckland (New Zealand); MacDiarmid Institute of Advanced Materials and Nanotechnology, Wellington (New Zealand); McGillivray, Duncan J., E-mail: d.mcgillivray@auckland.ac.nz [School of Chemical Sciences, University of Auckland, Auckland (New Zealand); MacDiarmid Institute of Advanced Materials and Nanotechnology, Wellington (New Zealand)

    2015-10-30

    Graphical abstract: - Highlights: • Homogeneous thin PMMA films prepared on Si/SiOx substrates and measured in air and water. • Reproducible formation of highly hydrated layer containing 50% water at the PMMA/SiOx interface. • When heated the films swell at 50 °C without loss of material. • Upon re-cooling to 25 °C the surface roughens and material is lost. - Abstract: Neutron reflectometry (NR) measurements have been made on thin (70–150 Å) poly(methylmethacrylate) (PMMA) films on Si/SiOx substrates in aqueous conditions, and compared with parameters measured using ellipsometry and X-Ray reflectometry (XRR) on dry films. All techniques show that the thin films prepared using spin-coating techniques were uniform and had low roughness at both the silicon and subphase interfaces, and similar surface energetics to thicker PMMA films. In aqueous solution, NR measurements at 25 °C showed that PMMA forms a partially hydrated layer at the SiOx interface 10 Å under the film, while the bulk film remains intact and contains around 4% water. Both the PMMA film layer and the sublayer showed minimal swelling over a period of 24 h. At 50 °C, PMMA films in aqueous solution roughen and swell, without loss of PMMA material at the surface. After cooling back to 25 °C, swelling and roughening increases further, with loss of material from the PMMA layer.

  16. Influence of Hydration State on Permeation Testing and Vapor Transport Properties of Protective Clothing Layers

    Directory of Open Access Journals (Sweden)

    Phillip W. Gibson, Ph.D

    2009-12-01

    Full Text Available Protective clothing systems composed ofpermselective polymer film laminates are analternative to standard air-permeable garments basedon activated carbon. These polymer layers aredesigned with high water vapor permeation rates andlow permeation of chemical warfare agents. Polymerfilms that have a significant water vapor flux usuallyalso have an affinity for water, and will hydrate andswell significantly at high humidity levels. Thepolymer film’s increase in water content has thepotential to affect the transport rate of chemicalwarfare agents in vapor and liquid form, and usuallyalso has a large effect on the intrinsic water vaporpermeability of the membrane.

  17. Distinguishing dynamical features of water inside protein hydration layer: Distribution reveals what is hidden behind the average

    Science.gov (United States)

    Mukherjee, Saumyak; Mondal, Sayantan; Bagchi, Biman

    2017-07-01

    Since the pioneering works of Pethig, Grant, and Wüthrich on a protein hydration layer, many studies have been devoted to find out if there are any "general and universal" characteristic features that can distinguish water molecules inside the protein hydration layer from bulk. Given that the surface itself varies from protein to protein, and that each surface facing the water is heterogeneous, search for universal features has been elusive. Here, we perform an atomistic molecular dynamics simulation in order to propose and demonstrate that such defining characteristics can emerge if we look not at average properties but the distribution of relaxation times. We present results of calculations of distributions of residence times and rotational relaxation times for four different protein-water systems and compare them with the same quantities in the bulk. The distributions in the hydration layer are unusually broad and log-normal in nature due to the simultaneous presence of peptide backbones that form weak hydrogen bonds, hydrophobic amino acid side chains that form no hydrogen bond, and charged polar groups that form a strong hydrogen bond with the surrounding water molecules. The broad distribution is responsible for the non-exponential dielectric response and also agrees with large specific heat of the hydration water. Our calculations reveal that while the average time constant is just about 2-3 times larger than that of bulk water, it provides a poor representation of the real behaviour. In particular, the average leads to the erroneous conclusion that water in the hydration layer is bulk-like. However, the observed and calculated lower value of static dielectric constant of hydration layer remained difficult to reconcile with the broad distribution observed in dynamical properties. We offer a plausible explanation of these unique properties.

  18. Tuning the field-induced magnetic transition in a layered cobalt phosphonate by reversible dehydration-hydration process.

    Science.gov (United States)

    Yang, Ting-Hai; Liao, Yi; Zheng, Li-Min; Dinnebier, Robert E; Su, Yan-Hui; Ma, Jing

    2009-06-07

    A layered cobalt phosphonate, Co(2-pmp)(H(2)O)(2) (1) (2-pmpH(2) = 2-pyridylmethylphosphonic acid) is reported, which provides the first example of metamagnetic cobalt system that shows reversible changes in both structures and magnetic behaviors upon dehydration-hydration process.

  19. A hydrated phospholipid polymer-grafted layer prevents lipid-related oxidative degradation of cross-linked polyethylene.

    Science.gov (United States)

    Kyomoto, Masayuki; Moro, Toru; Yamane, Shihori; Takatori, Yoshio; Tanaka, Sakae; Ishihara, Kazuhiko

    2017-01-01

    The surface and substrate of a cross-linked polyethylene (CLPE) liner are designed to achieve resistance against oxidative degradation in the construction of hip joint replacements. In this study, we aimed to evaluate the oxidative degradation caused by lipid absorption of a highly hydrophilic nanometer-scaled thickness layer prepared by grafting a poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) layer and a high-dose gamma-ray irradiated CLPE with vitamin E blending (HD-CLPE[VE]). The HD-CLPE(VE) and PMPC-grafted HD-CLPE(VE) exhibited extremely high oxidation resistance regardless of lipid absorption, even though residual-free radical levels were detectable. The water wettability of the PMPC-grafted CLPE and PMPC-grafted HD-CLPE(VE) surfaces was considerably greater than that of untreated surfaces. The hydrated PMPC-grafted layer also exhibited extremely low solubility for squalene. Lipids such as squalene and cholesterol esters diminished the oxidation resistance of CLPE despite the vitamin E improvement. Notably, the PMPC-grafted surface was resistant to lipid absorption and diffusion as well as subsequent lipid-related oxidative degradation, likely because of the presence of the hydrated PMPC-grafted layer. Together, these results provide preliminary evidence that the resistance against lipid absorption and diffusion of a hydrated PMPC-grafted layer might positively affect the extent of resistance to the in vivo oxidation of orthopedic implants.

  20. Conceptual Tenets of the Theory of Hydration of Heterogeneous Surface with Polar Order of Disperse Ground Layers of Sedimentary Genesis

    Directory of Open Access Journals (Sweden)

    Tamara G. Makeeva

    2012-09-01

    Full Text Available The article, basing on the established regularity defines the basic tenets of the theory of hydration of heterogeneous surface with polar order of disperse ground layers of sedimentary genesis. It offers classification and formula for the associated water density, valid corrections for the associated water density, calculates the water film thickness in disperse ground, develops the reliable physicochemical model of the disperse ground, determines the range of applicability of the existing laboratory and field methods.

  1. Perturbation of hydration layer in solvated proteins by external electric and electromagnetic fields: Insights from non-equilibrium molecular dynamics

    Science.gov (United States)

    Nandi, Prithwish K.; Futera, Zdenek; English, Niall J.

    2016-11-01

    Given the fundamental role of water in governing the biochemistry of enzymes, and in regulating their wider biological activity (e.g., by local water concentration surrounding biomolecules), the influence of extraneous electric and electromagnetic (e/m) fields thereon is of central relevance to biophysics and, more widely, biology. With the increase in levels of local and atmospheric microwave-frequency radiation present in modern life, as well as other electric-field exposure, the impact upon hydration-water layers surrounding proteins, and biomolecules generally, becomes a particularly pertinent issue. Here, we present a (non-equilibrium) molecular-dynamics-simulation study on a model protein (hen egg-white lysozyme) hydrated in water, in which we determine, inter alia, translational self-diffusivities for both hen egg-white lysozyme and its hydration layer together with relaxation dynamics of the hydrogen-bond network between the protein and its hydration-layer water molecules on a residue-per-residue basis. Crucially, we perform this analysis both above and below the dynamical-transition temperature (at ˜220 K), at 300 and 200 K, respectively, and we compare the effects of external static-electric and e/m fields with linear-response-régime (r.m.s.) intensities of 0.02 V/Å. It was found that the translational self-diffusivity of hen egg-white lysozyme and its hydration-water layer are increased substantially in static fields, primarily due to the induced electrophoretic motion, whilst the water-protein hydrogen-bond-network-rearrangement kinetics can also undergo rather striking accelerations, primarily due to the enhancement of a larger-amplitude local translational and rotational motion by charged and dipolar residues, which serves to promote hydrogen-bond breakage and re-formation kinetics. These external-field effects are particularly evident at 200 K, where they serve to induce the protein- and solvation-layer-response effects redolent of dynamical

  2. Molecular Dynamics Simulation of Atomic Force Microscopy at the Water-Muscovite Interface: Hydration Layer Structure and Force Analysis.

    Science.gov (United States)

    Kobayashi, Kazuya; Liang, Yunfeng; Amano, Ken-ichi; Murata, Sumihiko; Matsuoka, Toshifumi; Takahashi, Satoru; Nishi, Naoya; Sakka, Tetsuo

    2016-04-19

    With the development of atomic force microscopy (AFM), it is now possible to detect the buried liquid-solid interfacial structure in three dimensions at the atomic scale. One of the model surfaces used for AFM is the muscovite surface because it is atomically flat after cleavage along the basal plane. Although it is considered that force profiles obtained by AFM reflect the interfacial structures (e.g., muscovite surface and water structure), the force profiles are not straightforward because of the lack of a quantitative relationship between the force and the interfacial structure. In the present study, molecular dynamics simulations were performed to investigate the relationship between the muscovite-water interfacial structure and the measured AFM force using a capped carbon nanotube (CNT) AFM tip. We provide divided force profiles, where the force contributions from each water layer at the interface are shown. They reveal that the first hydration layer is dominant in the total force from water even after destruction of the layer. Moreover, the lateral structure of the first hydration layer transcribes the muscovite surface structure. It resembles the experimentally resolved surface structure of muscovite in previous AFM studies. The local density profile of water between the tip and the surface provides further insight into the relationship between the water structure and the detected force structure. The detected force structure reflects the basic features of the atomic structure for the local hydration layers. However, details including the peak-peak distance in the force profile (force-distance curve) differ from those in the density profile (density-distance curve) because of disturbance by the tip.

  3. On the lipid head group hydration of floating surface monolayers bound to self-assembled molecular protein layers

    DEFF Research Database (Denmark)

    Lösche, M.; Erdelen, C.; Rump, E.

    1994-01-01

    with molecular resolution. Emphasis here is placed on the hydration of the lipid head groups in the bound state. For three functionalized lipids with spacers of different lengths between the biotin and their chains it was observed that the head groups were dehydrated in monolayers of the pure lipids, which were...... kept at low surface pressure before protein adsorption. The introduction of dipole moments at the interface by the admixture of phospholipids or the application of lateral pressure on the lipid monolayer before protein adsorption were found to impose an extension of the spacer moieties. The biotin...... groups were thus presented further away from the interface, and a hydration layer between the protein and the functionalized interface was observed in the self-assembled supramolecular structures....

  4. NMR Spectroscopy of the Hydrated Layer of Composite Particles Based on Nanosized Al2O3 and Vitreous Humor

    Science.gov (United States)

    Turov, V. V.; Gerashchenko, I. I.; Markina, A. I.

    2013-11-01

    The hydrated layer of composite particles prepared using Al2O3 and cattle vitreous humor was investigated using NMR spectroscopy. It was found that water bound to Al2O3 nanoparticles was present in the form of clusters with different degrees of association and energies of interaction with the surface. Water bound to the surface of the Al2O3/vitreous humor composite became more uniform upon immobilization of vitreous humor components on the surface of the Al2O3. With this, the clusters of adsorbed water had characteristics that were close to those found in air and weakly polar CHCl3 media. Addition of polar CH3CN led to the formation of very small water clusters. PMR spectra of the surface of the Al2O3/vitreous humor composite in the presence of trifluoroacetic acid differentiated four types of hydrated structures that differed in the degree of water association.

  5. Hydrogen bond network in the hydration layer of the water confined in nanotubes increasing the dielectric constant parallel along the nanotube axis

    Science.gov (United States)

    Qi, Wenpeng; Zhao, Hongwei

    2015-09-01

    The water confined in nanotubes has been extensively studied, because of the potential usages in drug delivery and desalination. The radial distribution of the dielectric constant parallel along the nanotube axis was obtained by molecular dynamics simulations in a carbon nanotube and a nanotube with a very small van der Waals potential. The confined water was divided into two parts, the middle part water and the hydration water. In both cases, the hydrogen bond orientation of the middle water is isotropic, while the hydrogen bonds in hydration layers are apt to parallel along the nanotube axis. Therefore, the hydration water has higher dipole correlations increasing the dielectric constant along the nanotube axis.

  6. Hydrogen bond network in the hydration layer of the water confined in nanotubes increasing the dielectric constant parallel along the nanotube axis.

    Science.gov (United States)

    Qi, Wenpeng; Zhao, Hongwei

    2015-09-21

    The water confined in nanotubes has been extensively studied, because of the potential usages in drug delivery and desalination. The radial distribution of the dielectric constant parallel along the nanotube axis was obtained by molecular dynamics simulations in a carbon nanotube and a nanotube with a very small van der Waals potential. The confined water was divided into two parts, the middle part water and the hydration water. In both cases, the hydrogen bond orientation of the middle water is isotropic, while the hydrogen bonds in hydration layers are apt to parallel along the nanotube axis. Therefore, the hydration water has higher dipole correlations increasing the dielectric constant along the nanotube axis.

  7. 姜黄素-甘草次酸-PEI-PLGA 纳米粒的制备及工艺优化%Preparation of curcumin-glycyrrhetinic acid-PEI-PLGA nanoparticles and the process optimization

    Institute of Scientific and Technical Information of China (English)

    胡慧中; 郑晓君; 胡巧红

    2015-01-01

    Objective To prepare curcumin (Cur)-glycyrrhetinic acid (GA)-PEI-PLGA nanoparticles and optimize the preparation process .Methods Cur-GA-PEI-PLGA nanoparticles were prepared by thin film hydration method .After establishing the analysis method , single factor experiment and orthogonal design experiment were used to evaluate the effects of hydration temperature , hydration time and drug addition on the entrapment efficiency and drug loading , and to determine the optimum preparation conditions .Cur-GA-PEI-PLGA nanoparticles were prepared under the optimum preparation condi-tions , and we determined the entrapment efficiency and drug loading .The morphology of the nanoparticles was observed by transmission electron microscope (TEM).The diameter and zeta potential of the nanoparticles were determined by dynamic light scattering particle size analyzer ( DLS) .Results The optimum preparation conditions of Cur-GA-PEI-PLGA nanopar-ticles were as follows:the hydration temperature was 60 ℃, the hydration time was 3 h, and the drug addition was 7 mg. The entrapment efficiency and drug loading were (58.1 ±1.2)%and (14.5 ±1.4)%under these conditions .The nanop-articles were spherical and uniform under TEM .The average particle size was 330.3 nm, and the nanoparticles distributed evenly (PDI was 0.311), zeta potential was 39.2 mV.Conclusions Thin film hydration method is suitable for the prepa-ration of Cur-GA-PEI-PLGA nanoparticles .The optimum preparation conditions are as follows:the hydration temperature is 60 ℃, the hydration time is 3 h, and the drug addition is 7 mg.%目的:制备姜黄素(Cur)-甘草次酸(GA)-PEI-PLGA纳米粒,并优化其制备工艺。方法采用薄膜水化法制备Cur-GA-PEI-PLGA纳米粒,建立分析方法后,采用单因素和正交设计试验考察水化温度、水化时间、投药量对纳米粒包封率和载药量的影响,确定最佳制备条件。在最佳条件下制备Cur-GA-PEI-PLGA纳米粒,检测其包

  8. A New n = 4 Layered Ruddlesden-Popper Phase K(2.5)Bi(2.5)Ti4O13 Showing Stoichiometric Hydration.

    Science.gov (United States)

    Liu, Samuel; Avdeev, Maxim; Liu, Yun; Johnson, Mark R; Ling, Chris D

    2016-02-15

    A new bismuth-containing layered perovskite of the Ruddlesden-Popper type, K(2.5)Bi(2.5)Ti4O13, has been prepared by solid-state synthesis. It has been shown to hydrate to form stoichiometric K(2.5)Bi(2.5)Ti4O13·H2O. Diffraction data show that the structure consists of a quadruple-stacked (n = 4) perovskite layer, with potassium ions occupying the rock salt layer and its next-nearest A site. The hydrated sample was shown to remove the offset between stacked perovskite layers relative to the dehydrated sample. Computational methods show that the hydrated phase consists of intact H2O molecules in a vertical "pillared" arrangement bridging across the interlayer space. Rotations of H2O molecules about the c axis were evident in molecular dynamic calculations, which increased in rotation angle with increasing temperature. In situ diffraction data for the dehydrated phase point to a broad structural phase transition from orthorhombic to tetragonal at ∼600 °C. The relative bismuth-rich composition in the perovskite block results in a higher transition temperature compared to related perovskite structures. Water makes a significant contribution to the dielectric constant, which disappears after dehydration.

  9. Combining gravimetric and vibrational spectroscopy measurements to quantify first- and second-shell hydration layers in polyimides with different molecular architectures.

    Science.gov (United States)

    Musto, Pellegrino; Mensitieri, Giuseppe; Lavorgna, Marino; Scarinzi, Gennaro; Scherillo, Giuseppe

    2012-02-02

    In-situ Fourier transform infrared (FTIR) measurements have been carried out at different relative pressures of water vapor to study the H(2)O diffusion in three polyimides differing in their molecular structure and fluorine substitution. Spectral data have been analyzed by difference spectroscopy, least-squares curve fitting, and two-dimensional (2D) correlation spectroscopy, which provided molecular level information on the diffusion mechanism. In particular, two distinct water species were identified corresponding, respectively, to the first and second-shell hydration layers. The spectroscopic analysis demonstrated that the relative population of these species is a function of the total water content in the system. A method has been devised to quantify the water concentration in the two hydration layers, based on a combination of spectroscopic and gravimetric data. The results have been compared with those from an earlier spectroscopic approach reported in the literature and based on the analysis of the carbonyl region.

  10. Origins of hydration lubrication.

    Science.gov (United States)

    Ma, Liran; Gaisinskaya-Kipnis, Anastasia; Kampf, Nir; Klein, Jacob

    2015-01-14

    Why is friction in healthy hips and knees so low? Hydration lubrication, according to which hydration shells surrounding charges act as lubricating elements in boundary layers (including those coating cartilage in joints), has been invoked to account for the extremely low sliding friction between surfaces in aqueous media, but not well understood. Here we report the direct determination of energy dissipation within such sheared hydration shells. By trapping hydrated ions in a 0.4-1 nm gap between atomically smooth charged surfaces as they slide past each other, we are able to separate the dissipation modes of the friction and, in particular, identify the viscous losses in the subnanometre hydration shells. Our results shed light on the origins of hydration lubrication, with potential implications both for aqueous boundary lubricants and for biolubrication.

  11. Enhanced corrosion protective PANI-PAA/PEI multilayer composite coatings for 316SS by spin coating technique

    Energy Technology Data Exchange (ETDEWEB)

    Syed, Junaid Ali; Lu, Hongbin; Tang, Shaochun; Meng, Xiangkang, E-mail: mengxk@nju.edu.cn

    2015-01-15

    Highlights: • PANI-PAA/PEI multilayers with controllable thickness were fabricated by spin assembly. • PAA matrix results in the homogeneous dispersion of PANI in the composite coatings. • Spin coating combined with heating assures the linear increase in thickness with n. • The corrosion protection property of PANI-PAA/PEI coatings were optimized at n = 20. • Enhanced protection owing to multilayer structure that lengthens the diffusion pathway of ions. - Abstract: In the present study, polyaniline-polyacrylic acid/polyethyleneimine (PANI-PAA/PEI) composite coatings with a multilayer structure for corrosion protection of 316 stainless steels (316SS) were prepared by an alternate deposition. Spin coating combined with heating assists removal of residual water that result in a linear increase in thickness with layer number (n). The combination of PANI-PAA composite with PEI and their multilayer structure provides a synergistic enhancement of corrosion resistance properties as determined by electrochemical measurements in 3.5% NaCl solution. Importantly, the PANI-PAA/PEI coating with an optimized layer number of n = 20 shows improved corrosion protection. The superior performance was attributed to the formation of an interfacial oxide layer as well as the multilayer structure that extend the diffusion pathway of corrosive ions.

  12. The Effect of Linear PEI on Characteristics and Transfection Efficiency of PEI-Based Cationic Nanoliposomes

    Directory of Open Access Journals (Sweden)

    Mohammad Ramezani

    2011-01-01

    Full Text Available Objective(sThe development of efficient and safe carrier system to transfer DNA into cells is essential in non-viral gene therapy. The aim of the present study was to evaluate the effect of linear polyetheneimine (lPEI (2500 Da on the physicochemical and biological properties of lipopolyplexes constructed from liposomes and lPEI. Materials and MethodsDifferent lipopolymers were synthesized from lPEI and acrylate derivatives. Nanocarriers were composed of the lipids (DOPE, DPPE and DOTAP and the synthesized lipopolymers. After characterization of the prepared vectors by determination of size and zeta potential, transfection activity was tested in Neuro2A cells. Ethidium bromide and MTT test were used to evaluate the DNA condensation ability and cytotoxicity of vectors, respectively. Results Vector’s size ranged from 95 to 337 nm and they had positive charge. The differences in DNA binding properties of lipopolyplexes were not significant. Among lipids, DOTAP showed better impact on transfection efficiency. The highest transfection activity was achieved by liposomal formulation consist of DOTAP and lipopolymer composed of lPEI and hexyl acrylate. The lipopolyplexes showed minimum cytotoxicity to the cultured cells in vitro. Conclusion The results of study confirmed that it is possible to improve gene expression using lipopolyplexes.

  13. The effect of hydration layers on the anodic growth and on the dielectric properties of Al{sub 2}O{sub 3} for electrolytic capacitors

    Energy Technology Data Exchange (ETDEWEB)

    Scaduto, G., E-mail: scaduto_giuseppe@libero.it [Electrochemical Material Science Laboratory, Facoltà di Ingegneria, Università di Palermo, Viale delle Scienze, Ed. 6, 90128 Palermo (Italy); Santamaria, M., E-mail: monica.santamaria@unipa.it [Electrochemical Material Science Laboratory, Facoltà di Ingegneria, Università di Palermo, Viale delle Scienze, Ed. 6, 90128 Palermo (Italy); Bocchetta, P., E-mail: patrizia.bocchetta@unisalento.it [Dipartimento di Ingegneria dell' Innovazione, Università del Salento, via Monteroni, 73100 Lecce (Italy); Di Quarto, F., E-mail: francesco.diquarto@unipa.it [Electrochemical Material Science Laboratory, Facoltà di Ingegneria, Università di Palermo, Viale delle Scienze, Ed. 6, 90128 Palermo (Italy)

    2014-01-01

    Hydrous films were grown on high purity and cubicity Al foils for electrolytic capacitors in deionized water, ethylene glycol–deionized water and glycerol–deionized water at different immersion times. According to X-ray diffraction patterns the hydration treatment allowed growing a pseudo boehmite layer on Al surface whose morphology is appreciably affected by the bath composition. Capacitance measurements and photoelectrochemical findings suggest that a more compact barrier layer forms during the immersion in alcohol containing solutions. The hydration in water allowed saving energy and preparing more blocking oxide films. The beneficial effect of hydration in hot water on the specific capacitance was evidenced only for films formed at 300 V due to the crystallization of amorphous alumina in γ′-Al{sub 2}O{sub 3}. - Highlights: • Hydrous films were grown on Al foils in hot H{sub 2}O and alcohol–H{sub 2}O mixtures. • Hydrous films' solid state properties were studied as a function of growing condition. • Hydrous films sensitively influence charge consumption during anodizing process. • Hydrous films sensitively influence dielectric properties of anodic Al{sub 2}O{sub 3}.

  14. Confined Water in Layered Silicates: The Origin of Anomalous Thermal Expansion Behavior in Calcium-Silicate-Hydrates.

    Science.gov (United States)

    Krishnan, N M Anoop; Wang, Bu; Falzone, Gabriel; Le Pape, Yann; Neithalath, Narayanan; Pilon, Laurent; Bauchy, Mathieu; Sant, Gaurav

    2016-12-28

    Water, under conditions of nanoscale confinement, exhibits anomalous dynamics, and enhanced thermal deformations, which may be further enhanced when such water is in contact with hydrophilic surfaces. Such heightened thermal deformations of water could control the volume stability of hydrated materials containing nanoconfined structural water. Understanding and predicting the thermal deformation coefficient (TDC, often referred to as the CTE, coefficient of thermal expansion), which represents volume changes induced in materials under conditions of changing temperature, is of critical importance for hydrated solids including: hydrogels, biological tissues, and calcium silicate hydrates, as changes in their volume can result in stress development, and cracking. By pioneering atomistic simulations, we examine the physical origin of thermal expansion in calcium-silicate-hydrates (C-S-H), the binding agent in concrete that is formed by the reaction of cement with water. We report that the TDC of C-S-H shows a sudden increase when the CaO/SiO2 (molar ratio; abbreviated as Ca/Si) exceeds 1.5. This anomalous behavior arises from a notable increase in the confinement of water contained in the C-S-H's nanostructure. We identify that confinement is dictated by the topology of the C-S-H's atomic network. Taken together, the results suggest that thermal deformations of hydrated silicates can be altered by inducing compositional changes, which in turn alter the atomic topology and the resultant volume stability of the solids.

  15. Minxin Pei, China's Crony Capitalism: The Dynamics of Regime Decay

    DEFF Research Database (Denmark)

    Brødsgaard, Kjeld Erik

    2017-01-01

    Book review of: Minxin Pei, China's Crony Capitalism: The Dynamics of Regime Decay. Cambridge, Mass.: Harvard University Press, 2016. 365 pp., including references and index. ISBN 9780674737297.......Book review of: Minxin Pei, China's Crony Capitalism: The Dynamics of Regime Decay. Cambridge, Mass.: Harvard University Press, 2016. 365 pp., including references and index. ISBN 9780674737297....

  16. Formation of porous gas hydrates

    CERN Document Server

    Salamatin, Andrey N

    2015-01-01

    Gas hydrates grown at gas-ice interfaces are examined by electron microscopy and found to have a submicron porous texture. Permeability of the intervening hydrate layers provides the connection between the two counterparts (gas and water molecules) of the clathration reaction and makes further hydrate formation possible. The study is focused on phenomenological description of principal stages and rate-limiting processes that control the kinetics of the porous gas hydrate crystal growth from ice powders. Although the detailed physical mechanisms involved in the porous hydrate formation still are not fully understood, the initial stage of hydrate film spreading over the ice surface should be distinguished from the subsequent stage which is presumably limited by the clathration reaction at the ice-hydrate interface and develops after the ice grain coating is finished. The model reveals a time dependence of the reaction degree essentially different from that when the rate-limiting step of the hydrate formation at...

  17. IEOH MING PEI: UNA IDEA, TRES VARIACIONES

    Directory of Open Access Journals (Sweden)

    Alberto Donaire Rodríguez

    2010-05-01

    Full Text Available RESUMEN El texto siguiente es un resumen de mi lección de despedida, el 18 de noviembre de 2006, al jubilarme en la Escuela de Arquitectura de Sevilla. Como no se grabó y nunca llevo escritas mis clases, ésta es una reconstrucción basada en mi guión y en las notas tomadas por algunos asistentes, a los que agradezco su interés.Por vez primera se celebraba en la Escuela un acto de esta naturaleza, por iniciativa del entonces Director, Jaime Navarro Casas. A él agradezco su presencia y sus palabras, e igualmente a Juan Luis Trillo de Leyva, que hizo una especie de recorrido sentimental de mi paso por la Escuela, que escuché con emoción. En el mismo curso dieron luego su lección de despedida dos profesores que han dejado en nosotros honda huella, Rafael Manzano y José Luis Manzanares. Estos actos son un bello colofón de una carrera académica.La clase fue una reflexión sobre la arquitectura, al hilo del comentario de tres obras del arquitecto Ieoh Ming Pei en tres ciudades diferentes: las ampliaciones de la National Gallery de Washington, del Museo del Louvre de París y del Deutsches Historisches Museum de Berlín.SUMMARY The following text is a summary of my valedictory lecture, on 18 November 2006, on my retirement from the School of Architecture of Seville. As it was not recorded, and my never having written up my classes, this is a reconstruction based on my outline and the notes taken by some of those present, whom I thank for their interest.This was the first time an act of this nature was held in the School, on the initiative of the then Director, Jaime Navarro Casas. I thank him for his presence and his words, and also Juan Luis Trillo de Leyva, who made a sort of sentimental journey of my time at the School, to which I listened with emotion. Later, valedictory lectures were given by two teachers who have left a profound imprint on us, Rafael Manzano and José Luis Manzanares. These acts are a beautiful conclusion to an

  18. ON APPLICATION OF MATERIALS BASED ON DISPERSE HYDRATED CALCIUM SILICATE FOR PROTECTIVE LAYER OF LOCAL AUTOMOBILE ROADS

    Directory of Open Access Journals (Sweden)

    V. N. Yaglov

    2016-01-01

    Full Text Available Road construction is one of the most material-intensive industrial production. In this context, the urgent task for this branch is the maximum reduction in consumption of materials through usage of effective local materials, decrease energy intensity of processes by using new materials. The developed network of local roads require constant care and maintenance, thus it is advisable to consider the use of protective coatings for such roads on the basis of contactcondensation hardening, which can be obtained on the basis of local raw materials. One of the representatives of such material is disperse hydrated calcium silicate, which found wide practical application as the main components in the production of building materials, glass, glass ceramics and ceramic products. For example, relatively cheap highly dispersed crystalline material is intermediate product of hydrochemical synthesis of wollastonite xonotlite Ca6(Si6O17(OH2. A variety of calcium and silicon-containing raw materials, suitable to obtain various types hydrated calcium silicate, as well as increasing requirements for physical and chemical properties, caused by actuality of problems of search and study the best ways of synthesis hydrated calcium silicate from man-made and natural materials. The theoretical basis of the proposed technology for material production for road pavement lower categories is the ability of silicate dispersed materials transferred in an unstable state, forming a rock-like waterproof body at the time of application of mechanical load. Disperse hydrated calcium silicate are the most typical representatives of contactcondensation hardening binders. It should be noted that the technology of obtaining these binders is not related to high-temperature processes and the synthesis of HCS realized when wet treatment of available cheap raw materials on the standard equipment, what determines their practical significance.

  19. QCM Sensors Based on PEI Films for CO2Detection

    Institute of Scientific and Technical Information of China (English)

    Guang-Zhong Xie; Ting Kang; Yong Zhou; Tao Xie; Hui-Ling Tai; Ya-Dong Jiang

    2015-01-01

    In this paper, quartz crystal microbalance (QCM) gas sensors coated with polyehtyleneimine (PEI) was utilized for carbon dioxide (CO2) detection. The sensing mechanism is based on the availability of reversible acid-base reactions between CO2 molecules and PEI at room temperature. The experimental results revealed that the PEI/starch sensor exhibited much higher sensitivity than that of pure PEI, and showed approximate linearity over a concentration region ranging from 500ppm to 8000ppm. The influence of humidity had also been investigated. Furthermore, the response and recovery time deceased as the operation temperatures increased. Finally, sensitivity loss after conservation for several days and reversibility of the sensors had been discussed.

  20. Comparison of PEI-PEG and PLL-PEG copolymer coatings on the prevention of protein fouling.

    Science.gov (United States)

    Bergstrand, Anna; Rahmani-Monfared, Ghazal; Ostlund, Asa; Nydén, Magnus; Holmberg, Krister

    2009-03-01

    The effect of surface charge on the protein resistance of adsorbed layers of poly(ethylene imine)-[g]-poly(ethylene glycol), PEI-PEG, and poly(L-lysine)-[g]-poly(ethylene glycol), PLL-PEG, was studied. Mixed and monofunctional self-assembled monolayers, SAMs, on gold were obtained by adsorption of 16-mercapto-1-hexadecanoic acid and 16-mercapto-1-hexadecanol. The surface charge was systematically varied by changing the ratio of the two alkanethiols. The graft copolymers PEI-PEG and PLL-PEG were adsorbed at the SAMs and tested for resistance towards human serum albumin and fibrinogen. The adsorbed amount of copolymers increased with increasing negative surface charge. However, the best protein resistance was found at an intermediate surface charge. The PLL-PEG covered surfaces showed better protein resistance than the PEI-PEG covered surfaces. Thus, this work demonstrates that an adsorbed layer of PEG-grafted PEI and, in particular, PEG-grafted PLL is efficient in preventing protein adsorption when there is charge neutralization between the copolymer and the underlying surface. (c) 2008 Wiley Periodicals, Inc.

  1. Optimization of conditions for gene delivery system based on PEI

    Directory of Open Access Journals (Sweden)

    Roya Cheraghi

    2017-01-01

    Full Text Available Objective(s: PEI based nanoparticle (NP due to dual capabilities of proton sponge and DNA binding is known as powerful tool for nucleic acid delivery to cells. However, serious cytotoxicity and complicated conditions, which govern NPs properties and its interactions with cells practically, hindered achievement to high transfection efficiency. Here, we have tried to optimize the properties of PEI/ firefly luciferase plasmid complexes and cellular condition to improve transfection efficiency. Materials and Methods: For this purpose, firefly luciferase, as a robust gene reporter, was complexed with PEI to prepare NPs with different size and charge. The physicochemical properties of nanoparticles were evaluated using agarose gel retardation and dynamic light scattering.  MCF7 and BT474 cells at different confluency were also transfected with prepared nanoparticles at various concentrations for short and long times. Results: The branched PEI can instantaneously bind to DNA and form cationic NPs. The results demonstrated the production of nanoparticles with size about 100-500 nm dependent on N/P ratio. Moreover, increase of nanoparticles concentration on the cell surface drastically improved the transfection rate, so at a concentration of 30 ng/ìl, the highest transfection efficiency was achieved. On the other side, at confluency between 40-60%, the maximum efficiency was obtained. The result demonstrated that N/P ratio of 12 could establish an optimized ratio between transfection efficiency and cytotoxicity of PEI/plasmid nanoparticles. The increase of NPs N/P ratio led to significant cytotoxicity. Conclusion: Obtained results verified the optimum conditions for PEI based gene delivery in different cell lines.

  2. Synthesizing Iron Oxide Nanostructures: The Polyethylenenemine (PEI Role

    Directory of Open Access Journals (Sweden)

    Sergio Lentijo Mozo

    2017-01-01

    Full Text Available Controlled synthesis of anisotropic iron oxide nanoparticles is a challenge in the field of nanomaterial research that requires an extreme attention to detail. In particular, following up a previous work showcasing the synthesis of magnetite nanorods (NRs using a two-step approach that made use of polyethylenenemine (PEI as a capping ligand to synthesize intermediate β-FeOOH NRs, we studied the effect and influence of the capping ligand on the formation of β-FeOOH NRs. By comparing the results reported in the literature with those we obtained from syntheses performed (1 in the absence of PEI or (2 by using PEIs with different molecular weight, we showed how the choice of different PEIs determines the aspect ratio and the structural stability of the β-FeOOH NRs and how this affects the final products. For this purpose, a combination of XRD, HRTEM, and direct current superconducting quantum interference device (DC SQUID magnetometry was used to identify the phases formed in the final products and study their morphostructural features and related magnetic behavior.

  3. Synthesizing Iron Oxide Nanostructures: The Polyethylenenemine (PEI) Role

    KAUST Repository

    Mozo, Sergio Lentijo

    2017-01-12

    Controlled synthesis of anisotropic iron oxide nanoparticles is a challenge in the field of nanomaterial research that requires an extreme attention to detail. In particular, following up a previous work showcasing the synthesis of magnetite nanorods (NRs) using a two-step approach that made use of polyethylenenemine (PEI) as a capping ligand to synthesize intermediate β-FeOOH NRs, we studied the effect and influence of the capping ligand on the formation of β-FeOOH NRs. By comparing the results reported in the literature with those we obtained from syntheses performed (1) in the absence of PEI or (2) by using PEIs with different molecular weight, we showed how the choice of different PEIs determines the aspect ratio and the structural stability of the β-FeOOH NRs and how this affects the final products. For this purpose, a combination of XRD, HRTEM, and direct current superconducting quantum interference device (DC SQUID) magnetometry was used to identify the phases formed in the final products and study their morphostructural features and related magnetic behavior.

  4. Morphological characterization of nanocomposites of membrane PEI/regional clay; Caracterizacao morfologica de membranas de nanocompositos de PEI/argila regional

    Energy Technology Data Exchange (ETDEWEB)

    Medeiros, Vanessa da N.; Leite, Amanda M.D.; Paz, Rene A. da; Araujo, Edcleide M., E-mail: vanismedeiros@gmail.com [Dept. de Engenharia de Materiais, Universidade Federal de Campina Grande - UFCG, Campina Grande, PB (Brazil); Pessan, Luiz A. [Universidade Federal de Sao Carlos - UFSCar, Sao Carlos, SP (Brazil)

    2011-07-01

    The interest in the nanotechnology development in the last decade allows the increase in the nanocomposite area due to the special properties presented by these materials. In the nanocomposite, the nanometric particles are dispersed in the polymer matrix. The membrane separation process, although is recently, is increasing in applications such as purification, fractioning and concentration of substances in several industries. The membranes to gas separation present specific advantages when compared with conventional separation process (such as, cryogenic distillation and adsorption). The aim of this work is to prepare plane membrane by evaporation-precipitation method. These membranes were obtained from polyetherimide (PEI) with bentonite clay from Paraiba/Brazil. The results showed that by XRD, it can be observed there is not practically intercalation of polymer molecules between the layers of clay and was seen by SEM that the membranes have dense structures, ie, favorable for application in gas separation. (author)

  5. CO2 Adsorption to Sub-Single Hydration Layer Montmorillonite Clay Studied by Excess Sorption and Neutron Diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Rother, Gernot [ORNL; Ilton, Eugene [Pacific Northwest National Laboratory (PNNL); Wallacher, Dirk [Helmholtz-Zentrum Berlin; Hauss, Thomas [Helmholtz-Zentrum Berlin; Schaef, Herbert [Pacific Northwest National Laboratory (PNNL); Qafoku, Odeta [Pacific Northwest National Laboratory (PNNL); Rosso, Kevin M. [Pacific Northwest National Laboratory (PNNL); Felmy, Andrew [Pacific Northwest National Laboratory (PNNL); Krukowski, Elizabeth G [ORNL; Stack, Andrew G [ORNL; Bodnar, Robert J [ORNL

    2013-01-01

    Geologic storage of CO2 requires that the caprock sealing the storage rock is highly impermeable by CO2. Swelling clays, which are important components of caprocks, may react with CO2 under volume change, potentially impacting the seal quality. The interactions of scCO2 with Na saturated montmorillonite clay containing a sub-single layer of water in the interlayer region have been studied by sorption and neutron diffraction techniques. The excess sorption isotherms show maxima at bulk CO2 densities of 0.15 g/cm3, followed by an approximately linear decrease of excess sorption to zero and negative values with increasing CO2 bulk density. Neutron diffraction experiments on the same clay sample measured interlayer spacing and composition. The results show that limited amounts of CO2 are sorbed into the interlayer region, leading to depression of the interlayer peak intensity and an increase of the d(001) spacing by ca. 0.5 . The density of CO2 in the clay pores is relatively stable over a wide range of CO2 pressures at a given temperature, indicating the formation of a clay-CO2 phase. At low pressure increasing CO2 adsorption with decreasing temperature is observed while the high-pressure sorption properties exhibit weak or no temperature dependence. Supercritical fluids, sorption phenomena, carbon dioxide, carbon sequestration, caprock integrity

  6. CO2 Sorption to Subsingle Hydration Layer Montmorillonite Clay Studied by Excess Sorption and Neutron Diffraction Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Rother, Gernot; Ilton, Eugene S.; Wallacher, Dirk; Hauβ, Thomas; Schaef, Herbert T.; Qafoku, Odeta; Rosso, Kevin M.; Felmy, Andrew R.; Krukowski, Elizabeth G.; Stack, Andrew G.; Grimm, Nico; Bodnar, Robert J.

    2013-01-02

    Geologic storage of CO2 requires that the caprock sealing the storage rock is highly impermeable to CO2. Swelling clays, which are important components of caprocks, may interact with CO2 leading to volume change and potentially impacting the seal quality. The interactions of supercritical (sc) CO2 with Na saturated montmorillonite clay containing a subsingle layer of water in the interlayer region have been studied by sorption and neutron diffraction techniques. The excess sorption isotherms show maxima at bulk CO2 densities of ≈0.15 g/cm3, followed by an approximately linear decrease of excess sorption to zero and negative values with increasing CO2 bulk density. Neutron diffraction experiments on the same clay sample measured interlayer spacing and composition. The results show that limited amounts of CO2 are sorbed into the interlayer region, leading to depression of the interlayer peak intensity and an increase of the d(001) spacing by ca. 0.5 Å. The density of CO2 in the clay pores is relatively stable over a wide range of CO2 pressures at a given temperature, indicating the formation of a clay-CO2 phase. Finally, at the excess sorption maximum, increasing CO2 sorption with decreasing temperature is observed while the high-pressure sorption properties exhibit weak temperature dependence.

  7. Acute in vivo toxicity mitigation of PEI-coated maghemite nanoparticles using controlled oxidation and surface modifications toward siRNA delivery.

    Science.gov (United States)

    Israel, Liron Limor; Lellouche, Emmanuel; Ostrovsky, Stella; Yarmiayev, Valeria; Bechor, Moshe; Michaeli, Shulamit; Lellouche, Jean-Paul Moshe

    2015-07-22

    A ceric ammonium nitrate (CAN)-based doping step was used for the fabrication of core maghemite nanoparticles (NPs) that enabled the obtainment of colloid particles with a view to a high-level nanoparticle (NP) surface doping by Ce(III/IV). Such doping of Ce(III/IV) cations enables one to exploit their quite rich coordination chemistry for ligand coordinative binding. In fact, they were shown to act as powerful Lewis acid centers for attaching any organic (Lewis base) ligand such as a 25 kDa branched PEI polymer. Resulting conPEI25-CAN-γ-Fe2O3 NPs have been fully characterized before a successful implementation of siRNA loading and cell delivery/gene silencing using a well-known dual luciferase system. This attractive result emphasized their significant potential as an NP platform technology toward additional MRI and/or drug delivery (peptide)-relating end applications. However, due to their high positive charge, PEI polymers can cause severe in vivo toxicity due to their interaction with negatively charged red blood cells (RBC), resulting in RBC aggregation and lysis, leading to thrombosis and, finally, to animal death. In order to mitigate these acute toxic effects, two different types of surface modifications were performed. One modification included the controlled oxidation of 0.1-5% of the PEI amines before or after conjugation to the NPs, using hydrogen peroxide or potassium persulfate. The other type of modification was the addition of a second biocompatible polyanionic polymer to the PEI grafted NPs, based on the concept of a layer-by-layer (LbL) technique. This modification is based on the coordination of another polyanionic polymer on the NPs surface in order to create a combined hybrid PEI and polyanionic polymer nanosystem. In both cases, the surface modification successfully mitigated the NP acute in vivo toxicity, without compromising the silencing efficiency.

  8. Gas hydrates

    Digital Repository Service at National Institute of Oceanography (India)

    Ramprasad, T.

    and the role it plays in the global climate and the future of fuels. Russia, Japan, Nigeria, Peru, Chile, Pakistan, Indonesia, Korea, etc are various countries who are perusing the gas hydrates studies as a future resource for fuel. Indian Initiative..., 1993, Free gas at the base of the gas hydrate zone in the vicinity of the Chile Triple junction: Geology, v. 21, pp. 905-908. Borowski, W.S., C.K. Paull, and U. William, III, 1999, Global and local variations of interstitial sulfate gradients...

  9. Acetylcholinesterase immobilized onto PEI-coated silica nanoparticles.

    Science.gov (United States)

    Tumturk, Hayrettin; Yüksekdag, Hazer

    2016-01-01

    Polyethyleneimine (PEI) coated-silica nanoparticles were prepared by the Stöber method. The formation and the structure of the nanoparticles were characterized by ATR-FT-IR spectroscopy and transmission electron microscopy (TEM). TEM images of the silica and PEI-coated nanoparticles revealed that they were well dispersed and that there was no agglomeration. The acetylcholineesterase enzyme was immobilized onto these nanoparticles. The effects of pH and temperature on the storage stability of the free and immobilized enzyme were investigated. The optimum pHs for free and immobilized enzymes were determined as 7.0 and 8.0, respectively. The optimum temperatures for free and immobilized enzymes were found to be 30.0 and 35.0°C, respectively. The maximum reaction rate (Vmax) and the Michaelis-Menten constant (Km) were investigated for the free and immobilized enzyme. The storage stability of acetylcholinesterase was increased when immobilized onto the novel PEI-coated silica nanoparticles. The reuse numbers of immobilized enzyme were also studied. These hybrid nanoparticles are desirable as carriers for biomedical applications.

  10. Ultra-Small Graphene Oxide Functionalized with Polyethylenimine (PEI) for Very Efficient Gene Delivery in Cell and Zebrafish Embryos

    DEFF Research Database (Denmark)

    Zhou, Xiang; Laroche, Fabrice Jean Francois; Lamers, Gerda E M

    2012-01-01

    of DNA-condensing compounds required for efficient uptake of DNA. Here we report a polyethyleneimine (PEI) grafted ultra-small graphene oxide (PEI-g-USGO) for transfection. By removing the free PEI and ensuring a high PEI density on small sized graphene, we obtained very high transfection efficiencies...

  11. Role of Additives in Composite PEI/Oxide CO₂ Adsorbents: Enhancement in the Amine Efficiency of Supported PEI by PEG in CO₂ Capture from Simulated Ambient Air.

    Science.gov (United States)

    Sakwa-Novak, Miles A; Tan, Shuai; Jones, Christopher W

    2015-11-11

    Supported amines are promising candidate adsorbents for the removal of CO2 from flue gases and directly from ambient air. The incorporation of additives into polymeric amines such as poly(ethylenimine) (PEI) supported on mesoporous oxides is an effective strategy to improve the performance of the materials. Here, several practical aspects of this strategy are addressed with regards to direct air capture. The influence of three additives (CTAB, PEG200, PEG1000) was systematically explored under dry simulated air capture conditions (400 ppm of CO2, 30 °C). With SBA-15 as a model support for poly(ethylenimine) (PEI), the nature of the additive induced heterogeneities in the deposition of organic on the interior and exterior of the particles, an important consideration for future scale up to practical systems. The PEG200 additive increased the observed thermodynamic performance (∼60% increase in amine efficiency) of the adsorbents regardless of the PEI content, while the other molecules had less positive effects. A threshold PEG200/PEI value was identified at which the diffusional limitations of CO2 within the materials were nearly eliminated. The threshold PEG/PEI ratio may have physical origin in the interactions between PEI and PEG, as the optimal ratio corresponded to nearly equimolar OH/reactive (1°, 2°) amine ratios. The strategy is shown to be robust to the characteristics of the host support, as PEG200 improved the amine efficiency of PEI when supported on two varieties of mesoporous γ-alumina with PEI.

  12. F-127-PEI co-delivering docetaxel and TFPI-2 plasmid for nasopharyngeal cancer therapy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Tao, E-mail: taoliu18@126.com [Department of Otolaryngology, Zhujiang Hospital, Southern Medical University, Guangzhou 510282 (China); Zhang, Xinyu [Department of Otolaryngology, Zhujiang Hospital, Southern Medical University, Guangzhou 510282 (China); Ke, Bo [Jiangxi Key Laboratory of Hematological Oncology and Cell Biology, Jiangxi Provincial People' s Hospital, Nanchang 330006 (China); Wang, Yigang [School of Life Sciences, Zhejiang Sci-Tech University, Hangzhou 310018 (China); Wu, Xidong [Department of Pharmacology, Jiangxi Institute of Materia Medica,Nanchang 330029 (China); Jiang, Gang [Department of Otolaryngology, Zhujiang Hospital, Southern Medical University, Guangzhou 510282 (China); Wu, Ting [Department of Light Chemical Engineering, Guangdong Polytechnic, Foshan 528041 (China); Nie, Guohui, E-mail: nghui@21cn.com [Department of Otolaryngological, Peking University Shenzhen Hospital, Shenzhen 518036 (China)

    2016-04-01

    The co-delivery of drug and gene has become the primary strategy in cancer therapy. However, to construct one safe co-delivering system with higher drug loading and gene transfection efficiency for cancer therapy is still challenging. Herein, a novel degradable nanocarriers were synthesized and characterized in this study, which was composed of polyethylenimine (PEI)-linked PEO–PPO–PEO (Pluronic F127), called F127-PEI. Then the nanocarrier was used for hydrophobic docetaxel (DOC) and functional gene (TFPI-2 plasmid) co-delivery to treat nasopharyngeal cancer (NPC). The results indicated that F127-PEI nanocarriers had higher DOC loading amount and possessed good gene delivery effect in vitro. For co-delivery analysis, the obtained F127-PEI/DOC/TFPI-2 complexes could induce a more significant apoptosis than DOC or TFPI-2 alone, and decreased invasive capacity of NPC HNE-1 cells more obviously. Moreover, the F127-PEI copolymer exhibited better blood compatibility and lower cytotoxicity compared to PEI-25k by the hemolysis and MTT assays, which suggests a promising potential for NPC therapy. - Highlights: • F127-PEI was synthesized and used for drug and gene co-delivery. • F127-PEI showed good delivery ability to docetaxel and TFPI-2 plasmid. • The co-loaded complexes showed synergistic effect to nasopharyngeal carcinoma. • F127-PEI showed better blood safety and lower cytotoxicity compared to PEI-25k.

  13. Obsidian Hydration: A New Paleothermometer

    Energy Technology Data Exchange (ETDEWEB)

    Anovitz, Lawrence {Larry} M [ORNL; Riciputi, Lee R [ORNL; Cole, David R [ORNL; Fayek, Mostafa [ORNL; Elam, J. Michael [University of Tennessee, Knoxville (UTK)

    2006-01-01

    The natural hydration of obsidian was first proposed as a dating technique for young geological and archaeological specimens by Friedman and Smith (1960), who noted that the thickness of the hydrated layer on obsidian artifacts increases with time. This approach is, however, sensitive to temperature and humidity under earth-surface conditions. This has made obsidian hydration dating more difficult, but potentially provides a unique tool for paleoclimatic reconstructions. In this paper we present the first successful application of this approach, based on combining laboratory-based experimental calibrations with archaeological samples from the Chalco site in the Basin of Mexico, dated using stratigraphically correlated 14C results and measuring hydration depths by secondary ion mass spectrometry. The resultant data suggest, first, that this approach is viable, even given the existing uncertainties, and that a cooling trend occurred in the Basin of Mexico over the past 1450 yr, a result corroborated by other paleoclimatic data.

  14. Obsidian hydration: A new paleothermometer

    Science.gov (United States)

    Anovitz, Lawrence M.; Riciputi, Lee R.; Cole, David R.; Fayek, Mostafa; Elam, J. Michael

    2006-07-01

    The natural hydration of obsidian was first proposed as a dating technique for young geological and archaeological specimens by Friedman and Smith (1960), who noted that the thickness of the hydrated layer on obsidian artifacts increases with time. This approach is, however, sensitive to temperature and humidity under earth-surface conditions. This has made obsidian hydration dating more difficult, but potentially provides a unique tool for paleoclimatic reconstructions. In this paper we present the first successful application of this approach, based on combining laboratory-based experimental calibrations with archaeological samples from the Chalco site in the Basin of Mexico, dated using stratigraphically correlated 14C results and measuring hydration depths by secondary ion mass spectrometry. The resultant data suggest, first, that this approach is viable, even given the existing uncertainties, and that a cooling trend occurred in the Basin of Mexico over the past 1450 yr, a result corroborated by other paleoclimatic data.

  15. Polyethylenimine surface layer for enhanced virus immobilization on cellulose

    Science.gov (United States)

    Tiliket, Ghania; Ladam, Guy; Nguyen, Quang Trong; Lebrun, Laurent

    2016-05-01

    Thin regenerated cellulose films are prepared by hydrolysis of cellulose acetate (CA). A polycation, namely polyethylenimine (PEI), is then adsorbed onto the films. From QCM-D analysis, PEI readily adsorbs from a 0.1% w/v solution in NaCl 0.2 M (ca. 100 ng cm-2). Further PEI adsorption steps at higher PEI concentrations induce a linear growth of the PEI films, suggesting that free adsorption sites still exist after the initial adsorption. The adsorbed PEI chains are resistant to variations of the ionic strength up to NaCl 1 M. Promisingly, the adsorption of T4D bacteriophages are 15-fold more efficient onto the PEI-treated, compared to the native regenerated cellulose films, as measured by QCM-D. This confirms the strong affinity between the negatively charged viruses and PEI, even at low PEI concentration, probably governed by strong electrostatic attractive interactions. This result explains the remarkable improvement of the affinity of medical masks for virus droplets when one of their cellulose layers was changed by two-PEI-functionalized cellulose-based filters.

  16. Synthesis of Pt/PEI-MWCNT composite materials on polyethyleneimine-functionalized MWNTs as supports

    Energy Technology Data Exchange (ETDEWEB)

    Yi, Sung-Chul; Jung, Chi Young [Department of Chemical Engineering, Hanyang University, Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Kim, Wha Jung, E-mail: whajungk@konkuk.ac.kr [Department of Materials Chemistry and Engineering, Konkuk University, 1-Hwayang-dong, Kwangjin-gu, Seoul 143-701 (Korea, Republic of)

    2011-12-15

    Graphical abstract: Schematic diagram for (a) the preparation of Pt/MWCNT functionalized with PEI and (b) TEM of Pt/PEI-MWCNT. Highlights: Black-Right-Pointing-Pointer We prepared Pt/PEI/MWCNT where MWCNT was first functionalized by PEI (polyethyleneimine) followed by Pt deposit onto it. Black-Right-Pointing-Pointer PEI functionalization provided high density homogeneous functional groups on MWCNT's sidewall. Black-Right-Pointing-Pointer Cationic PEI leads to homogeneous dispersion in solutions such as water and organic solvents. Black-Right-Pointing-Pointer Pt/PEI/MWCNT catalyst exhibits excellent electrocatalytic activity compared to that of Pt/MWCNT catalyst obtained with polyvinylpyrrolidine (PVP). -- Abstract: Composite materials with highly dispersed platinum (Pt) nanoparticles on multiwalled carbon nanotubes (MWCNTs), functionalized with polyethyleneimine (PEI) by a noncovalent method were prepared. The PEI-functionalization provided high density homogeneous functional groups on the MWCNTs' sidewalls for binding Pt nanoparticles. Cationic PEI leads to homogeneous dispersion in solutions such as water and organic solvents. The effects of a reducing agent on the Pt nanoparticles that form on the surfaces of the MWCNT were studied by varying the molar ratio of NaOH to H{sub 2}PtCl{sub 6}. These composite materials were characterized with transmission electron micrograph (TEM), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS). The Pt/PEI-MWCNT catalyst exhibits excellent electrocatalytic activity and compared with Pt/PVP-MWCNT catalysts obtained with polyvinylpyrrolidone (PVP). Finally, the cyclic voltammogram of methanol electrooxidation for Pt/PEI-MWCNT shows better tolerance to CO and methanol oxidation to CO{sub 2} than of Pt/PVP-MWCNT.

  17. Chondrocyte Behavior on Micropatterns Fabricated Using Layer-by-Layer Lift-Off: Morphological Analysis

    Directory of Open Access Journals (Sweden)

    Jameel Shaik

    2013-01-01

    Full Text Available Cell patterning has emerged as an elegant tool in developing cellular arrays, bioreactors, biosensors, and lab-on-chip devices and for use in engineering neotissue for repair or regeneration. In this study, micropatterned surfaces were created using the layer-by-layer lift-off (LbL-LO method for analyzing canine chondrocytes response to patterned substrates. Five materials were chosen based on our previous studies. These included: poly(dimethyldiallylammonium chloride (PDDA, poly(ethyleneimine (PEI, poly(styrene sulfonate (PSS, collagen, and chondroitin sulfate (CS. The substrates were patterned with these five different materials, in five and ten bilayers, resulting in the following multilayer nanofilm architectures: (PSS/PDDA5, (PSS/PDDA10; (CS/PEI4/CS, (CS/PEI9/CS; (PSS/PEI5, (PSS/PEI10; (PSS/Collagen5, (PSS/Collagen10; (PSS/PEI4/PSS, (PSS/PEI9/PSS. Cell characterization studies were used to assess the viability, longevity, and cellular response to the configured patterned multilayer architectures. The cumulative cell characterization data suggests that cell viability, longevity, and functionality were enhanced on micropatterned PEI, PSS, collagen, and CS multilayer nanofilms suggesting their possible use in biomedical applications.

  18. Linear and Branched PEIs (Polyethylenimines and Their Property Space

    Directory of Open Access Journals (Sweden)

    Claudiu N. Lungu

    2016-04-01

    Full Text Available A chemical property space defines the adaptability of a molecule to changing conditions and its interaction with other molecular systems determining a pharmacological response. Within a congeneric molecular series (compounds with the same derivatization algorithm and thus the same brute formula the chemical properties vary in a monotonic manner, i.e., congeneric compounds share the same chemical property space. The chemical property space is a key component in molecular design, where some building blocks are functionalized, i.e., derivatized, and eventually self-assembled in more complex systems, such as enzyme-ligand systems, of which (physico-chemical properties/bioactivity may be predicted by QSPR/QSAR (quantitative structure-property/activity relationship studies. The system structure is determined by the binding type (temporal/permanent; electrostatic/covalent and is reflected in its local electronic (and/or magnetic properties. Such nano-systems play the role of molecular devices, important in nano-medicine. In the present article, the behavior of polyethylenimine (PEI macromolecules (linear LPEI and branched BPEI, respectively with respect to the glucose oxidase enzyme GOx is described in terms of their (interacting energy, geometry and topology, in an attempt to find the best shape and size of PEIs to be useful for a chosen (nanochemistry purpose.

  19. Linear and Branched PEIs (Polyethylenimines) and Their Property Space

    Science.gov (United States)

    Lungu, Claudiu N.; Diudea, Mircea V.; Putz, Mihai V.; Grudziński, Ireneusz P.

    2016-01-01

    A chemical property space defines the adaptability of a molecule to changing conditions and its interaction with other molecular systems determining a pharmacological response. Within a congeneric molecular series (compounds with the same derivatization algorithm and thus the same brute formula) the chemical properties vary in a monotonic manner, i.e., congeneric compounds share the same chemical property space. The chemical property space is a key component in molecular design, where some building blocks are functionalized, i.e., derivatized, and eventually self-assembled in more complex systems, such as enzyme-ligand systems, of which (physico-chemical) properties/bioactivity may be predicted by QSPR/QSAR (quantitative structure-property/activity relationship) studies. The system structure is determined by the binding type (temporal/permanent; electrostatic/covalent) and is reflected in its local electronic (and/or magnetic) properties. Such nano-systems play the role of molecular devices, important in nano-medicine. In the present article, the behavior of polyethylenimine (PEI) macromolecules (linear LPEI and branched BPEI, respectively) with respect to the glucose oxidase enzyme GOx is described in terms of their (interacting) energy, geometry and topology, in an attempt to find the best shape and size of PEIs to be useful for a chosen (nanochemistry) purpose. PMID:27089324

  20. Linear and Branched PEIs (Polyethylenimines) and Their Property Space.

    Science.gov (United States)

    Lungu, Claudiu N; Diudea, Mircea V; Putz, Mihai V; Grudziński, Ireneusz P

    2016-04-13

    A chemical property space defines the adaptability of a molecule to changing conditions and its interaction with other molecular systems determining a pharmacological response. Within a congeneric molecular series (compounds with the same derivatization algorithm and thus the same brute formula) the chemical properties vary in a monotonic manner, i.e., congeneric compounds share the same chemical property space. The chemical property space is a key component in molecular design, where some building blocks are functionalized, i.e., derivatized, and eventually self-assembled in more complex systems, such as enzyme-ligand systems, of which (physico-chemical) properties/bioactivity may be predicted by QSPR/QSAR (quantitative structure-property/activity relationship) studies. The system structure is determined by the binding type (temporal/permanent; electrostatic/covalent) and is reflected in its local electronic (and/or magnetic) properties. Such nano-systems play the role of molecular devices, important in nano-medicine. In the present article, the behavior of polyethylenimine (PEI) macromolecules (linear LPEI and branched BPEI, respectively) with respect to the glucose oxidase enzyme GOx is described in terms of their (interacting) energy, geometry and topology, in an attempt to find the best shape and size of PEIs to be useful for a chosen (nanochemistry) purpose.

  1. Synthesis of Superparamagnetic Iron Oxide Nanoparticles Modified with MPEG-PEI via Photochemistry as New MRI Contrast Agent

    Directory of Open Access Journals (Sweden)

    Yancong Zhang

    2015-01-01

    Full Text Available Novel method for synthesis of superparamagnetic iron oxide nanoparticles (SPIONs coated with polyethylenimine (PEI and modified with poly(ethylene glycol methyl ether (MPEG, MPEG-PEI-SPIONs, was developed. PEI-SPIONs were successfully prepared in aqueous system via photochemistry, and their surface was modified with poly(ethylene glycol methyl ether (MPEG. The so-obtained MPEG-PEI-SPIONs had a uniform hydrodynamic particle size of 34 nm. The successful coating of MPEG-PEI on the SPIONs was ascertained from FT-IR analysis, and the PEI and MPEG fractions in MPEG-PEI-SPIONs were calculated to account for 31% and 12%, respectively. Magnetic measurement revealed that the saturated magnetization of MPEG-PEI-SPIONs reached 46 emu/g and the nanoparticles showed the characteristic of being superparamagnetic. The stability experiment revealed that the MPEG-PEI modification improved the nanoparticles stability greatly. T2 relaxation measurements showed that MPEG-PEI-SPIONs show similar R2 value to the PEI-SPIONs. The T2-weighted magnetic resonance imaging (MRI of MPEG-PEI-SPIONs showed that the magnetic resonance signal was enhanced significantly with increasing nanoparticle concentration in water. These results indicated that the MPEG-PEI-SPIONs had great potential for application in MRI.

  2. 正电型PVC/PEI复合纳滤膜的制备及其盐/染料分离性能∗%Fabrication anddye-salt separation of positively charged PVC/PEI composite nanofiltration membranes

    Institute of Scientific and Technical Information of China (English)

    崔月; 许云秋; 姚之侃; 杜世媛; 赵斌; 朱宝库; 朱利平

    2014-01-01

    在聚氯乙烯(PVC)超滤膜表面通过沉积形成与之共价结合的聚乙烯亚胺(PEI)层,先后用戊二醛和2,3-环氧丙基三甲基氯化铵(EPTAC)令 PEI 交联和季铵化,制备了荷正电 PVC/PEI 复合纳滤膜;考察PEI分子量和 EPTAC 浓度对膜结构及性能的影响.结果表明,当分子量分别为5万和7万的两种 PEI 按质量比1∶1混合使用时,可以得到皮层致密均一的复合膜,EPTAC 季铵化后 PVC/PEI 复合纳滤膜荷正电,有良好的亲水性,0.3 MP a 操作压力下水通量达58.7 L/m2·h,对 NaCl 不截留,对刚果红染料的截留率达98.9%,在染料和无机盐分离领域具有重要意义.%By filtering deposition of polyethylene imine (PEI)and then crosslinking by glutaraldehyde,a dense separation layer was introduced onto the surface of PVC ultrafiltration membrane.On this basis,positively charged PVC/PEI composite NF membrane was prepared after the reaction between the remaining amino groups and 2,3-epoxy-trimethyl ammonium chloride(EPTAC).It was found that we would achieve PVC nanofiltration membrane with the best performance using mixture of PEI-7w and PEI-2w (1∶1 ).The PVC/PEI composite NF membrane showed good hydrophilicity and great nanofiltration performance.Under the operating pressure of 0.3 MPa,the Congo red rejection and flux is 98.9% and 58.7 L/m2 ·h,respectively,while the NaCl rejection is almost zero.Thus,the PVC nanofiltration membrane was quite qualified for the separation of mixed inorgan-icsalt and dye solution.This approach is a promising way for fabricating PVC NF membrane with high water flux and dye rej ection.

  3. Solid state tungsten oxide hydrate/tin oxide hydrate electrochromic device prepared by electrochemical reactions

    Science.gov (United States)

    Nishiyama, Kentaro; Matsuo, Ryo; Sasano, Junji; Yokoyama, Seiji; Izaki, Masanobu

    2017-03-01

    The solid state electrochromic device composed of tungsten oxide hydrate (WO3(H2O)0.33) and tin oxide hydrate (Sn(O,OH)) has been constructed by anodic deposition of WO3(H2O)0.33 and Sn(O,OH) layers and showed the color change from clear to blue by applying voltage through an Au electrode.

  4. Inverted bulk-heterojunction solar cell with cross-linked hole-blocking layer

    Science.gov (United States)

    Udum, Yasemin; Denk, Patrick; Adam, Getachew; Apaydin, Dogukan H.; Nevosad, Andreas; Teichert, Christian; S. White, Matthew.; S. Sariciftci, Niyazi.; Scharber, Markus C.

    2014-01-01

    We have developed a hole-blocking layer for bulk-heterojunction solar cells based on cross-linked polyethylenimine (PEI). We tested five different ether-based cross-linkers and found that all of them give comparable solar cell efficiencies. The initial idea that a cross-linked layer is more solvent resistant compared to a pristine PEI layer could not be confirmed. With and without cross-linking, the PEI layer sticks very well to the surface of the indium–tin–oxide electrode and cannot be removed by solvents used to process PEI or common organic semiconductors. The cross-linked PEI hole-blocking layer functions for multiple donor–acceptor blends. We found that using cross-linkers improves the reproducibility of the device fabrication process. PMID:24817837

  5. Clathrate hydrates in nature.

    Science.gov (United States)

    Hester, Keith C; Brewer, Peter G

    2009-01-01

    Scientific knowledge of natural clathrate hydrates has grown enormously over the past decade, with spectacular new findings of large exposures of complex hydrates on the sea floor, the development of new tools for examining the solid phase in situ, significant progress in modeling natural hydrate systems, and the discovery of exotic hydrates associated with sea floor venting of liquid CO2. Major unresolved questions remain about the role of hydrates in response to climate change today, and correlations between the hydrate reservoir of Earth and the stable isotopic evidence of massive hydrate dissociation in the geologic past. The examination of hydrates as a possible energy resource is proceeding apace for the subpermafrost accumulations in the Arctic, but serious questions remain about the viability of marine hydrates as an economic resource. New and energetic explorations by nations such as India and China are quickly uncovering large hydrate findings on their continental shelves.

  6. Obsidian hydration profiles measured by sputter-induced optical emission.

    Science.gov (United States)

    Tsong, I S; Houser, C A; Yusef, N A; Messier, R F; White, W B; Michels, J W

    1978-07-28

    The variation of concentrations of hydrogen, sodium, potassium, lithium, calcium, magnesium, silicon, and aluminum as a function of depth in the hydration layer of obsidian artifacts has been determined by sputter-induced optical emission. The surface hydration is accompanied by dealkalization, and there is a buildup of alkaline earths, calcium and magnesium in the outermost layers. These results have clarified the phenomena underlying the obsidian hydration dating technique.

  7. Dexamethasone-loaded reconstitutable charged polymeric (PLGA)n -b-bPEI micelles for enhanced nuclear delivery of gene therapeutics.

    Science.gov (United States)

    Mishra, Deepa; Kang, Han Chang; Cho, Hana; Bae, You Han

    2014-06-01

    This study investigates the potential of dexamethasone (Dex) to enhance the nuclear accumulation and subsequent gene expression of plasmid DNA (pDNA) delivered using a charged polymeric micelle-based gene delivery system. (PLGA)n -b-bPEI25kDa block copolymers are synthesized and used to prepare Dex-loaded cationic micelles (DexCM). After preparing DexCM/pDNA complexes, bPEI1.8kDa is coated on the complexes using a Layer-by-Layer (LbL) technique to construct DexCM/pDNA/bPEI1.8kDa complexes (i.e., LbL-DexCM polyplexes) that are 100-180 nm in diameter and have a zeta potential of 30-40 mV. In MCF7 cells, LbL-DexCM polyplexes cause 3-13-fold higher transfection efficiencies compared to LbL-CM polyplexes and show negligible cytotoxicity. LbL-DexCM3 polyplexes induce much higher nuclear delivery of pDNA compared to LbL-CM3 polyplexes. These results suggest that Dex-loaded polyplexes could be used in gene and drug delivery applications to increase nuclear accumulation of therapeutic payloads, further leading to a decrease in the dose of the drug and gene necessary to achieve equivalent therapeutic effects.

  8. Hydration states of AFm cement phases

    Energy Technology Data Exchange (ETDEWEB)

    Baquerizo, Luis G., E-mail: luis.baquerizoibarra@holcim.com [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Matschei, Thomas [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Scrivener, Karen L. [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Saeidpour, Mahsa; Wadsö, Lars [Building Materials, Lund University, Box 124, 221 000 Lund (Sweden)

    2015-07-15

    The AFm phase, one of the main products formed during the hydration of Portland and calcium aluminate cement based systems, belongs to the layered double hydrate (LDH) family having positively charged layers and water plus charge-balancing anions in the interlayer. It is known that these phases present different hydration states (i.e. varying water content) depending on the relative humidity (RH), temperature and anion type, which might be linked to volume changes (swelling and shrinkage). Unfortunately the stability conditions of these phases are insufficiently reported. This paper presents novel experimental results on the different hydration states of the most important AFm phases: monocarboaluminate, hemicarboaluminate, strätlingite, hydroxy-AFm and monosulfoaluminate, and the thermodynamic properties associated with changes in their water content during absorption/desorption. This data opens the possibility to model the response of cementitious systems during drying and wetting and to engineer systems more resistant to harsh external conditions.

  9. Solution Behavior of Modified Polyethylenimine (PEI) Polymers by Light Scattering Investigations

    Energy Technology Data Exchange (ETDEWEB)

    Sonny A. Ekhorutomwen; Samuel P. Sawan; Barbara F. Smith; Thomas W. Robison; Kennard V. Wilson

    2004-03-18

    The eight average molecular weights, as well as other characteristics such as the second virial coefficients and root-mean-square (RMS) radii of gyration of poly (ethyleneimine) (PEI) and various derivatives, have been determined in solution light scattering studies. The solution dynamics of PEI and carboxylated and phosphorylated derivatives were studied a pH of 3.3, 7.0 and 10.0. Measurements were made in freshly distilled and de-ionized water as well as in 0.1 M, 1 M and 5-M solutions of sodium chloride in water. Molecular weights were calculated from Berry plots. The purified polymer, PEI-1, gave a molecular weight of 39,600 g/mol., while the same polymer, which was not purified, PEI-2, has MW of 43,100 g/mol.

  10. BMP2 gene delivery to bone mesenchymal stem cell by chitosan-g-PEI nonviral vector

    Science.gov (United States)

    Yue, Jianhui; Wu, Jun; Liu, Di; Zhao, Xiaoli; Lu, William W.

    2015-04-01

    Nanotechnology has made a significant impact on the development of nanomedicine. Nonviral vectors have been attracting more attention for the advantage of biosafety in gene delivery. Polyethylenimine (PEI)-conjugated chitosan (chitosan-g-PEI) emerged as a promising nonviral vector and has been demonstrated in many tumor cells. However, there is a lack of study focused on the behavior of this vector in stem cells which hold great potential in regenerative medicine. Therefore, in this study, in vitro gene delivering effect of chitosan-g-PEI was investigated in bone marrow stem cells. pIRES2-ZsGreen1-hBMP2 dual expression plasmid containing both the ZsGreen1 GFP reporter gene and the BMP2 functional gene was constructed for monitoring the transgene expression level. Chitosan-g-PEI-mediated gene transfer showed 17.2% of transfection efficiency and more than 80% of cell viability in stem cells. These values were higher than that of PEI. The expression of the delivered BMP2 gene in stem cells enhanced the osteogenic differentiation. These results demonstrated that chitosan-g-PEI is capable of applying in delivering gene to stem cells and providing potential applications in stem cell-based gene therapy.

  11. Gas hydrate dissociation structures in submarine slopes

    Energy Technology Data Exchange (ETDEWEB)

    Gidley, I.; Grozic, J.L.H. [Calgary Univ., AB (Canada). Dept. of Civil Engineering

    2008-07-01

    Studies have suggested that gas hydrates may play a role in submarine slope failures. However, the mechanics surrounding such failures are poorly understood. This paper discussed experimental tests conducted on a small-scale physical model of submarine soils with hydrate inclusions. The laboratory tests investigated the effects of slope angle and depth of burial of the hydrate on gas escape structures and slope stability. Laponite was used to model the soils due to its ability to swell and produce a clear, colorless thixotropic gel when dispersed in water. An R-11 refrigerant was used to form hydrate layers and nodules. The aim of the experiment was to investigate the path of the fluid escape structures and the development of a subsequent slip plane caused by the dissociation of the R-11 hydrates. Slope angles of 5, 10, and 15 degrees were examined. Slopes were examined using high-resolution, high-speed imaging techniques. Hydrate placement and slope inclinations were varied in order to obtain stability data. Results of the study showed that slope angle influenced the direction of travel of the escaping gas, and that the depth of burial affected sensitivity to slope angle. Theoretical models developed from the experimental data have accurately mapped deformations and stress states during testing. Further research is being conducted to investigate the influence of the size, shape, and placement of the hydrates. 30 refs., 15 figs.

  12. Suspeita de febre familiar dos cães Shar-peis chineses Suspected familiar chinese Shar-pei dog fever

    Directory of Open Access Journals (Sweden)

    Marcia Regina da Silva Ilha

    2005-06-01

    Full Text Available A febre (síndrome familiar dos cães Shar-peis Chineses é uma doença hereditária autossômica recessiva. Este trabalho descreve um caso de amiloidose generalizada em um cão Shar-pei Chinês, fêmea, de três anos de idade, cujo quadro clínico-patológico é consistente com o da febre familiar dos cães Shar-peis chineses. Esse animal tinha uma história clínica de edema bilateral recidivante na região do jarrete que vinha sendo observado desde os sete meses de idade. Três dias antes da morte, esse cão apresentou anorexia, apatia, vômito e diarréia. À necropsia, ambos os rins estavam firmes, pálidos e possuíam a superfície capsular irregular. Histologicamente foram observados depósitos de amilóide nos rins, no pâncreas, na tireóide e no baço. Esse amilóide perdeu sua afinidade para o vermelho Congo, quando utilizado o permanganato de potássio. Esse achado é consistente com amiloidose do tipo AA.Chinese Shar-pei familial fever is a breed-associated hereditary autosomal recessive disease of Chinese Shar-pei dogs. A case of generalized amyloidosis in a 3-year-old female Chinese Shar-pei dog with a tentative diagnosis of familial Chinese Shar-pei fever is described. This animal had a clinical history of episodic bilateral swelling of the tarsal joints since 7-month-old. Vomiting, diarrhea, anorexia and lethargy were observed 3 days prior to death. At necropsy, both kidneys were firm, whitish and had an irregular capsular surface. Microscopically, amyloid deposits were observed in the kidneys, pancreas, thyroid glands and spleen. Amyloid deposits lost their affinity for Congo red after treatment with potassium permanganate indicating AA-type amyloidosis.

  13. Positively charged and bipolar layered poly(ether imide) nanofiltration membranes for water softening applications

    Science.gov (United States)

    Gassara, S.; Abdelkafi, A.; Quémener, D.; Amar, R. Ben; Deratani, A.

    2015-07-01

    Poly(ether imide) (PEI) ultrafiltration membranes were chemically modified with branched poly(ethyleneimine) to obtain nanofiltration (NF) membrane Cat PEI with a positive charge in the pH range below 9. An oppositely charged polyelectrolyte layer was deposited on the resulting membrane surface by using sodium polystyrene sulfonate (PSSNa) and sodium polyvinyl sulfonate (PVSNa) to prepare a bipolar layered membrane NF Cat PEI_PSS and Cat PEI_PVS having a negatively charged surface and positively charged pores. Cat PEI exhibited good performance to remove multivalent cations (more than 90% of Ca2+) from single salt solutions except in presence of sulfate ions. Adding an anionic polyelectrolyte layer onto the positively charged surface resulted in a significant enhancement of rejection performance even in presence of sulfate anions. Application of the prepared membranes in water softening of natural complex mixtures was successful for the different studied membranes and a large decrease of hardness was obtained. Moreover, Cat PEI_PSS showed a good selectivity for nitrate removal. Fouling experiments were carried out with bovine serum albumin, as model protein foulant. Cat PEI_PSS showed much better fouling resistance than Cat PEI with a quantitative flux recovery ratio.

  14. Prediction of gas hydrate saturation throughout the seismic section in Krishna Godavari basin using multivariate linear regression and multi-layer feed forward neural network approach

    Digital Repository Service at National Institute of Oceanography (India)

    Singh, Y.; Nair, R.R.; Singh, H.; Datta, P.; Jaiswal, P.; Dewangan, P.; Ramprasad, T.

    -Godavari basin. Log prediction process, with uncertainties based on root mean square error properties, was implemented by way of a multi-layer feed forward neural network. The log properties were merged with seismic data by applying a non-linear transform...

  15. [Aspirin-PEI-beta-CyD as a novel non-viral vector for gene transfer].

    Science.gov (United States)

    Wang, Zhong-Ren; Chen, Dan; Zhou, Jun; Tang, Gu-Ping

    2009-01-01

    To develop a novel non-viral gene delivery vector based on PEI-beta-CyD as backbone modified with aspirin, and to identify its physicochemical characters. 1, 1-carbonyldiimidazole (CDI) was used to bind aspirin onto PEI-beta-CyD to form PEI-beta-CyD-ASP. (1)H-NMR, FT-IR, UV and XRD were used to confirm the polymer structure. The ability of condensation was demonstrated by gel retardation assay. MTT assay was used to test the cell viability in B16, Hela and A293 cell lines. Transfection efficiency of the polymer was tested in B16 cells. The structure of PEI-beta-CyD-ASP was confirmed by (1)H-NMR, FT-IR, UV and XRD, which efficiently condensed plasmid DNA at the N/P ratio of 4. The copolymer showed low cytotoxicity and high transfection efficiency in B16 cells. The synthesized aspirin-PEI-beta-CyD might be a potential gene delivery vector.

  16. Bioreducible crosslinked low molecular weight branched PEI-PBLG as an efficient gene carrier

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Low molecular weight polyethylenimine-poly(gamma-benzyl L-glutamate) (PEI-PBLG) was crosslinked by N,N’-cystaminebisacrylamide (CBA) to get the polymer named as CBA-PEI-PBLG (CPP).CPP not only inherits PEI-PBLG’s amphiphilic advantages,but also possesses reducible properties.CPP can complex with DNA to form nanoparticles.CPP/DNA complex particles were characterized by particle size and zeta potential analysis.The result showed that the complex particles have suitable size and surface charges for gene delivery.And gel retardation assay also prove CBA-PEI-PBLG has proper condensing ability for DNA.CPP has good reducible property,and also has good biocompatibility because of introducing PBLG segment.The cytotoxicity of CPP was evaluated using MTT assay,and the results showed CPP has lower cytotoxicity compared with PEI 25 K.The transfection properties were characterized in different cells by using plasmid DNA as a reporter.CPP showed higher transfection efficiencies and lower cytotoxicity in HeLa cells.This was attributed to bioreducible and biocompatibility properties of the CPP.These results suggested that CPP is a promising low-toxic,highly effective non-viral gene carrier.

  17. Preparation of PVA/PEI ultra-fine fibers and their composite membrane with PLA by electrospinning.

    Science.gov (United States)

    Dong, Cunhai; Yuan, Xiaoyan; He, Mingyu; Yao, Kangde

    2006-01-01

    Ultra-fine fibers of poly(vinyl alcohol)/polyethylenimine (PVA/PEI) were prepared by electrospinning of their blend solutions in water. Effects of PVA/PEI mass ratio and the polymer concentration on the fiber morphology were discussed by analysis of scanning electron micrographs. Results showed that uniform ultra-fine fibers could be obtained from an 8% PVA/PEI solution with 75:25 mass ratio. It was supposed that the introduction of PVA could promote electrospinning of PEI by weakening the intermolecular interaction and increasing solution viscosity. A composite membrane of PVA/PEI with poly(D,L-lactide) (PLA) was produced by co-electrospinning simultaneously from the aqueous 8% PVA/PEI (75:25) solution and a 20% PLA solution in N,N-dimethylformamide in two separated syringes. Fourier transform infrared spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy verified the existence of PVA/PEI and PLA in the fibrous membrane. We attempted to incorporate PEI with PLA as ultra-fine fibers to diminish the acidic inflammation caused by biodegradation of PLA. The fibrous composite membrane of PVA/PEI-PLA could provide better biocompatibility and would be used as drug-delivery carriers or tissue-engineering scaffolds.

  18. Dielectric dispersion and protonic conduction in hydrated purple membrane.

    Science.gov (United States)

    Kovács, I; Váró, G

    1988-01-01

    Dielectric dispersion effects were studied in purple membranes of different hydration levels. The capacitance and conductivity were measured over the frequency range of 10(2) Hz to 10(5) Hz. With increase in the hydration level, the conductivity increases sharply above the critical hydration of hc = 0.06 g H2O/g protein. This critical hydration is close to the extent of the first continuous strongly bound water layer and is interpreted as the threshold for percolative proton transfer. The capacitance increases continuously with increasing hydration and a larger increase above the water content of 0.1 g H2O/g protein can be seen only at low frequencies. Maxwell-Wagner relaxation also appears above this hydration, showing the presence of a bulk water phase.

  19. Cellular delivery of shRNA using aptamer-conjugated PLL-alkyl-PEI nanoparticles.

    Science.gov (United States)

    Askarian, Saeedeh; Abnous, Khalil; Taghavi, Sahar; Oskuee, Reza Kazemi; Ramezani, Mohammad

    2015-12-01

    Introduction of an efficient gene delivery vector is still the main challenge of gene therapy. Both polyethylenimine (PEI) and poly(l-lysine) (PLL) comprise disadvantages which limited their application. To explore whether their deficiencies could be compensated by preparing copolymers consisting of both PLL and PEI, we generated several combinations of PLL-alkyl-PEI copolymers conjugated to aptamer and evaluated their both gene delivery efficiency and down-regulation of Bcl-XL, an anti-apoptotic gene, in lung cancer cell line. PLL was conjugated to either 10% or 50% of PEI by grafting different percentages of PEI to alkylated-PLL as core. The properties of modified polymers including size, surface charge density, DNA condensation ability, buffering capacity and cytotoxicity were evaluated. According to transfection results, aptamer conjugated PLL-alkyl-10%-PEI (PLPE8%) was selected for further gene silencing study by plasmid shRNA. Decrease in Bcl-XL gene expression was estimated by both RT-PCR and western-blot experiments. The obtained results revealed that the new copolymers had appropriate nano-scale size (117-128 nm) even after aptamer conjugation (168-183 nm). Moreover, they exhibited increased transfection efficiencies by up to 1.8-5 folds and acceptable cytotoxicity. The apoptosis was induced in transfected cells by shRNA-aptamer-copolymer due to the down-regulation of mRNA and protein levels. This study suggested a new vector for targeted non-viral gene delivery with high transfection efficiency in lung cancer or pulmonary systems. Copyright © 2015 Elsevier B.V. All rights reserved.

  20. Facile fabrication of AgNPs/(PVA/PEI) nanofibers: high electrochemical efficiency and durability for biosensors.

    Science.gov (United States)

    Zhu, Han; Du, MingLiang; Zhang, Ming; Wang, Pan; Bao, ShiYong; Wang, LiNa; Fu, YaQin; Yao, JuMing

    2013-11-15

    A novel, facile and green approach for the fabrication of H2O2, glutathione (GSH) and glucose detection biosensor using water-stable PVA and PVA/PEI nanofibers decorated with AgNPs by combining an in situ reduction approach and electrospinning technique has been demonstrated. Small, uniform and well-dispersed AgNPs embedded in the PVA nanofibers and immobilized on functionalized PVA/PEI nanofibers indicate the highly sensitive detection of H2O2 with a detection limit of 5 μM and exhibit a fast response, broad linear range, low detection limit and excellent stability and reusability.

  1. Exploitation of subsea gas hydrate reservoirs

    Science.gov (United States)

    Janicki, Georg; Schlüter, Stefan; Hennig, Torsten; Deerberg, Görge

    2016-04-01

    Natural gas hydrates are considered to be a potential energy resource in the future. They occur in permafrost areas as well as in subsea sediments and are stable at high pressure and low temperature conditions. According to estimations the amount of carbon bonded in natural gas hydrates worldwide is two times larger than in all known conventional fossil fuels. Besides technical challenges that have to be overcome climate and safety issues have to be considered before a commercial exploitation of such unconventional reservoirs. The potential of producing natural gas from subsea gas hydrate deposits by various means (e.g. depressurization and/or injection of carbon dioxide) is numerically studied in the frame of the German research project »SUGAR«. The basic mechanisms of gas hydrate formation/dissociation and heat and mass transport in porous media are considered and implemented into a numerical model. The physics of the process leads to strong non-linear couplings between hydraulic fluid flow, hydrate dissociation and formation, hydraulic properties of the sediment, partial pressures and seawater solution of components and the thermal budget of the system described by the heat equation. This paper is intended to provide an overview of the recent development regarding the production of natural gas from subsea gas hydrate reservoirs. It aims at giving a broad insight into natural gas hydrates and covering relevant aspects of the exploitation process. It is focused on the thermodynamic principles and technological approaches for the exploitation. The effects occurring during natural gas production within hydrate filled sediment layers are identified and discussed by means of numerical simulation results. The behaviour of relevant process parameters such as pressure, temperature and phase saturations is described and compared for different strategies. The simulations are complemented by calculations for different safety relevant problems.

  2. Hydration Assessment of Athletes

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ KEY POINTS · Although there is no scientific consensus for 1 ) howbest to assess the hydration status of athletes, 2)what criteria to use as acceptable outcome measurements, or 3) the best time to apply practical assessment methods, there are methods that can be used toprovide athletes with useful feedback about their hydration status

  3. Preparation Gold-PEI Nanoparticles for Gene Delivery%纳米金-聚乙烯亚胺基因载体的制备

    Institute of Scientific and Technical Information of China (English)

    卢耀勇; 王冬晓; 王建国; 张霞; 王莺

    2013-01-01

    layer-by-layer method to prepare gold-PEI gene carrier.Gold nanoparticles were prepared by citrate reduction and then 11-mercaptoundecanoie acid (MUA) was to be deposited on the gold surface to facilitate the binding of the subsequent layers followed by the addition of PEI to prepare Gold-PEI nanoparticles.The naoparticles in each procedure was characterized by dynamic lighting scatter (DLS),UV-vis spectra and transmission electron microscopy (TEM),respectively.Results:We successfully fabricated Gold-PEI nanoparticles for gene carrier.It was shown that the product size in each procedure was about 20-30 nm and their polydispersity (PDI) was below 0.2,indicating the solution of products was distributed uniformly.Additionally,a change of the zeta-potential after completion of each layer signified the deposition of each reactant.As a whole,the size of gold-PEI had no obvious increase compared with that of gold nanoparticles.Our results suggested that the morphologies of gold,gold-MUA and gold-PEI nanoparticles were approximately spherical shape as measured by TEM.Conclusion:We manufactured gold-PEI nanopartieles for gene delivery by layer-by-layer approach.The gold-PEI nanoparticles was expected to be a promising gene carrier allowing for increasing its silence effect in targeted cells and improving gene-regulated efficiency.

  4. The Possible "Proton Sponge " Effect of Polyethylenimine (PEI) Does Not Include Change in Lysosomal pH

    DEFF Research Database (Denmark)

    Søndergaard, Rikke Vicki; Mattebjerg, Maria Ahlm; Henriksen, Jonas Rosager

    2013-01-01

    " hypothesis. Our measurements show that PEI does not induce change in lysosomal pH as previously suggested and quantification of PEI concentrations in lysosomes makes it uncertain that the "proton sponge " effect is the dominant mechanism of polyplex escape.Molecular Therapy (2012); doi:10.1038/mt.2012.185....

  5. PEG-PEI/siROCK2 Protects Against Aβ42-Induced Neurotoxicity in Primary Neuron Cells for Alzheimer Disease.

    Science.gov (United States)

    Liu, Yunyun; Yang, Xingyi; Lei, Qingfeng; Li, Zhong; Hu, Jingyang; Wen, Xiaojun; Wang, Huijun; Liu, Zhonglin

    2015-08-01

    Gene therapy that targets the ROCK2 gene has yielded promising results in the treatment of AD. Our previous study indicated that PEG-PEI/siROCK2 could effectively suppress ROCK2 mRNA expression and showed a promising prospect for the treatment of Alzheimer's disease. However, the ability of PEG-PEI/siROCK2 to reduce Aβ-induced cytotoxicity is unknown. To investigate the effect of PEG-PEI/siROCK2 against Aβ42-induced neurotoxicity, primary cultured cortical neurons were pretreated with PEG-PEI/siROCK2 for 24 h and then treated with 5 μM Aβ42 for 24 h. We found that PEG-PEI/siROCK2 increased the cell viability and reduced the number of apoptotic cells induced by Aβ42, as measured using an MTT assay and Annexin V/PI staining. A further study revealed that PEG-PEI/siROCK2 can activate p-Akt, and treatment with the PI3K inhibitor LY294002 attenuated the neuroprotective effects. These results suggest that PEG-PEI/siROCK2 prevents Aβ42-induced neurotoxicity and that the activation of PI3K/Akt pathway is involved in neuroprotection. Taken together, these findings shed light on the role of PEG-PEI/siROCK2 as a potential therapeutic agent for AD.

  6. Linking basin-scale and pore-scale gas hydrate distribution patterns in diffusion-dominated marine hydrate systems

    Science.gov (United States)

    Nole, Michael; Daigle, Hugh; Cook, Ann E.; Hillman, Jess I. T.; Malinverno, Alberto

    2017-02-01

    The goal of this study is to computationally determine the potential distribution patterns of diffusion-driven methane hydrate accumulations in coarse-grained marine sediments. Diffusion of dissolved methane in marine gas hydrate systems has been proposed as a potential transport mechanism through which large concentrations of hydrate can preferentially accumulate in coarse-grained sediments over geologic time. Using one-dimensional compositional reservoir simulations, we examine hydrate distribution patterns at the scale of individual sand layers (1-20 m thick) that are deposited between microbially active fine-grained material buried through the gas hydrate stability zone (GHSZ). We then extrapolate to two-dimensional and basin-scale three-dimensional simulations, where we model dipping sands and multilayered systems. We find that properties of a sand layer including pore size distribution, layer thickness, dip, and proximity to other layers in multilayered systems all exert control on diffusive methane fluxes toward and within a sand, which in turn impact the distribution of hydrate throughout a sand unit. In all of these simulations, we incorporate data on physical properties and sand layer geometries from the Terrebonne Basin gas hydrate system in the Gulf of Mexico. We demonstrate that diffusion can generate high hydrate saturations (upward of 90%) at the edges of thin sands at shallow depths within the GHSZ, but that it is ineffective at producing high hydrate saturations throughout thick (greater than 10 m) sands buried deep within the GHSZ. Furthermore, we find that hydrate in fine-grained material can preserve high hydrate saturations in nearby thin sands with burial.Plain Language SummaryThis study combines one-, two-, and three-dimensional simulations to explore one potential process by which methane dissolved in water beneath the seafloor can be converted into solid methane hydrate. This work specifically examines one end-member methane transport

  7. Hydration rate of obsidian.

    Science.gov (United States)

    Friedman, I; Long, W

    1976-01-30

    The hydration rates of 12 obsidian samples of different chemical compositions were measured at temperatures from 95 degrees to 245 degrees C. An expression relating hydration rate to temperature was derived for each sample. The SiO(2) content and refractive index are related to the hydration rate, as are the CaO, MgO, and original water contents. With this information it is possible to calculate the hydration rate of a sample from its silica content, refractive index, or chemical index and a knowledge of the effective temperature at which the hydration occurred. The effective hydration temperature can be either measured or approximated from weather records. Rates have been calculated by both methods, and the results show that weather records can give a good approximation to the true EHT, particularly in tropical and subtropical climates. If one determines the EHT by any of the methods suggested, and also measures or knows the rate of hydration of the particular obsidian used, it should be possible to carry out absolute dating to +/- 10 percent of the true age over periods as short as several years and as long as millions of years.

  8. Stabilization of Candida antarctica Lipase B (CALB Immobilized on Octyl Agarose by Treatment with Polyethyleneimine (PEI

    Directory of Open Access Journals (Sweden)

    Sara Peirce

    2016-06-01

    Full Text Available Lipase B from Candida antarctica (CALB was immobilized on octyl agarose (OC and physically modified with polyethyleneimine (PEI in order to confer a strong ion exchange character to the enzyme and thus enable the immobilization of other enzymes on its surface. The enzyme activity was fully maintained during the coating and the thermal stability was marginally improved. The enzyme release from the support by incubation in the non-ionic detergent Triton X-100 was more difficult after the PEI-coating, suggesting that some intermolecular physical crosslinking had occurred, making this desorption more difficult. Thermal stability was marginally improved, but the stability of the OCCALB-PEI was significantly better than that of OCCALB during inactivation in mixtures of aqueous buffer and organic cosolvents. SDS-PAGE analysis of the inactivated biocatalyst showed the OCCALB released some enzyme to the medium during inactivation, and this was partially prevented by coating with PEI. This effect was obtained without preventing the possibility of reuse of the support by incubation in 2% ionic detergents. That way, this modified CALB not only has a strong anion exchange nature, while maintaining the activity, but it also shows improved stability under diverse reaction conditions without affecting the reversibility of the immobilization.

  9. Molecular modeling of the dissociation of methane hydrate in contact with a silica surface.

    Science.gov (United States)

    Bagherzadeh, S Alireza; Englezos, Peter; Alavi, Saman; Ripmeester, John A

    2012-03-15

    We use constant energy, constant volume (NVE) molecular dynamics simulations to study the dissociation of the fully occupied structure I methane hydrate in a confined geometry between two hydroxylated silica surfaces between 36 and 41 Å apart, at initial temperatures of 283, 293, and 303 K. Simulations of the two-phase hydrate/water system are performed in the presence of silica, with and without a 3 Å thick buffering water layer between the hydrate phase and silica surfaces. Faster decomposition is observed in the presence of silica, where the hydrate phase is prone to decomposition from four surfaces, as compared to only two sides in the case of the hydrate/water simulations. The existence of the water layer between the hydrate phase and the silica surface stabilizes the hydrate phase relative to the case where the hydrate is in direct contact with silica. Hydrates bound between the silica surfaces dissociate layer-by-layer in a shrinking core manner with a curved decomposition front which extends over a 5-8 Å thickness. Labeling water molecules shows that there is exchange of water molecules between the surrounding liquid and intact cages in the methane hydrate phase. In all cases, decomposition of the methane hydrate phase led to the formation of methane nanobubbles in the liquid water phase.

  10. 适用于高温高矿化度条件的聚乙烯亚胺冻胶堵水剂%Water shutoff agent of PEI gel applicable to high temperature and high salinity reservoirs

    Institute of Scientific and Technical Information of China (English)

    吴运强; 毕岩滨; 纪萍; 汪进; 贾寒; 周洪涛

    2015-01-01

    A gel type shutoff agent with anionic polyacrylamide as a main agent required for high temperature and high salinity formation water shutoff was developed using a crosslinking agent of water soluble polymer-polyethylenimine (PEI), and protective agent was added to slow down hydrolysis of the main agent under high temperature. The impact of main agent mass fraction, main agent molecular weight, PEI mass fraction, PEI molecular weight, salinity and pH was experimentally investigated on gelling performance of PEI gel. Experimental results show that the relative molecular weights of main agent and PEI increase as the mass fraction of main agent and PEI increases while the gelation time is shortened. But under high mass fraction, excessive crosslinking is more likely to occur, causing premature gel dehydration. The gelation time is shortened with the increase of pH values, and becomes longer with the increase of salinity. At 110℃, for formation water with NaCl content of 50 000 mg / L, the gel shows high strength and good resistance to temperature and good blocking effectiveness, and remains hydrated for at least 120 days. The optimum formula for water shutoff system is 0.6% to 0.8% anionic polyacrylamide & 0.3% to 0.7% PEI & 0.8% to 1% high temperature protective agent.%针对高温高矿化度地层堵水需求,研制了一种耐高温高矿化度的以阴离子聚丙烯酰胺为主剂的冻胶型堵剂,交联剂采用水溶性聚合物聚乙烯亚胺(PEI),并加入保护剂减缓高温下主剂的水解。实验考察了主剂质量分数、主剂分子量、PEI质量分数、PEI分子量、矿化度和pH值等因素对PEI冻胶成胶性能的影响。实验结果表明:随着主剂和PEI相对分子质量增加,主剂和PEI质量分数的增加,成胶时间缩短,但交联剂质量分数过高易发生过交联现象,造成冻胶过早脱水;成胶时间随着pH值的增加而缩短,随矿化度的增加而变长。在110℃条

  11. Hydrate morphology: Physical properties of sands with patchy hydrate saturation

    Science.gov (United States)

    Dai, S.; Santamarina, J.C.; Waite, William F.; Kneafsey, T.J.

    2012-01-01

    The physical properties of gas hydrate-bearing sediments depend on the volume fraction and spatial distribution of the hydrate phase. The host sediment grain size and the state of effective stress determine the hydrate morphology in sediments; this information can be used to significantly constrain estimates of the physical properties of hydrate-bearing sediments, including the coarse-grained sands subjected to high effective stress that are of interest as potential energy resources. Reported data and physical analyses suggest hydrate-bearing sands contain a heterogeneous, patchy hydrate distribution, whereby zones with 100% pore-space hydrate saturation are embedded in hydrate-free sand. Accounting for patchy rather than homogeneous hydrate distribution yields more tightly constrained estimates of physical properties in hydrate-bearing sands and captures observed physical-property dependencies on hydrate saturation. For example, numerical modeling results of sands with patchy saturation agree with experimental observation, showing a transition in stiffness starting near the series bound at low hydrate saturations but moving toward the parallel bound at high hydrate saturations. The hydrate-patch size itself impacts the physical properties of hydrate-bearing sediments; for example, at constant hydrate saturation, we find that conductivity (electrical, hydraulic and thermal) increases as the number of hydrate-saturated patches increases. This increase reflects the larger number of conductive flow paths that exist in specimens with many small hydrate-saturated patches in comparison to specimens in which a few large hydrate saturated patches can block flow over a significant cross-section of the specimen.

  12. Wet hydrate dissolution plant

    OpenAIRE

    Stanković Mirjana S.; Kovačević Branimir T.; Pezo Lato L.

    2003-01-01

    The IGPC Engineering Department designed basic projects for a wet hydrate dissolution plant, using technology developed in the IGPC laboratories. Several projects were completed: technological, machine, electrical, automation. On the basis of these projects, a production plant with capacity of 50,000 t/y was manufactured, at "Zeolite Mira", Mira (VE), Italy, in 1997, for increasing detergent zeolite production from 50,000 to 100,000 t/y. Several goals were realized by designing a wet hydrate ...

  13. Estimation of gas hydrate saturation with temperature calculated from hydrate threshold at C0002 during IODP NanTroSEIZE Stage 1 expeditions in the Nankai Trough

    Science.gov (United States)

    Miyakawa, A.; Yamada, Y.; Saito, S.; Bourlange, S.; Chang, C.; Conin, M.; Tomaru, H.; Kinoshita, M.; Tobin, H.; 314/315/316Scientists, E.

    2008-12-01

    During the IODP Expedition 314, conducted at Nankai trough accretionary prism, gas hydrate was observed at Site C0002. Gas hydrate beneath seafloor is promising energy source and potentially hazardous material during drilling. The precise estimation of gas hydrate saturation is important, but previous works have not considered the effect" of the in-situ temperature. In this study, we propose an estimation method of gas hydrate saturation with temperature calculated from threshold of gas hydrate. Gas hydrate saturation was determined based on the Logging While Drilling (LWD) Expedition 314 data. The gas hydrate bearing zone was located between 218.1 to 400.4 m below seafloor. Archie's relation was used to estimate gas hydrate saturation. This relation requires the porosity, the sea water resistivity and formation resistivity. We determined porosity to be between ~70 to ~30% based on density log. Since the resistivity of sea water is temperature dependent, temperature profile (calculated temperature model) was determined from the thermal conductivity and the temperature at the base of the gas hydrate. In our calculated temperature model, the saturation increases from ~10% at ~220m to ~30% at 400 m below sea floor. Spikes that have a maximum value at 80% at sand layers were observed. We also estimated the gas hydrate saturation from the constant temperature profile in 12°C (temperature constant model). This resulted in almost constant saturation (~15%) with the high saturation spikes. We compared these saturations with the hydrate occupation ratio within sand layers derived from RAB image. The hydrate occupation ratio shows increasing trend with increasing depth, and this trend is similar to the gas hydrate saturation with the calculated temperature model. This result suggests that the temperature profile should be considered to obtain precise gas hydrate saturation. Since the high sedimentation rate can affect thermal condition, we are planning to estimate the

  14. Receptor-mediated gene delivery using polyethylenimine (PEI)coupled with polypeptides targeting FGF receptors on cells surface

    Institute of Scientific and Technical Information of China (English)

    LI Da; WANG Qing-qing; TANG Gu-ping; HUANG Hong-liang; SHEN Fen-ping; LI Jing-zhong; YU Hai

    2006-01-01

    Objective: To construct a novel kind ofnonviral gene delivery vector based on polyethylenimine (PEI) conjugated with polypeptides derived from ligand FGF with high transfection efficiency and according to tumor targeting ability. Methods:The synthetic polypeptides CR16 for binding FGF receptors was conjugated to PEI and the characters of the polypeptides including DNA condensing and particle size were determined. Enhanced efficiency and the targeting specificity of the synthesized vector were investigated in vitro and in vivo. Results: The polypeptides were successfully coupled to PEI. The new vectors PEI-CR16 could efficiently condense pDNA into particles with around 200 nm diameter. The PEI-CR16/pDNA polyplexes showed significantly greater transgene activity than PEI/pDNA in FGF receptors positive tumor cells in vitro and in vivo gene transfer, while no difference was observed in FGF receptors negative tumor cells. The enhanced transfection efficiency of PEI-CR16 could be blocked by excess free polypeptides. Conclusion: The synthesized vector could improve the efficiency of gene transfer and targeting specificity in FGF receptors positive cells. The vector had good prospect for use in cancer gene therapy.

  15. Amiloidose renal em cão Shar-Pei: Relato de Caso Renal amyloidosis in a Shar-Pei dog: A case report

    Directory of Open Access Journals (Sweden)

    J.L. Reis Jr.

    2001-08-01

    Full Text Available O presente relato descreve os achados clínicos e anatomopatológicos de um caso de amiloidose renal em um cão macho de nove anos da raça Shar-Pei. O animal apresentava quadro clínico de esporotricose e de insuficiência renal e exames positivos para erlichiose e leishmaniose. No dia anterior ao óbito, o cão apresentou apatia, desidratação e anúria. À necropsia foram observados inúmeros pontos milimétricos esbranquiçados localizados no córtex renal e hepatização do lobo diafragmático esquerdo. O achado histológico mais importante foi deposição de material eosinofílico, amorfo e acelular localizado nos tufos glomerulares que se corou positivamente pelo vermelho congo (amilóide. Observaram-se nefrite supurada multifocal, espessamento da cápsula de Bowman e broncopneumonia supurada crônica, com fibrose intensa. A origem da amiloidose, no presente caso, poderia ser hereditária, assemelhando-se à amiloidose familiar descrita em cães da raça Shar-Pei, ou ser devida à inflamação supurada crônica e/ou leishmaniose.The clinical and pathological findings of a case of renal amyloidosis in a nine-year-old male Shar-Pei dog were described. Clinically, there were signs of sporotrichosis and renal insufficiency, besides being positive to leishmaniasis and ehrlichiosis. On the day before death, the animal became apathetic, dehydrated and anuric. On gross examination, there were several whitish millimetric spots seen widespread in both renal cortices and consolidation of the left diaphragmatic pulmonary lobe. The most important microscopic finding was a deposition of amorphous acellular material on the glomerular tufts which stained positively by congo red stain. Other changes were multifocal suppurative nephritis, thickening of the Bowman capsule and chronic suppurative bronchopneumonia. The origin of the amyloidosis in this case could be hereditary, being similar to familiar amyloidosis described in Shar-Pei breed, or due to

  16. Carboxymethylcellulose (CMC) formed nanogels with branched poly(ethyleneimine) (bPEI) for inhibition of cytotoxicity in human MSCs as a gene delivery vehicles.

    Science.gov (United States)

    Yang, Han Na; Park, Ji Sun; Jeon, Su Yeon; Park, Keun-Hong

    2015-05-20

    Specific vehicles are necessary for safe and efficient gene transfection into cells. Nano-type hydrogels (nanogel) comprising carboxymethylcellulose (CMC) complexed with branched type cationic poly(ethleneimine) (bPEI) were used as gene delivery vehicles. When complexes of CMC and bPEI were used in vitro, CMC showed nano-gel type properties, as shown by the results of a viscosity test, and bPEI showed low cytotoxicity comparing to bPEI alone. Together, these properties are shown to maintain high gene transfection efficiency. In viability experiments using three types of adult stem cells, cell viability varied depending on the branch form of PEI and whether or not it is in a complex with CMC. The gene delivery efficacy showed that the CMC nanogel complexed with bPEI (CMC-bPEI) showed more uptaking and gene transfection ability in hMSCs comparing to bPEI alone. In osteogenesis, the CMC-bPEI complexed with OSX pDNA showed more easy internalization than bPEI alone complexed with OSX pDNA in hMSCs. Specific genes and proteins related in osteogenic differentiation were expressed in hMSCs when the CMC-bPEI complexed with OSX pDNA was used.

  17. Simulation of gas hydrate dissociation caused by repeated tectonic uplift events

    Science.gov (United States)

    Goto, Shusaku; Matsubayashi, Osamu; Nagakubo, Sadao

    2016-05-01

    Gas hydrate dissociation by tectonic uplift is often used to explain geologic and geophysical phenomena, such as hydrate accumulation probably caused by hydrate recycling and the occurrence of double bottom-simulating reflectors in tectonically active areas. However, little is known of gas hydrate dissociation resulting from tectonic uplift. This study investigates gas hydrate dissociation in marine sediments caused by repeated tectonic uplift events using a numerical model incorporating the latent heat of gas hydrate dissociation. The simulations showed that tectonic uplift causes upward movement of some depth interval of hydrate-bearing sediment immediately above the base of gas hydrate stability (BGHS) to the gas hydrate instability zone because the sediment initially maintains its temperature: in that interval, gas hydrate dissociates while absorbing heat; consequently, the temperature of the interval decreases to that of the hydrate stability boundary at that depth. Until the next uplift event, endothermic gas hydrate dissociation proceeds at the BGHS using heat mainly supplied from the sediment around the BGHS, lowering the temperature of that sediment. The cumulative effects of these two endothermic gas hydrate dissociations caused by repeated uplift events lower the sediment temperature around the BGHS, suggesting that in a marine area in which sediment with a highly concentrated hydrate-bearing layer just above the BGHS has been frequently uplifted, the endothermic gas hydrate dissociation produces a gradual decrease in thermal gradient from the seafloor to the BGHS. Sensitivity analysis for model parameters showed that water depth, amount of uplift, gas hydrate saturation, and basal heat flow strongly influence the gas hydrate dissociation rate and sediment temperature around the BGHS.

  18. Optimization of Adsorption Conditions of Cr (VI by PEI Modified BSG Using Response Surface Methodology

    Directory of Open Access Journals (Sweden)

    Xinlong Jiang

    2015-02-01

    Full Text Available Surface response optimization of Adsorption Conditions of Cr (VI wastewater by PEI modified brewer's grains (BSG with the factors of pH value, adsorbent concentration, adsorption time, amount of adsorbent and the response of adsorption rate were studied. The optimal parameters for adsorption conditions were of adsorbent concentration of 113.30 mg/L, adsorbent particle size of 60~80 mesh, pH 1.79, adsorbent amount of 4.99 g/L, adsorption time and temperature of 1.88 h and 30°C, respectively. The maximal absorption rate got 100.0%, adsorption capacity was 46.58 mg/g. The PEI modified BSG is a promising, cheap, efficient, new biological materials of adsorption for Cr (VI in wastewater.

  19. Synthesis Technology of PEI Modified Brewer's Grains for the Adsorption of Cr(VI

    Directory of Open Access Journals (Sweden)

    Yihua Jiang

    2015-05-01

    Full Text Available With beer production waste brewer's grains (BSG as the raw material, through polyethylenimine (PEI modified and glutaraldehyde (GA cross-linking process for preparing the modified brewer's grains biosorbents. The simulation of Cr (VI wastewater as treatment object, through the optimization of synthesis conditions of Cr (VI, the optimal synthesis process was obtained. The results showed, 4 g BSG and 100 mL 4% PEI methanol solution were placed in 250 mL conical flask at room temperature, shaking for 24 h. After the mixture,shifted to 200 mL l.5% GA solution directly, magnetic stirring for half an hour, the modified results of brewer’s grain was best. Under the optimal conditions, the average of adsorption rate was 98.82% and adsorption capacity was 45.31 mg/g. The modified brewer's grains of amine surfactant modified is a promising treatment of chromium wastewater biological materials.

  20. Back pain and body posture evaluation instrument (BackPEI): development, content validation and reproducibility.

    Science.gov (United States)

    Noll, Matias; Tarragô Candotti, Cláudia; Vieira, Adriane; Fagundes Loss, Jefferson

    2013-08-01

    Following a search conducted in several databases, no instrument was found that jointly evaluates the prevalence of back pain and its associated demographic, social-economic, hereditary, behavioral and postural risk factors. Thus, the present study aims to develop the Back Pain and Body Posture Evaluation Instrument (BackPEI) for school-age children and verify its validity and reproducibility. Twenty-one questions were elaborated to compose the BackPEI instrument, eight experts checked the content validity, and its reproducibility was tested by applying the questionnaire to 260 primary schoolchildren, at two different times with a 7-day interval. The reproducibility data for the first 20 questions, analyzed using the kappa (k) coefficient, were classified as "very good" (k > 0.8) or "good" (0.6 back pain and its associated risk factors.

  1. STRUCTURE AND THERMAL MECHANICAL PROPERTIES OF ORIENTED POLYIMIDE (PEI-E)

    Institute of Scientific and Technical Information of China (English)

    SUN Zhenhua; ZHUANG Yugang; LI Shichun; DING Mengxian; FENG Zhiliu

    1992-01-01

    The strain induced crystallization behaviour in polyimide from 1 , 4-bis (3 ', 4 '- dicarboxyphenoxy)benzene and 4,4'-oxydianiline (PEI-E)has been investigated by WAXD, DSC and FTIR. The results obtained show that crystallization in PEI-E did take place just after tensile yielding. Meanwhile, the effect of strain induced crystallization on the thermomechanical properties was studied by DMA and TMA, the results of which indicate that the crystallization and hot stretching have a certain influence on the dynamic mechanical properties, such as weakening the β relaxation and decreasing the glass transition temperature. The TMA results confirm the shifting of glass transition temperature to lower temperature region after hot stretching. This phenomenon could be well explained by the effect of residual stress according to Eyring's theory.

  2. Resistance welding of carbon fibre reinforced polyetheretherketone composites using metal mesh and PEI film

    Institute of Scientific and Technical Information of China (English)

    闫久春; 王晓林; 秦明; 赵新英; 杨士勤

    2004-01-01

    Weldability of polyetheretherketone(PEEK) with polyetherimide(PEI) is tested. And carbon fiber reinforced PEEK laminates are resistance welded using stainless steel mesh heating element. The effects of the welding time and welding pressure on the lap shear strength of joints are investigated. Results show that PEEK can heal with PEI well in welding condition and the lap shear strength of PEEK/CF(carbon fibre) joint increases linearly with welding time, but reaches a maximum value when welding pressure ranging from 0.3MPa to 0.5MPa with constant welding time. The fracture characteristics of surface are analyzed by SEM techniques, and four types of fracture modes of lap shear joints are suggested.

  3. Henry Moore’s Public Sculpture in the US: The Collaborations with I. M. Pei

    Directory of Open Access Journals (Sweden)

    Alex Potts

    2016-07-01

    Full Text Available The many commissions Henry Moore received for public sculpture in the United States provided the occasion for several quite distinctive works. While not site specific, these were unique, and their final form, scale, and disposition was elaborated with a particular setting in mind. This aspect of Moore’s work in the US, which began with the monumental piece he designed for the Lincoln Center in New York in 1963–65, is examined here by focusing on the productive relationship he forged with the architect I. M. Pei in the 1970s. The sculptures Moore produced in collaboration with Pei respond in suggestive ways to the spatial environments created in American cities by late modern architectural developments. They also realize an oddly effective combination of the biomorphic and abstract that differs both from the bodily conception of Moore’s earlier work and the non-figurative character of much public sculpture of the time.

  4. Layer-by-layer assembly surface modified microbial biomass for enhancing biorecovery of secondary gold.

    Science.gov (United States)

    Zhou, Ying; Zhu, Nengwu; Kang, Naixin; Cao, Yanlan; Shi, Chaohong; Wu, Pingxiao; Dang, Zhi; Zhang, Xiaoping; Qin, Benqian

    2017-02-01

    Enhancement of the biosorption capacity for gold is highly desirable for the biorecovery of secondary gold resources. In this study, polyethylenimine (PEI) was grafted on Shewanella haliotis surface through layer-by-layer assembly approach so as to improve the biosorption capacity of Au(III). Results showed that the relative contribution of amino group to the biosorption of Au(III) was the largest one (about 44%). After successful grafting 1, 2 and 3-layer PEI on the surface of biomass, the biosorption capacity significantly enhanced from 143.8mg/g to 597.1, 559.1, and 536.8mg/g, respectively. Interestingly, the biomass modified with 1-layer PEI exhibited 4.2 times higher biosorption capacity than the untreated control. When 1-layer modified biomass was subjected to optimizing the various conditions by response surface methodology, the theoretical maximum adsorption capacity could reach up to 727.3mg/g. All findings demonstrated that PEI modified S. haliotis was effective for enhancing gold biorecovery.

  5. Hydration behaviour of polyhydroxylated fullerenes

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Zavala, J G [Departamento de Ciencias Exactas y Tecnologicas, Centro Universitario de Los Lagos, Universidad de Guadalajara, Enrique Diaz de Leon S/N, 47460 Jalisco (Mexico); Barajas-Barraza, R E [Departamento de Matematicas y Fisica, Instituto Tecnologico y de Estudios Superiores de Occidente, Periferico Sur, Manuel Gomez MorIn No 8585, 45604 Jalisco (Mexico); Padilla-Osuna, I; Guirado-Lopez, R A, E-mail: jgrz@culagos.udg.mx, E-mail: ebarajas@iteso.mx, E-mail: ismael@ifisica.uaslp.mx, E-mail: guirado@ifisica.uaslp.mx [Instituto de Fisica ' Manuel Sandoval Vallarta' , Universidad Autonoma de San Luis Potosi, Alvaro Obregon 64, 78000 San Luis Potosi (Mexico)

    2011-10-28

    We have performed semi-empirical as well as density functional theory calculations in order to analyse the hydration properties of both bare C{sub 60} and highly hydroxylated C{sub 60}(OH){sub 26} fullerenes. In all of our calculations, a total of 42 and 98 water molecules are always surrounding our here-considered carbon nanostructures. We found different wetting properties as a function of the chemical composition and structure of the OH-molecular over-layer covering the fullerene surface. In the case of bare C{sub 60}, water adsorption reveals that the H{sub 2}O species are not uniformly arranged around the carbon network but rather forms water droplets of different sizes, clearly revealing the hydrophobic nature of the C{sub 60} structure. In contrast, in the polyhydroxylated C{sub 60}(OH){sub 26} fullerenes, the degree of wetting is strongly influenced by the precise location of the hydroxyl groups. We found that different adsorbed configurations for the OH-molecular coating can lead to the formation of partially hydrated or completely covered C{sub 60}(OH){sub 26} compounds, a result that could be used to synthesize fullerene materials with different degrees of wettability. By comparing the relative stability of our hydroxylated structures in both bare and hydrated conditions we obtain that the energy ordering of the C{sub 60}(OH){sub 26} isomers can change in the presence of water. The radial distribution function of our hydrated fullerenes reveals that water near these kinds of surfaces is densely packed. In fact, by counting the number of H{sub 2}O molecules which are adsorbed, by means of hydrogen bonds, to the surface of our more stable C{sub 60}(OH){sub 26} isomer, we found that it varies in the range of 5-10, in good agreement with experiments. Finally, by comparing the calculated optical absorption spectra of various C{sub 60}(OH){sub 26} structures in the presence and absence of water molecules, we note that only slight variations in the position and

  6. Ag/Pd纳米复合自组装膜的制备与电催化性质%Preparation of Ag/Pd Nanocomposite Thin Films by Layer-by-Layer Assembly Technique and Their Electrocatalytic Properties

    Institute of Scientific and Technical Information of China (English)

    张莉; 王聪; 王红艳; 张超

    2012-01-01

    利用层层静电自组装技术将聚乙烯亚胺(PEI-Ag+)、PdCl42-交替沉积在基底上,然后用硼氢化钠还原,构筑了含银/钯复合纳米粒子的PEI-Ag/Pd纳米复合薄膜.通过扫描电子显微镜(FESEM),X射线光电子能谱(XPS)和循环伏安(CV)等手段对复合膜的成分、微结构和性质进行了测试分析.膜上生成了不规则和立方体状的银/钯纳米复合物,导致膜表面有一定的粗糙度.结果表明,双金属{PEI-Ag/Pd}n复合膜比单金属{PEI/Pd}n或{PEI-Ag/PSS}n膜对多巴胺的氧化有更好的电催化活性.%Nanocomposite thin films containing Ag/Pd nanoparticles PEI-Ag/Pd were formed by alternating adsorption of PEI-Ag+ and PdCl42- by a layer-by-layer self-assembly technique and subsequent postdeposition reduction by sodium borohydride (NaBH4). The composition, microstructure and properties were characterized by field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). The Ag/Pd nanocomposites which are irregular and cubic are formed in the films, resulting in a rough surface of the composite film. The results indicate that the {PEI-Ag/Pd}n nanocomposite film exhibits better electrocatalytic activity for the oxidation of dopamine than {PEI/Pd}n and {PEI-Ag/PSS}n films.

  7. Algae harvesting for biofuel production: influences of UV irradiation and polyethylenimine (PEI) coating on bacterial biocoagulation.

    Science.gov (United States)

    Agbakpe, Michael; Ge, Shijian; Zhang, Wen; Zhang, Xuezhi; Kobylarz, Patricia

    2014-08-01

    There is a pressing need to develop efficient and sustainable separation technologies to harvest algae for biofuel production. In this work, two bacterial species (Escherichia coli and Rhodococus sp.) were used as biocoagulants to harvest Chlorella zofingiensis and Scenedesmus dimorphus. The influences of UV irradiation and polyethylenimine (PEI)-coating on the algal harvesting efficiency were investigated. Results showed that the UV irradiation could slightly enhance bacteria-algae biocoagulation and algal harvesting efficiency. In contrast, the PEI-coated E. coli cells noticeably increased the harvesting efficiencies from 23% to 83% for S. dimorphus when compared to uncoated E. coli cells. Based on the soft-particle Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, an energy barrier existed between uncoated E. coli cells and algal cells, whereas the PEI coating on E. coli cells eliminated the energy barrier, thereby the biocoagulation was significantly improved. Overall, this work presented groundwork toward the potential use of bacterial biomass for algal harvesting from water. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Polyethyleneimine (PEI mediated siRNA gene silencing in the Schistosoma mansoni snail host, Biomphalaria glabrata.

    Directory of Open Access Journals (Sweden)

    Matty Knight

    2011-07-01

    Full Text Available An in vivo, non-invasive technique for gene silencing by RNA interference (RNAi in the snail, Biomphalaria glabrata, has been developed using cationic polymer polyethyleneimine (PEI mediated delivery of long double-stranded (ds and small interfering (si RNA. Cellular delivery was evaluated and optimized by using a 'mock' fluorescent siRNA. Subsequently, we used the method to suppress expression of Cathepsin B (CathB with either the corresponding siRNA or dsRNA of this transcript. In addition, the knockdown of peroxiredoxin (Prx at both RNA and protein levels was achieved with the PEI-mediated soaking method. B. glabrata is an important snail host for the transmission of the parasitic digenean platyhelminth, Schistosoma mansoni that causes schistosomiasis in the neotropics. Progress is being made to realize the genome sequence of the snail and to uncover gene expression profiles and cellular pathways that enable the snail to either prevent or sustain an infection. Using PEI complexes, a convenient soaking method has been developed, enabling functional gene knockdown studies with either dsRNA or siRNA. The protocol developed offers a first whole organism method for host-parasite gene function studies needed to identify key mechanisms required for parasite development in the snail host, which ultimately are needed as points for disrupting this parasite mediated disease.

  9. Preparation and characterization of PEG-PEI/Fe3O4 nano-magnetic fluid by co-precipitation method

    Institute of Scientific and Technical Information of China (English)

    PENG Jian; ZOU Fen; LIU Lu; TANG Liang; YU Li; CHEN Wei; LIU Hui; TANG Jing-bo; WU Li-xiang

    2008-01-01

    PEG-PEI/Fe3O4 nano-magnetic fluids with different mass fractions of reactant were prepared by co-precipitation method. Besides particle size analyzer, the methods of XRD, IR, VSM and AFM were adopted to characterize the synthesized samples. Covalent bonding of PEG, PEI and Fe3O4 exhibits superparamagnetism. The TEM photograph shows that the particles are of stable dispersion and little aggregation, with smooth surface, spherical shape and a diameter of about 80 nm, which meets the requirements of nano-materials. When the mass fraction of PEI in reactant is 25%, the particle size, Zeta-potential and pEGFP-C1 DNA loading efficiency are all satisfactory. In this case, PEG-PEI/ Fe3O4 nano-magnetic fluids can be used as gene vectors or targeted drug carriers.

  10. PART II. HYDRATED CEMENTS

    Directory of Open Access Journals (Sweden)

    Milan Drabik

    2014-09-01

    Full Text Available Essential focus of the study has been to acquire thermoanalytical events, incl. enthalpies of decompositions - ΔH, of technological materials based on two types of Portland cements. The values of thermoanalytical events and also ΔH of probes of technological compositions, if related with the data of a choice of minerals of calcium-silicate-sulfate-aluminate hydrates, served as a valued input for the assessment of phases present and phase changes due to the topical hydraulic processes. The results indicate mainly the effects of "standard humidity" or "wet storage" of the entire hydration/hydraulic treatment, but also the presence of cement residues alongside calcium-silicate-sulfate-aluminate hydrates (during the tested period of treatment. "A diluting" effect of unhydrated cement residues upon the values of decomposition enthalpies in the studied multiphase system is postulated and discussed

  11. Obsidian hydration profile measurements using a nuclear reaction technique

    Science.gov (United States)

    Lee, R.R.; Leich, D.A.; Tombrello, T.A.; Ericson, J.E.; Friedman, I.

    1974-01-01

    AMBIENT water diffuses into the exposed surfaces of obsidian, forming a hydration layer which increases in thickness with time to a maximum depth of 20-40 ??m (ref. 1), this layer being the basic foundation of obsidian dating2,3. ?? 1974 Nature Publishing Group.

  12. Studies on preparing and adsorption property of grafting terpolymer microbeads of PEI-GMA/AM/MBA for bilirubin.

    Science.gov (United States)

    Gao, Baojiao; Lei, Haibo; Jiang, Liding; Zhu, Yong

    2007-06-15

    Crosslinking copolymer microbeads with a diameter range of 100-150 microm were synthesized by suspension copolymerization of glycidyl methacrylate (GMA), acrylamide (AM) and N,N'-methylene bisacrylamide (MBA). Subsequently, polyethyleneimine (PEI) was grafted on the surfaces of the terpolymer microbeads GMA/AM/MBA via the ring-opening reaction of the epoxy groups, and the grafting microbeads PEI-GMA/AM/MBA were prepared. In this paper, the adsorption property of the grafting microbeads for bilirubin was mainly investigated, and the effects of various factors, such as pH value, ionic strength and grafting degree of PEI on the surface of grafting microbeads and the adsorption capacity of the grafting microbeads for bilirubin were examined. The batch adsorption experiment results show that by right of the action of grafted polyamine macromolecules PEI, the grafting microbeads PEI-GMA/AM/MBA have quite strong adsorption ability for bilirubin; the isotherm adsorption conforms to Freundlich equation. The pH value of the medium affects the adsorption capacity greatly, As in the nearly neutral solutions with pH 6, the grafting microbeads have the strongest adsorption ability for bilirubin, whereas in acidic and basic solutions their adsorption ability is weak. The ionic strength hardly affects the adsorption ability of the grafting microbeads. The grafting degree of PEI on the surfaces of the grafting microbeads also has a great effect on the adsorption capacity, and higher the grafting degree of PEI on the surface of the microbead PEI-GMA/AM/MBA, the stronger is the adsorption ability of the microbeads.

  13. Effect of pH on the structure and drug release profiles of layer-by-layer assembled films containing polyelectrolyte, micelles, and graphene oxide

    Science.gov (United States)

    Han, Uiyoung; Seo, Younghye; Hong, Jinkee

    2016-04-01

    Layer by layer (lbl) assembled multilayer thin films are used in drug delivery systems with attractive advantages such as unlimited selection of building blocks and free modification of the film structure. In this paper, we report the fundamental properties of lbl films constructed from different substances such as PS-b-PAA amphiphilic block copolymer micelles (BCM) as nano-sized drug vehicles, 2D-shaped graphene oxide (GO), and branched polyethylenimine (bPEI). These films were fabricated by successive lbl assembly as a result of electrostatic interactions between the carboxyl group of BCM and amine group of functionalized GO or bPEI under various pH conditions. We also compared the thickness, roughness, morphology and degree of adsorption of the (bPEI/BCM) films to those in the (GO/BCM) films. The results showed significant difference because of the distinct pH dependence of each material. In addition, drug release rates of the GO/BCM film were more rapid those of the (bPEI/BCM) film in pH 7.4 and pH 2 PBS buffer solutions. In (bPEI/BCM/GO/BCM) film, the inserted GO layers into bPEI/BCM multilayer induced rapid drug release. We believe that these materials & pH dependent film properties allow developments in the control of coating techniques for biological and biomedical applications.

  14. Evaluation of Gas Hydrate at Alaminos Canyon 810, Northern Gulf of Mexico Slope

    Science.gov (United States)

    Yang, C.; Cook, A.; Sawyer, D.; Hillman, J. I. T.

    2016-12-01

    trace, a high velocity layer was required below the base of hydrate stability, which is not indicated by the well logs. Our models indicate that at AC810, Hydrate Unit A probably contains hydrate filled fractures in a marine mud. For Hydrate Unit B, our models suggest hydrate may occur in a sand-prone interval, but is more likely to be gas hydrate filled fractures in marine mud.

  15. Bioreducible PEI-siRNA Nanocomplex for Liver Cancer Therapy: Transfection, Biodistribution, and Tumor Growth Inhibition In Vivo

    Directory of Open Access Journals (Sweden)

    Wei Xia

    2013-01-01

    Full Text Available A bioreducible polyethylenimine (SS-PEI was successfully applied as a nonviral carrier for the delivery of plasmid DNA and VEGF-siRNA in vitro and in vivo. The SS-PEI could strongly condense DNA or siRNA into nanosized complexes (below 200 nm with positive surface charges. In vitro transfection experiments using GFP plasmid as gene reporter showed that the complexes of SS-PEI/DNA were able to efficiently transfect HepG2 cells, with efficiency comparable to that of polyethylenimine, a gold standard for nonviral gene delivery. Moreover, the complexes of SS-PEI/VEGF-siRNA could lead to reduced levels of VEGF protein in HepG2 cells in vitro. Treatment with the complexes of SS-PEI/VEGF-siRNA efficiently inhibited HepG2 tumor growth in an xenograft mouse model. The data of this study imply that the SS-PEI is a potent nucleic acid carrier applicable for liver cancer gene therapy.

  16. Erwinia amylovora novel plasmid pEI70: complete sequence, biogeography, and role in aggressiveness in the fire blight phytopathogen.

    Directory of Open Access Journals (Sweden)

    Pablo Llop

    Full Text Available Comparative genomics of several strains of Erwinia amylovora, a plant pathogenic bacterium causal agent of fire blight disease, revealed that its diversity is primarily attributable to the flexible genome comprised of plasmids. We recently identified and sequenced in full a novel 65.8 kb plasmid, called pEI70. Annotation revealed a lack of known virulence-related genes, but found evidence for a unique integrative conjugative element related to that of other plant and human pathogens. Comparative analyses using BLASTN showed that pEI70 is almost entirely included in plasmid pEB102 from E. billingiae, an epiphytic Erwinia of pome fruits, with sequence identities superior to 98%. A duplex PCR assay was developed to survey the prevalence of plasmid pEI70 and also that of pEA29, which had previously been described in several E. amylovora strains. Plasmid pEI70 was found widely dispersed across Europe with frequencies of 5-92%, but it was absent in E. amylovora analyzed populations from outside of Europe. Restriction analysis and hybridization demonstrated that this plasmid was identical in at least 13 strains. Curing E. amylovora strains of pEI70 reduced their aggressiveness on pear, and introducing pEI70 into low-aggressiveness strains lacking this plasmid increased symptoms development in this host. Discovery of this novel plasmid offers new insights into the biogeography, evolution and virulence determinants in E. amylovora.

  17. Erwinia amylovora novel plasmid pEI70: complete sequence, biogeography, and role in aggressiveness in the fire blight phytopathogen.

    Science.gov (United States)

    Llop, Pablo; Cabrefiga, Jordi; Smits, Theo H M; Dreo, Tanja; Barbé, Silvia; Pulawska, Joanna; Bultreys, Alain; Blom, Jochen; Duffy, Brion; Montesinos, Emilio; López, María M

    2011-01-01

    Comparative genomics of several strains of Erwinia amylovora, a plant pathogenic bacterium causal agent of fire blight disease, revealed that its diversity is primarily attributable to the flexible genome comprised of plasmids. We recently identified and sequenced in full a novel 65.8 kb plasmid, called pEI70. Annotation revealed a lack of known virulence-related genes, but found evidence for a unique integrative conjugative element related to that of other plant and human pathogens. Comparative analyses using BLASTN showed that pEI70 is almost entirely included in plasmid pEB102 from E. billingiae, an epiphytic Erwinia of pome fruits, with sequence identities superior to 98%. A duplex PCR assay was developed to survey the prevalence of plasmid pEI70 and also that of pEA29, which had previously been described in several E. amylovora strains. Plasmid pEI70 was found widely dispersed across Europe with frequencies of 5-92%, but it was absent in E. amylovora analyzed populations from outside of Europe. Restriction analysis and hybridization demonstrated that this plasmid was identical in at least 13 strains. Curing E. amylovora strains of pEI70 reduced their aggressiveness on pear, and introducing pEI70 into low-aggressiveness strains lacking this plasmid increased symptoms development in this host. Discovery of this novel plasmid offers new insights into the biogeography, evolution and virulence determinants in E. amylovora.

  18. Hydration index--a better parameter for explaining small molecule hydration in inhibition of ice recrystallization.

    Science.gov (United States)

    Tam, Roger Y; Ferreira, Sandra S; Czechura, Pawel; Chaytor, Jennifer L; Ben, Robert N

    2008-12-24

    Several simple mono- and disaccharides have been assessed for their ability to inhibit ice recrystallization. Two carbohydrates were found to be effective recrystallization inhibitors. D-galactose (1) was the best monosaccharide and D-melibiose (5) was the most active disaccharide. The ability of each carbohydrate to inhibit ice growth was correlated to its respective hydration number reported in the literature. A hydration number reflects the number of tightly bound water molecules to the carbohydrate and is a function of carbohydrate stereochemistry. It was discovered that using the absolute hydration number of a carbohydrate does not allow one to accurately predict its ability to inhibit ice recrystallization. Consequently, we have defined a hydration index in which the hydration number is divided by the molar volume of the carbohydrate. This new parameter not only takes into account the number of water molecules tightly bound to a carbohydrate but also the size or volume of a particular solute and ultimately the concentration of hydrated water molecules. The hydration index of both mono- and disaccharides correlates well with experimentally measured RI activity. C-Linked derivatives of the monosaccharides appear to have RI activity comparable to that of their O-linked saccharides but a more thorough investigation is required. The relationship between carbohydrate concentration and RI activity was shown to be noncolligative and a 0.022 M solution of D-galactose (1) and C-linked galactose derivative (10) inhibited recrystallization as well as a 3% DMSO solution. The carbohydrates examined in this study did not possess any thermal hysteresis activity (selective depression of freezing point relative to melting point) or dynamic ice shaping. As such, we propose that they are inhibiting recrystallization at the interface between bulk water and the quasi liquid layer (a semiordered interface between ice and bulk water) by disrupting the preordering of water.

  19. Simulation of subsea gas hydrate exploitation

    Science.gov (United States)

    Janicki, Georg; Schlüter, Stefan; Hennig, Torsten; Deerberg, Görge

    2014-05-01

    The recovery of methane from gas hydrate layers that have been detected in several subsea sediments and permafrost regions around the world is a promising perspective to overcome future shortages in natural gas supply. Being aware that conventional natural gas resources are limited, research is going on to develop technologies for the production of natural gas from such new sources. Thus various research programs have started since the early 1990s in Japan, USA, Canada, India, and Germany to investigate hydrate deposits and develop required technologies. In recent years, intensive research has focussed on the capture and storage of CO2 from combustion processes to reduce climate impact. While different natural or man-made reservoirs like deep aquifers, exhausted oil and gas deposits or other geological formations are considered to store gaseous or liquid CO2, the storage of CO2 as hydrate in former methane hydrate fields is another promising alternative. Due to beneficial stability conditions, methane recovery may be well combined with CO2 storage in the form of hydrates. Regarding technological implementation many problems have to be overcome. Especially mixing, heat and mass transfer in the reservoir are limiting factors causing very long process times. Within the scope of the German research project »SUGAR« different technological approaches for the optimized exploitation of gas hydrate deposits are evaluated and compared by means of dynamic system simulations and analysis. Detailed mathematical models for the most relevant chemical and physical processes are developed. The basic mechanisms of gas hydrate formation/dissociation and heat and mass transport in porous media are considered and implemented into simulation programs. Simulations based on geological field data have been carried out. The studies focus on the potential of gas production from turbidites and their fitness for CO2 storage. The effects occurring during gas production and CO2 storage within

  20. Hydration dynamics near a model protein surface

    Energy Technology Data Exchange (ETDEWEB)

    Russo, Daniela; Hura, Greg; Head-Gordon, Teresa

    2003-09-01

    The evolution of water dynamics from dilute to very high concentration solutions of a prototypical hydrophobic amino acid with its polar backbone, N-acetyl-leucine-methylamide (NALMA), is studied by quasi-elastic neutron scattering and molecular dynamics simulation for both the completely deuterated and completely hydrogenated leucine monomer. We observe several unexpected features in the dynamics of these biological solutions under ambient conditions. The NALMA dynamics shows evidence of de Gennes narrowing, an indication of coherent long timescale structural relaxation dynamics. The translational water dynamics are analyzed in a first approximation with a jump diffusion model. At the highest solute concentrations, the hydration water dynamics is significantly suppressed and characterized by a long residential time and a slow diffusion coefficient. The analysis of the more dilute concentration solutions takes into account the results of the 2.0M solution as a model of the first hydration shell. Subtracting the first hydration layer based on the 2.0M spectra, the translational diffusion dynamics is still suppressed, although the rotational relaxation time and residential time are converged to bulk-water values. Molecular dynamics analysis shows spatially heterogeneous dynamics at high concentration that becomes homogeneous at more dilute concentrations. We discuss the hydration dynamics results of this model protein system in the context of glassy systems, protein function, and protein-protein interfaces.

  1. [Hydration in clinical practice].

    Science.gov (United States)

    Maristany, Cleofé Pérez-Portabella; Segurola Gurruchaga, Hegoi

    2011-01-01

    Water is an essential foundation for life, having both a regulatory and structural function. The former results from active and passive participation in all metabolic reactions, and its role in conserving and maintaining body temperature. Structurally speaking it is the major contributer to tissue mass, accounting for 60% of the basis of blood plasma, intracellular and intersticial fluid. Water is also part of the primary structures of life such as genetic material or proteins. Therefore, it is necessary that the nurse makes an early assessment of patients water needs to detect if there are signs of electrolyte imbalance. Dehydration can be a very serious problem, especially in children and the elderly. Dehydrations treatment with oral rehydration solution decreases the risk of developing hydration disorders, but even so, it is recommended to follow preventive measures to reduce the incidence and severity of dehydration. The key to having a proper hydration is prevention. Artificial nutrition encompasses the need for precise calculation of water needs in enteral nutrition as parenteral, so the nurse should be part of this process and use the tools for calculating the patient's requirements. All this helps to ensure an optimal nutritional status in patients at risk. Ethical dilemmas are becoming increasingly common in clinical practice. On the subject of artificial nutrition and hydration, there isn't yet any unanimous agreement regarding hydration as a basic care. It is necessary to take decisions in consensus with the health team, always thinking of the best interests of the patient.

  2. 羟基喜树碱/GA-PEI-PLGA纳米粒的制备及其工艺优化%Preparation and Optimization of Hydroxycamptothecin Loaded GA-PEI-PLGA Nanoparticles

    Institute of Scientific and Technical Information of China (English)

    梁劲康; 吴得天; 胡巧红; 吴雅琼

    2016-01-01

    目的:制备包载羟基喜树碱(HCPT)的甘草次酸修饰的 PEI-PLGA(GA-PEI-PLGA)纳米粒。方法采用超声乳化-减压溶剂挥发法制备 HCPT/ GA-PEI-PLGA 纳米粒。在单因素实验基础上,选取药物/载体比、油相/水相体积比、超声时间、超声功率为考察因素,以包封率和载药量为考察指标,通过正交设计实验对载药纳米粒的制备工艺进行优化,并对其粒径及 Zeta 电位进行测定。结果超声乳化-减压溶剂挥发法成功制得 HCPT/ GA-PEI-PLGA 纳米粒,其中药物/载体比对载药纳米粒制备的影响最大。优化后的处方工艺为:药物/载体比3:10、油相/水相体积比1:9、超声功率570 W、超声时间15 min。制得的载药纳米粒包封率高达(87.52±3.91)%,载药量为(20.10±4.72)%;平均粒径(218.1±3.23)nm,Zeta 电位为(34.98±3.56)mV。结论超声乳化-减压溶剂挥发法适于制备 HCPT/ GA-PEI-PLGA 纳米粒,制得的载药纳米粒包封率和载药量较高、粒径分布均匀、稳定性好。%Objective To prepare hydroxycamptothecin(HCPT)loaded glycyrrhetinic acid modified polyethyleneimine-poly(lactic-co-glycolic acid)( GA-PEI-PLGA)nanoparticles. Methods Emulsion-solvent evaporation method was used to prepare HCPT-loaded GA-PEI-PLGA nanoparticles. Based on the single-factor experiments,drug/ GA-PEI-PLGA ratio,oil phase/ water phase ratio,sonication timeand power were further investigated. The formulation and process were optimized by orthogonal testingdesign using entrapment efficiency and drug loading efficiency as indexes. HCPT-loaded GA-PEI-PLGA nanoparticles ˊ diameter and zeta potential were determined. Results HCPT-loaded GA-PEI-PLGA nanoparticles were successfully prepared by emulsion-solvent evaporation method.Drug/ GA-PEI-PLGA ratio,in particular,had the uniform particle on the preparation of HCPT-loaded nanoparticles.The optimal process was as follows:drug/ GA-PEI-PLGA ratio of

  3. Silica surfaces lubrication by hydrated cations adsorption from electrolyte solutions.

    Science.gov (United States)

    Donose, Bogdan C; Vakarelski, Ivan U; Higashitani, Ko

    2005-03-01

    Adsorption of hydrated cations on hydrophilic surfaces has been related to a variety of phenomena associated with the short-range interaction forces and mechanisms of the adhesive contact between the surfaces. Here we have investigated the effect of the adsorption of cations on the lateral interaction. Using lateral force microscopy (LFM), we have measured the friction force between a silica particle and silica wafer in pure water and in electrolyte solutions of LiCl, NaCl, and CsCl salts. A significant lubrication effect was demonstrated for solutions of high electrolyte concentrations. It was found that the adsorbed layers of smaller and more hydrated cations have a higher lubrication capacity than the layers of larger and less hydrated cations. Additionally, we have demonstrated a characteristic dependence of the friction force on the sliding velocity of surfaces. A mechanism for the observed phenomena based on the microstructures of the adsorbed layers is proposed.

  4. The effect of hydrate promoters on gas uptake.

    Science.gov (United States)

    Xu, Chun-Gang; Yu, Yi-Song; Ding, Ya-Long; Cai, Jing; Li, Xiao-Sen

    2017-08-16

    Gas hydrate technology is considered as a promising technology in the fields of gas storage and transportation, gas separation and purification, seawater desalination, and phase-change thermal energy storage. However, to date, the technology is still not commercially used mainly due to the low gas hydrate formation rate and the low gas uptake. In this study, the effect of hydrate promoters on gas uptake was systematically studied and analyzed based on hydrate-based CH4 storage and CO2 capture from CO2/H2 gas mixture experiments. Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR) and gas chromatography (GC) were employed to analyze the microstructures and gas compositions. The results indicate that the effect of the hydrate promoter on the gas uptake depends on the physical and chemical properties of the promoter and gas. A strong polar ionic promoter is not helpful towards obtaining the ideal gas uptake because a dense hydrate layer is easily formed at the gas-liquid interface, which hinders gas diffusion from the gas phase to the bulk solution. For a weak polar or non-polar promoter, the gas uptake depends on the dissolution characteristics among the different substances in the system. The lower the mutual solubility among the substances co-existing in the system, the higher the independence among the substances in the system; this is so that each phase has an equal chance to occupy the hydrate cages without or with small interactions, finally leading to a relatively high gas uptake.

  5. Computer simulation of alkali metal cation-montmorillonite hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Fang-Ru Chou [Columbia Univ., Palisades, NY (United States); Skipper, N.T. [Univ. College, London (United Kingdom); Sposito, G. [Lawrence Berkeley National Lab., CA (United States)

    1997-12-31

    Molecular structure in the interlayers of Li-, Na-, or K-Wyoming montmorillonite with one, two, or three adsorbed water layers was investigated for the first time by concurrent Monte Carlo and molecular dynamics (MD) simulation, based on the Matsouka-Clementi-Yoshimine, (MCY) model of water-water interactions. Calculated layer spacings, as well as interlayer-species self-diffusion coefficients, were in good agreement with available experimental data. Inner-sphere surface complexes of the cations with tetrahedral charge sites were observed for all hydrates, whereas outer-sphere surface complexes of the cations with octahedral charge sites, found also in the one-layer hydrate, tended to dissociate from the clay mineral basal planes into a diffuse layer in the two- and three-layer hydrates. Differences in the interlayer water structure among the hydrates mainly reflected cation solvation, although some water molecules were entrapped within cavities in the montmorillonite surface. All of the interlayer cation and water species exchanged on the time scale (0.2 ns) of the MD simulations. Comparisons with results obtained using, instead of the MCY model, the TIP4P model for water-water, cation-water, and cation-clay interactions indicated that layer spacings and interlayer species mobilities tend to be under-predicted by the TIP4P model.

  6. Preparation of PEI/PVA Superfine Fiber Loaded with Nano-Rhodium Hybrid Material by Electrospinning Technique%静电纺丝制备PEI/PVA超细纤维负载纳米铑杂化材料的研究

    Institute of Scientific and Technical Information of China (English)

    蔡盛赢; 蔡颖婷; 朱罕; 王盼; 包世勇; 邹美玲; 杜明亮; 张明

    2013-01-01

    利用NaBH4作为还原剂,表没食子儿茶素没食子酸酯(EGCG)为稳定剂,还原RhCl3水溶液制备铑纳米颗粒,并用透射电镜(TEM)研究了铑纳米颗粒的形貌.通过静电纺丝技术制备了PEI/PVA纳米纤维,并用戊二醛作为交联剂使之交联以提高其耐水性.然后在交联过的PEI/PVA纤维膜上负载铑纳米颗粒;利用傅里叶红外光谱仪(FTIR)、扫描电子显微镜(SEM)对PEI/PVA以及Rh/PEI/PVA薄膜进行了表征.结果表明:利用静电纺丝技术和复合技术可以制备PEI/PVA超细纤维负载纳米铑的杂化材料.

  7. Studies on Heteroses of Pei'ai 64S/Javanica Rice

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Agronomic traits and heteroses of javanica varieties and the indica/javanica hybrids in Changsha are reported. Javanica rice exhibits long panicles, big grains, less panicles per plant, a long growth duration and high plant height in Changsha. The hybrid of Pei'ai 64S/javanica possesses positive heterobeltiosis in culm height, panicle length, panicles per plant, spikelets per panicle, grains per panicle, yield per plant, theoretic yield per hectare and actual yield per hectare; performs negative heterobeltiosis in days to flower, seed setting rate and 1000-grain weight. There are significant linear regression relations between culm height of the hybrid and panicle length of its male parent, panicle length of the hybrid and that of its male parent, spikelets per panicle of the hybrid and spikelets per panicle and panicle length of its male parent, grains per panicle of the hybrid and spikelets per panicle of its male parent, 1000-grain weight of the hybrid and spikelets per panicle of its male parent, respectively. In general, significant differences at 1% level are seen in most traits except grains per panicle and theoretic yield per hectare between the indica/javanica hybrid and Pei'ai 64S/Teqin (CK). Compared with the check, the indica/javanica hybrids have positive standard heterosis in culm height, panicle length, spikelets per panicle, grains per panicle and 1000-grain weight but negative standard heterosis in days to flower, panicles per plant, seed setting rate, theoretic yield per hectare and actual yield per hectare. For the individuals, 11.1% hybrids possess > 40% standard heterosis in theoretic yield per hectare, 3.7% possess >40% standard heterosis in actual yield per hectare. The javanica restorer line 770 derives from a single cross of Pei'ai 64S/Moroberekan B-51-4-9-2. The hybrid 43S/770 possesses an elite plant type and strong heterosis.

  8. Research on SF/PEI self-assembly nano fiber membrane for filtering Cu2+%SF/PEI自组装纳米纤维膜用于Cu2+过滤的研究

    Institute of Scientific and Technical Information of China (English)

    马瑞丽; 何建新; 张弦

    2012-01-01

    采用静电层层自组装技术将丝素(SF)与聚乙烯亚胺(PEI)复合制备的SF/PEI纳米纤维,随着自组装层数的增多,纤维直径变粗,表面变得不规整,且在一定的自组装层数内,复合纳米纤维膜对Cu2+的过滤效率不断增大.杂化Fe后,纤维表面变得更加凹凸不平,但对Cu2+的过滤效果显著改善.这对于制备新型、高效、无二次污染、低治理成本的替代或改进的重金属过滤材料提供了理论意义.%F/PEI composite Nano fiber membrane was made in this experiment by layer-layer electrostatic self-assembly technology, With the increasing in the number in self-assembly layer, the fiber diameter become larger, the surface become irregular, and in certain layer, the adsorption efficiency of Cu2+ increases. After the hybrid Fe, fiber surface become more uneven, but the adsorption efficiency improved significantly. This experiment provides theoretical significance for new, effective, no secondary pollution and low management cost alternative or improved heavy metal filter material.

  9. Clinical study on orofacial photonic hydration using phototherapy and biomaterials

    Science.gov (United States)

    Lizarelli, Rosane F. Z.; Grandi, Natália D. P.; Florez, Fernando L. E.; Grecco, Clovis; Lopes, Luciana A.

    2015-06-01

    Skin hydration is important to prevent aging and dysfunction of orofacial system. Nowadays, it is known that cutaneous system is linked to muscle system, then every dentist need to treat healthy facial skin, as lips, keeping orofacial functions healthy. Thirty-two patients were treated using laser and led therapy single or associated to biomaterials (dermo-cosmetics) searching for the best protocol to promote skin hydration. Using a peace of equipment to measure electric impedance, percentage of water and oil from skin, before and after different treatments were analyzed. Statistic tests using 5% and 0.1% of significance were applied and results showed that light could improve hydration of epidermis layer of facial skin. Considering just light effect, using infrared laser followed by blue led system is more effective to hydration than just blue led system application. Considering dermo-cosmetic and light, the association between both presented the best result.

  10. Advances in understanding hydration of Portland cement

    Energy Technology Data Exchange (ETDEWEB)

    Scrivener, Karen L., E-mail: Karen.scrivener@epfl.ch [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, 1015 (Switzerland); Juilland, Patrick [Sika Technology AG, Zürich (Switzerland); Monteiro, Paulo J.M. [Department of Civil and Environmental Engineering, University of California at Berkeley (United States)

    2015-12-15

    Progress in understanding hydration is summarized. Evidence supports the geochemistry dissolution theory as an explanation for the induction period, in preference to the inhibiting layer theory. The growth of C–S–H is the principal factor controlling the main heat evolution peak. Electron microscopy indicates that C–S–H “needles” grow from the surface of grains. At the peak, the surface is covered, but deceleration cannot be attributed to diffusion control. The shoulder peak comes from renewed reaction of C{sub 3}A after depletion of sulfate in solution, but release of sulfate absorbed on C–S–H means that ettringite continues to form. After several days space becomes the major factor controlling hydration. The use of new analytical technique is improving our knowledge of the action of superplasticizers and leading to the design of molecules for different applications. Atomistic modeling is becoming a topic of increasing interest. Recent publications in this area are reviewed.

  11. Hyaluronic acid reagent functional chitosan-PEI conjugate with AQP2-siRNA suppressed endometriotic lesion formation

    Directory of Open Access Journals (Sweden)

    Zhao MD

    2016-03-01

    Full Text Available Meng-Dan Zhao,1 Jin-Lin Cheng,2 Jing-Jing Yan,1 Feng-Ying Chen,1 Jian-Zhong Sheng,3 Dong-Li Sun,1 Jian Chen,4 Jing Miao,4 Run-Ju Zhang,1 Cai-Hong Zheng,1 He-Feng Huang1,5 1Women’s Hospital, School of Medicine, Zhejiang University, Hangzhou, 2State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, 3Department of Pathophysiology, School of Medicine, 4The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, 5International Peace Maternity and Child Health Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, People’s Republic of China Abstract: To identify a new drug candidate for treating endometriosis which has fewer side effects, a new polymeric nanoparticle gene delivery system consisting of polyethylenimine-grafted chitosan oligosaccharide (CSO-PEI with hyaluronic acid (HA and small interfering RNA (siRNA was designed. There was no obvious difference in sizes observed between (CSO-PEI/siRNAHA and CSO-PEI/siRNA, but the fluorescence accumulation in the endometriotic lesion was more significant for (CSO-PEI/siRNAHA compared with CSO-PEI/siRNA due to the specific binding of HA to CD44. In addition, the (CSO-PEI/siRNAHA nanoparticle gene therapy significantly decreased the endometriotic lesion sizes with atrophy and degeneration of the ectopic endometrium. The epithelial cells of ectopic endometrium from rat models of endometriosis showed a significantly lower CD44 expression than control after treatment with (CSO-PEI/siRNAHA. Furthermore, observation under an electron microscope showed no obvious toxic effect on the reproductive organs. Therefore, (CSO-PEI/siRNAHA gene delivery system can be used as an effective method for the treatment of endometriosis. Keywords: chitosan-PEI, hyaluronic acid, AQP2-siRNA, endometriosis, targeted therapy 

  12. Modeling Hydrates and the Gas Hydrate Markup Language

    Directory of Open Access Journals (Sweden)

    Weihua Wang

    2007-06-01

    Full Text Available Natural gas hydrates, as an important potential fuels, flow assurance hazards, and possible factors initiating the submarine geo-hazard and global climate change, have attracted the interest of scientists all over the world. After two centuries of hydrate research, a great amount of scientific data on gas hydrates has been accumulated. Therefore the means to manage, share, and exchange these data have become an urgent task. At present, metadata (Markup Language is recognized as one of the most efficient ways to facilitate data management, storage, integration, exchange, discovery and retrieval. Therefore the CODATA Gas Hydrate Data Task Group proposed and specified Gas Hydrate Markup Language (GHML as an extensible conceptual metadata model to characterize the features of data on gas hydrate. This article introduces the details of modeling portion of GHML.

  13. Overview: Nucleation of clathrate hydrates

    Science.gov (United States)

    Warrier, Pramod; Khan, M. Naveed; Srivastava, Vishal; Maupin, C. Mark; Koh, Carolyn A.

    2016-12-01

    Molecular level knowledge of nucleation and growth of clathrate hydrates is of importance for advancing fundamental understanding on the nature of water and hydrophobic hydrate formers, and their interactions that result in the formation of ice-like solids at temperatures higher than the ice-point. The stochastic nature and the inability to probe the small length and time scales associated with the nucleation process make it very difficult to experimentally determine the molecular level changes that lead to the nucleation event. Conversely, for this reason, there have been increasing efforts to obtain this information using molecular simulations. Accurate knowledge of how and when hydrate structures nucleate will be tremendously beneficial for the development of sustainable hydrate management strategies in oil and gas flowlines, as well as for their application in energy storage and recovery, gas separation, carbon sequestration, seawater desalination, and refrigeration. This article reviews various aspects of hydrate nucleation. First, properties of supercooled water and ice nucleation are reviewed briefly due to their apparent similarity to hydrates. Hydrate nucleation is then reviewed starting from macroscopic observations as obtained from experiments in laboratories and operations in industries, followed by various hydrate nucleation hypotheses and hydrate nucleation driving force calculations based on the classical nucleation theory. Finally, molecular simulations on hydrate nucleation are discussed in detail followed by potential future research directions.

  14. A study on gas hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Byoung Jae; Jung, Tae Jin; Sunwoo, Don [Korea Institute of Geology Mining and Materials, Taejon (Korea, Republic of)

    1996-12-01

    Sufficient documents were reviewed to understand solid components of water and gaseous hydrocarbon known as gas hydrates, which represent an important potential energy resource of the future. The review provides us with valuable information on crystal structures, kinetics, origin and distribution of gas hydrates. In addition, the review increased our knowledge of exploration and development methods of gas hydrates. Large amounts of methane, the principal component of natural gas, in the form of solid gas hydrate are found mainly offshore in outer continental margin sediment and, to a lesser extent, in polar regions commonly associated with permafrost. Natural gas hydrates are stable in some environments where the hydrostatic pressure exerted by overlying water column is sufficient for hydrate formation and stability. The required high pressures generally restrict gas hydrate to sediments beneath water of approximately 400 m. Higher sediment temperatures at greater subbottom depths destabilize gas hydrates. Based on the pressure- temperature condition, the outer continental margin of East Sea where water depth is deep enough to form gas hydrate is considered to have high potential of gas hydrate accumulations. (author). 56 refs., tabs., figs.

  15. Enhanced Delivery of Plasmid Encoding Interleukin-12 Gene by Diethylene Triamine Penta-Acetic Acid (DTPA)-Conjugated PEI Nanoparticles.

    Science.gov (United States)

    Dehshahri, Ali; Sadeghpour, Hossein; Keykhaee, Maryam; Khalvati, Bahman; Sheikhsaran, Fatemeh

    2016-05-01

    Recombinant therapeutic proteins have been considered as an efficient category of medications used for the treatment of various diseases. Despite their effectiveness, there are some reports on the systemic adverse effects of recombinant therapeutic proteins limiting their wide clinical applications. Among different cytokines used for cancer immunotherapy, interleukin-12 (IL-12) has shown great ability as a powerful antitumor and antiangiogenic agent. However, significant toxic reactions following the systemic administration of IL-12 have led researchers to seek for alternative approaches such as the delivery and local expression of the IL-12 gene inside the tumor tissues. In order to transfer the plasmid encoding IL-12 gene, the most extensively investigated polycationic polymer, polyethylenimine (PEI), was modified by diethylene triamine penta-acetic acid (DTPA) to modulate the hydrophobic-hydrophilic balance of the polymer as well as its toxicity. DTPA-conjugated PEI derivatives were able to form complexes in the size range around 100-180 nm with great condensation ability and protection of the plasmid against enzymatic degradation. The highest gene transfer ability was achieved by the DTPA-conjugated PEI at the conjugation degree of 0.1 % where the level of IL-12 production increased up to twofold compared with that of the unmodified PEI. Results of the present study demonstrated that modulation of the surface positive charge of PEI along with the improvement of the polymer hydrophobic balance could be considered as a successful strategy to develop safe and powerful nanocarriers.

  16. Enhanced CO2 adsorptive performance of PEI/SBA-15 adsorbent using phosphate ester based surfactants as additives.

    Science.gov (United States)

    Cheng, Dandan; Liu, Yue; Wang, Haiqiang; Weng, Xiaole; Wu, Zhongbiao

    2015-12-01

    In this study, a series of polyetherimide/SBA-15: 2-D hexagonal P6mm, Santa Barbara USA (PEI/SBA-15) adsorbents modified by phosphoric ester based surfactants (including tri(2-ethylhexyl) phosphate (TEP), bis(2-ethylhexyl) phosphate (BEP) and trimethyl phosphonoacetate (TMPA)) were prepared for CO2 adsorption. Experimental results indicated that the addition of TEP and BEP had positive effects on CO2 adsorption capacity over PEI/SBA-15. In particular, the CO2 adsorption amount could be improved by around 20% for 45PEI-5TEP/SBA-15 compared to the additive-free adsorbent. This could be attributed to the decrease of CO2 diffusion resistance in the PEI bulk network due to the interactions between TEP and loaded PEI molecules, which was further confirmed by adsorption kinetics results. In addition, it was also found that the cyclic performance of the TEP-modified adsorbent was better than the surfactant-free one. This could be due to two main reasons, based on the results of in situ DRIFT and TG-DSC tests. First and more importantly, adsorbed CO2 species could be desorbed more rapidly over TEP-modified adsorbent during the thermal desorption process. Furthermore, the enhanced thermal stability after TEP addition ensured lower degradation of amine groups during adsorption/desorption cycles.

  17. Novel PEI/Poly-γ-Gutamic Acid Nanoparticles for High Efficient siRNA and Plasmid DNA Co-Delivery

    Directory of Open Access Journals (Sweden)

    Shu-Fen Peng

    2017-01-01

    Full Text Available The efficient delivery of sufficient amounts of nucleic acids into target cells is critical for successful gene therapy and gene knockdown. The DNA/siRNA co-delivery system has been considered a promising approach for cancer therapy to simultaneously express and inhibit tumor suppressor genes and overexpressed oncogenes, respectively, triggering synergistic anti-cancer effects. Polyethylenimine (PEI has been identified as an efficient non-viral vector for transgene expression. In this study, we created a very high efficient DNA/siRNA co-delivery system by incorporating a negatively-charged poly-γ-glutamic acid (γ-PGA into PEI/nucleic acid complexes. Spherical nanoparticles with about 200 nm diameter were formed by mixing PEI/plasmid DNA/siRNA/γ-PGA (dual delivery nanoparticles; DDNPs with specific ratio (N/P/C ratio and the particles present positive surface charge under all manufacturing conditions. The gel retardation assay shows both nucleic acids were effectively condensed by PEI, even at low N/P ratios. The PEI-based DDNPs reveal excellent DNA/siRNA transfection efficiency in the human hepatoma cell line (Hep 3B by simultaneously providing high transgene expression efficiency and high siRNA silencing effect. The results indicated that DDNP can be an effective tool for gene therapy against hepatoma.

  18. Novel PEI/Poly-γ-Gutamic Acid Nanoparticles for High Efficient siRNA and Plasmid DNA Co-Delivery.

    Science.gov (United States)

    Peng, Shu-Fen; Hsu, Hung-Kun; Lin, Chun-Cheng; Cheng, Ya-Ming; Hsu, Kuang-Hsing

    2017-01-04

    The efficient delivery of sufficient amounts of nucleic acids into target cells is critical for successful gene therapy and gene knockdown. The DNA/siRNA co-delivery system has been considered a promising approach for cancer therapy to simultaneously express and inhibit tumor suppressor genes and overexpressed oncogenes, respectively, triggering synergistic anti-cancer effects. Polyethylenimine (PEI) has been identified as an efficient non-viral vector for transgene expression. In this study, we created a very high efficient DNA/siRNA co-delivery system by incorporating a negatively-charged poly-γ-glutamic acid (γ-PGA) into PEI/nucleic acid complexes. Spherical nanoparticles with about 200 nm diameter were formed by mixing PEI/plasmid DNA/siRNA/γ-PGA (dual delivery nanoparticles; DDNPs) with specific ratio (N/P/C ratio) and the particles present positive surface charge under all manufacturing conditions. The gel retardation assay shows both nucleic acids were effectively condensed by PEI, even at low N/P ratios. The PEI-based DDNPs reveal excellent DNA/siRNA transfection efficiency in the human hepatoma cell line (Hep 3B) by simultaneously providing high transgene expression efficiency and high siRNA silencing effect. The results indicated that DDNP can be an effective tool for gene therapy against hepatoma.

  19. Drilling Gas Hydrates on hydrate Ridge, Oregon continental margin

    Science.gov (United States)

    Trehu, A. M.; Bohrmann, G.; Leg 204 Science Party

    2002-12-01

    During Leg 204, we cored and logged 9 sites on the Oregon continental margin to determine the distribution and concentration of gas hydrates in an accretionary ridge and adjacent slope basin, investigate the mechanisms that transport methane and other gases into the gas hydrate stability zone (GHSZ), and obtain constraints on physical properties of hydrates in situ. A 3D seismic survey conducted in 2000 provided images of potential subsurface fluid conduits and indicated the position of the GHSZ throughout the survey region. After coring the first site, we acquired Logging-While-Drilling (LWD) data at all but one site to provide an overview of downhole physical properties. The LWD data confirmed the general position of key seismic stratigraphic horizons and yielded an initial estimate of hydrate concentration through the proxy of in situ electrical resistivity. These records proved to be of great value in planning subsequent coring. The second new hydrate proxy to be tested was infrared thermal imaging of cores on the catwalk as rapidly as possible after retrieval. The thermal images were used to identify hydrate samples and to estimate the distribution and texture of hydrate within the cores. Geochemical analyses of interstitial waters and of headspace and void gases provide additional information on the distribution and concentration of hydrate within the stability zone, the origin and pathway of fluids into and through the GHSZ, and the rates at which gas hydrate is forming. Bio- and lithostratigraphic description of cores, measurement of physical properties, and in situ pressure core sampling and thermal measurements complement the data set, providing ground-truth tests of inferred physical and sedimentological properties. Among the most interesting preliminary results are: 1) that gas hydrates are distributed through a broad depth range within the GHSZ and that different physical and chemical proxies for hydrate distribution and concentration give generally

  20. Layer-by-layer assembly of nanocomposite films with thickness up to hundreds of nanometers

    Institute of Scientific and Technical Information of China (English)

    ZHOU Ling-de; YAN Yu-hua; YU Hai-hu; GU Er-dan; JIANG De-sheng

    2006-01-01

    Polyelectrolyte/polyelectrolyte, organic molecule/colloidal CdS and polyelectrolyte/MWCNT films were fabricated via the layer-by-layer assembling technique. The assembled films were characterized by UV-vis spectrophotometer, X-ray diffractometry,nano profilometer and scanning electron microscopy. The results demonstrate that the layer-by-layer assembling technique can be used to make the nanoscaled films from polyelectrolytes and thicker composite films from suitable precursor materials. Both organic molecule/colloidal CdS films and PEI/MWCNT films with thickness of hundreds of nanometers were obtained. For the organic molecule/colloidal CdS films, a reasonable explanation for the result is that both the organic molecules and the CdS particles aggregate in the films. For the PEI/MWCNT films, obviously, it is the MWCNT that makes the great contribution to the film thickness.

  1. PEI Domestic Oil Tank Program : a history of recent oil spills on Prince Edward Island

    Energy Technology Data Exchange (ETDEWEB)

    McInnis, D.

    2001-04-01

    This power point presentation addressed the issue of recent oil spills on Prince Edward Island (PEI) with a critical examination of the Home Heat Tank Program in the province and how insurance companies, banks and real estate industry are dealing with the problem of oil spill contamination. The number of above ground domestic home heating tank spills continues to remain high and have been increasing in the past 10 years. This is due in part to improper installations which are essentially putting the safety of many homeowners and the environment at risk. It was noted that in Prince Edward Island, home heat tank installations do not have to be performed by qualified persons. Therefore, in order to save money, many home owners cut corners. Most improper installations are attributed to people who are not aware of proper guidelines and do not follow proper requirements and guidelines. In 1999 there were 208 domestic oil spills reported in PEI, of which 125 involved 17 tons or less of contaminated soil, 62 involved 51 tons of contaminated soil and 21 involved 51 tons or more of contaminated soil. The cost of cleanup for the latter was in the tens of thousands of dollars. It was recommended that this problem should be addressed in a 4 phase approach involving stakeholder consultation, public education, program assessment and regulation amendments. 37 figs.

  2. Combination of adenovirus and cross-linked low molecular weight PEI improves efficiency of gene transduction

    Energy Technology Data Exchange (ETDEWEB)

    Han Jianfeng; Zhao Dong; Zhong Zhirong; Zhang Zhirong; Gong Tao; Sun Xun, E-mail: xunsun22@gmail.com [Key Laboratory of Drug Targeting and Novel Drug Delivery Systems, Ministry of Education, West China School of Pharmacy, Sichuan University, Chengdu, Sichuan, 610041 (China)

    2010-03-12

    Recombinant adenovirus (Ad)-mediated gene therapy is an exciting novel strategy in cancer treatment. However, poor infection efficiency with coxsackievirus and adenovirus receptor (CAR) down-regulated cancer cell lines is one of the major challenges for its practical and extensive application. As an alternative method of viral gene delivery, a non-viral carrier using cationic materials could compensate for the limitation of adenovirus. In our study, adenovectors were complexed with a new synthetic polymer PEI-DEG-bis-NPC (PDN) based on polyethylenimine (PEI), and then the properties of the vehicle were characterized by measurement of size distribution, zeta potential and transmission electron microscopy (TEM). Enhancement of gene transduction by Ad/PDN complexes was observed in both CAR-overexpressing cell lines (A549) and CAR-lacking cell lines (MDCK, CHO, LLC), as a result of facilitating binding and cell uptake of adenoviral particles by the cationic component. Ad/PDN complexes also promoted the inhibition of tumor growth in vivo and prolonged the survival time of tumor-bearing mice. These data suggest that a combination of viral and non-viral gene delivery methods may offer a new approach to successful cancer gene therapy.

  3. Use of PEI-coated Magnetic Iron Oxide Nanoparticles as Gene Vectors

    Institute of Scientific and Technical Information of China (English)

    韦卫中; 徐春芳; 吴华

    2004-01-01

    To evaluate the feasibility of using polyethyleneimine (PEI) coated magnetic iron oxide nanoparticles (polyMAG-1000) as gene vectors. The surface characteristics of the nanoparticles were observed with scanning electron microscopy. The ability of the nanoparticles to combine with and protect DNA was investigated at different PH values after polyMAG-1000 and DNA were combined in different ratios. The nanoparticles were tested as gene vectors with in vitro transfection models. Under the scanning electron microscope the nanoparticles were about 100 nm in diameter.The nanoparticles could bind and condense DNA under acid, neutral and alkaline conditions, and they could transfer genes into cells and express green fluorescent proteins (GFP). The transfection efficiency was highest (51 %) when the ratio of nanoparticles to DNA was 1:1 (v:w). In that ratio, the difference in transfection efficiency was marked depending on whether a magnetic field was present or not: about 10 % when it was absent but 51 % when it was present. The magnetic iron oxide nanoparticles coated with PEI may potentially be used as gene vectors.

  4. Rapid gas hydrate formation process

    Science.gov (United States)

    Brown, Thomas D.; Taylor, Charles E.; Unione, Alfred J.

    2013-01-15

    The disclosure provides a method and apparatus for forming gas hydrates from a two-phase mixture of water and a hydrate forming gas. The two-phase mixture is created in a mixing zone which may be wholly included within the body of a spray nozzle. The two-phase mixture is subsequently sprayed into a reaction zone, where the reaction zone is under pressure and temperature conditions suitable for formation of the gas hydrate. The reaction zone pressure is less than the mixing zone pressure so that expansion of the hydrate-forming gas in the mixture provides a degree of cooling by the Joule-Thompson effect and provides more intimate mixing between the water and the hydrate-forming gas. The result of the process is the formation of gas hydrates continuously and with a greatly reduced induction time. An apparatus for conduct of the method is further provided.

  5. Utilization of PEI-modified Corynebacterium glutamicum biomass for the recovery of Pd(II) in hydrochloric solution.

    Science.gov (United States)

    Won, Sung Wook; Park, Jiyeong; Mao, Juan; Yun, Yeoung-Sang

    2011-02-01

    A new type of biosorbent was developed for binding anionic precious metals through cross-linking waste biomass Corynebacterium glutamicum with polyethylenimine (PEI). This biomass was evaluated for the removal and recovery of palladium and compared to commercial adsorbents, such as Amberjet 4200 Cl, Lewatit Monoplus TP 214, SPC-100, and SPS-200. The kinetic experiments revealed that the sorption equilibrium was reached with 30 min for the PEI-modified biomass. The maximum uptake of the biosorbent was 176.8 mg/g, which was calculated using the Langmuir model. The Pd(II) maximum uptake exhibited the following order: Amberjet 4200 Cl>Lewatit Monoplus TP 214>PEI-modified biomass>SPC-100>SPS-200. Acidified thiourea in 1.0M HCl was used to desorb Pd(II) from all of the sorbents examined.

  6. Targeted delivery of Bcl-2 conversion gene by MPEG-PCL-PEI-FA cationic copolymer to combat therapeutic resistant cancer.

    Science.gov (United States)

    Li, Zibiao; Liu, Xuan; Chen, Xiaohong; Chua, Ming Xuan; Wu, Yun-Long

    2017-07-01

    Deregulation of anti-apoptosis Bcl-2 protein expression was a key feature in human cancers with therapeutic resistance. Nuclear receptor Nur77 could induce the conformation change of Bcl-2 protein and converted it into an apoptosis inducer by "enemy to friend" strategy. However, the safe and effective delivery of this gene to combat therapeutic resistant cancer remained largely unexplored. In this report, we designed an amphiphilic cationic MPEG-PCL-PEI-FA copolymer, comprising biocompatible and hydrophilic methoxy-poly(ethylene glycol) (MPEG), biodegradable and hydrophobic poly(ε-caprolactone) (PCL), cationic poly(ethylene imine) (PEI) segments, and folic acid (FA) as targeting group, as a high efficient Nur77 gene carrier to folate receptor (FR) highly expressed and therapeutic resistant HeLa/Bcl-2 cancer cells. Interestingly, due to the incorporation of PCL and PEG segments, this MPEG-PCL-PEI-FA copolymer showed less toxicity but better gene transfection efficiency than non-viral gene carrier gold standard PEI (25kDa). This might be due to the formation of micelles to stabilize polyplex for enhanced gene transfection ability. More importantly, MPEG-PCL-PEI-FA copolymer exhibited excellent growth inhibition ability on therapeutic resistant HeLa/Bcl-2 cancer cells, which was FR overexpressed HeLa cervical cancer cells with high expression of Bcl-2 protein, thanks to its FA induced targeting ability, high gene transfection efficiency, and low cytotoxicity. This work signifies the first time that cationic amphiphilic MPEG-PCL-PEI-FA copolymers could be utilized for the gene delivery to therapeutic resistant cancer cells with high expression of anti-apoptosis Bcl-2 protein and the positive results are encouraging for the further design of polymeric platforms for combating drug resistant tumors. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Maltose- and maltotriose-modified, hyperbranched poly(ethylene imine)s (OM-PEIs): Physicochemical and biological properties of DNA and siRNA complexes.

    Science.gov (United States)

    Höbel, Sabrina; Loos, Andrea; Appelhans, Dietmar; Schwarz, Simona; Seidel, Jürgen; Voit, Brigitte; Aigner, Achim

    2011-01-20

    Polycationic non-viral polymers are widely employed as delivery platforms of plasmid DNA, or of small interfering RNAs (siRNAs) for the induction of RNA interference (RNAi). Among those, poly(ethylene imine)s (PEIs) take a prominent position due to their relatively high efficacy; however, their biodistribution profiles upon systemic delivery and their toxicity pose limitations which can be addressed by the introduction of PEI modifications. In this paper, we systematically analyse physicochemical and biological properties of DNA and siRNA complexes prepared from a set of maltose-, maltotriose- or maltoheptaose-modified hyperbranched PEIs (termed (oligo-)maltose-modified PEIs; OM-PEIs). We show that pH-dependent charge densities of the OM-PEIs correlate with the structure and degree of grafting, and the length of the oligomaltose. Decreased zeta potentials of OM-PEI-based complexes and changes in the thermodynamics of DNA complex formation are observed, while the complex sizes are largely unaffected by maltose grafting and the presence of serum proteins. Furthermore, although complexation efficacies of siRNAs are not altered, complex stabilities are markedly increased in OM-PEI complexes. DNA complex uptake and transfection kinetics are slowed down upon maltose-grafting of the PEI which can be attributed to decreased zeta potentials, and alterations in the uptake mechanisms (clathrin-dependent/clathrin-independent endocytosis) are observed. Independent of the maltose architecture, DNA and siRNA complexes based on maltose-grafted PEI show considerably lower cytotoxicity as compared to PEI complexes. While maltose grafting generally leads to reduced in vitro transfection efficacies, this effect is less profound in some OM-PEI/siRNA complexes as compared to OM-PEI/DNA complexes. Importantly, upon their systemic application in vivo, OM-PEI/siRNA complexes show marked differences in the siRNA biodistribution profile with e.g. substantially decreased siRNA levels in the

  8. The PEI-introduced CS shell/PMMA core nanoparticle for silencing the expression of E6/E7 oncogenes in human cervical cells.

    Science.gov (United States)

    Saengkrit, Nattika; Sanitrum, Phakorn; Woramongkolchai, Noppawan; Saesoo, Somsak; Pimpha, Nuttaporn; Chaleawlert-Umpon, Saowaluk; Tencomnao, Tewin; Puttipipatkhachorn, Satit

    2012-10-15

    In this study, we examined the potential of cationic nanoparticle - polyethyleneimine-introduced chitosan shell/poly (methyl methacrylate) core nanoparticles (CS-PEI) for siRNA delivery. Initially, DNA delivery was performed to validate the capability of CS-PEI for gene delivery in the human cervical cancer cell line, SiHa. siRNA delivery were subsequently carried out to evaluate the silencing effect on targeted E6 and E7 oncogenes. Physicochemical properties including size, zeta potential and morphology of CS-PEI/DNA and CS-PEI/siRNA complexes, were analyzed. The surface charges and sizes of the complexes were observed at different N/P ratios. The hydrodynamic sizes of the CS-PEI/DNA and CS-PEI/siRNA were approximately 300-400 and 400-500nm, respectively. Complexes were positively charged depending on the amount of added CS-PEI. AFM images revealed the mono-dispersed and spherical shapes of the complexes. Gel retardation assay confirmed that CS-PEI nanoparticles completely formed complexes with DNA and siRNA at a N/P ratio of 1.6. For DNA transfection, CS-PEI provided the highest transfection result. Localization of siRNA delivered through CS-PEI was confirmed by differential interference contrast (DIC) confocal imaging. The silencing effect of siRNA specific to HPV 16 E6/E7 oncogene was examined at 18 and 24h post-transfection. The results demonstrated the capacity of CS-PEI to suppress the expression of HVP oncogenes. Copyright © 2012 Elsevier Ltd. All rights reserved.

  9. Aminopolymer Mobility and Support Interactions in Silica-PEI Composites for CO2 Capture Applications: A Quasielastic Neutron Scattering Study.

    Science.gov (United States)

    Holewinski, Adam; Sakwa-Novak, Miles A; Carrillo, Jan-Michael Y; Potter, Matthew E; Ellebracht, Nathan; Rother, Gernot; Sumpter, Bobby G; Jones, Christopher W

    2017-07-13

    Composite gas sorbents, formed from an active polymer phase and a porous support, are promising materials for the separation of acid gases from a variety of gas streams. Significant changes in sorption performance (capacity, rate, stability etc.) can be achieved by tuning the properties of the polymer and the nature of interactions between polymer and support. Here we utilize quasielastic neutron scattering (QENS) and coarse-grained molecular dynamics (MD) simulations to characterize the dynamic behavior of the most commonly reported polymer in such materials, poly(ethylenimine) (PEI), both in bulk form and when supported in a mesoporous silica framework. The polymer chain dynamics (rotational and translational diffusion) are characterized using two neutron backscattering spectrometers that have overlapping time scales, ranging from picoseconds to a few nanoseconds. Two modes of motion are detected for the PEI molecule in QENS. At low energy transfers, a "slow process" on the time scale of ∼200 ps is found and attributed to jump-mediated, center-of-mass diffusion. A second, "fast process" at ∼20 ps scale is also found and is attributed to a locally confined, jump-diffusion. Characteristic data (time scale and spectral weight) of these processes are compared to those characterized by MD, and reasonable agreement is found. For the nanopore-confined PEI, we observe a significant reduction in the time scale of polymer motion as compared to the bulk. The impacts of silica surface functionalization and of polymer fill fraction in the silica pores (controlling the portion of polymer molecules in contact with the pore walls), are both studied in detail. Hydrophobic functionalization of the silica leads to an increase of the PEI mobility above that in native silanol-terminated silica, but the dynamics are still slower than those in bulk PEI. Sorbents with faster PEI dynamics are also found to be more efficient for CO2 capture, possibly because sorption sites are more

  10. Seepage from an arctic shallow marine gas hydrate reservoir is insensitive to momentary ocean warming

    Science.gov (United States)

    Hong, Wei-Li; Torres, Marta E.; Carroll, Jolynn; Crémière, Antoine; Panieri, Giuliana; Yao, Haoyi; Serov, Pavel

    2017-06-01

    Arctic gas hydrate reservoirs located in shallow water and proximal to the sediment-water interface are thought to be sensitive to bottom water warming that may trigger gas hydrate dissociation and the release of methane. Here, we evaluate bottom water temperature as a potential driver for hydrate dissociation and methane release from a recently discovered, gas-hydrate-bearing system south of Spitsbergen (Storfjordrenna, ~380 m water depth). Modelling of the non-steady-state porewater profiles and observations of distinct layers of methane-derived authigenic carbonate nodules in the sediments indicate centurial to millennial methane emissions in the region. Results of temperature modelling suggest limited impact of short-term warming on gas hydrates deeper than a few metres in the sediments. We conclude that the ongoing and past methane emission episodes at the investigated sites are likely due to the episodic ventilation of deep reservoirs rather than warming-induced gas hydrate dissociation in this shallow water seep site.

  11. Nonequilibrium adiabatic molecular dynamics simulations of methane clathrate hydrate decomposition

    Science.gov (United States)

    Alavi, Saman; Ripmeester, J. A.

    2010-04-01

    Nonequilibrium, constant energy, constant volume (NVE) molecular dynamics simulations are used to study the decomposition of methane clathrate hydrate in contact with water. Under adiabatic conditions, the rate of methane clathrate decomposition is affected by heat and mass transfer arising from the breakup of the clathrate hydrate framework and release of the methane gas at the solid-liquid interface and diffusion of methane through water. We observe that temperature gradients are established between the clathrate and solution phases as a result of the endothermic clathrate decomposition process and this factor must be considered when modeling the decomposition process. Additionally we observe that clathrate decomposition does not occur gradually with breakup of individual cages, but rather in a concerted fashion with rows of structure I cages parallel to the interface decomposing simultaneously. Due to the concerted breakup of layers of the hydrate, large amounts of methane gas are released near the surface which can form bubbles that will greatly affect the rate of mass transfer near the surface of the clathrate phase. The effects of these phenomena on the rate of methane hydrate decomposition are determined and implications on hydrate dissociation in natural methane hydrate reservoirs are discussed.

  12. Numerical simulations of sand production in interbedded hydrate-bearing sediments during depressurization

    Science.gov (United States)

    Uchida, Shun; Lin, Jeen-Shang; Myshakin, Evgeniy; Seol, Yongkoo; Collett, Timothy S.; Boswell, Ray

    2017-01-01

    Geomechanical behavior of hydrate-bearing sediments during gas production is complex, involving changes in hydrate-dependent mechanical properties. When interbedded clay layers are present, the complexity is more pronounced because hydrate dissociation tends to occur preferentially in the sediments adjacent to the clay layers due to clay layers acting as a heat source. This would potentially lead to shearing deformation along the sand/clay contacts and may contribute to solid migration, which hindered past field-scale gas production tests. This paper presents a near-wellbore simulation of sand/clay interbedded hydrate-bearing sediments that have been subjected to depressurization and discusses the effect of clay layers on sand production.

  13. Layer-by-layer assembled TiO{sub 2} films with high ultraviolet light-shielding property

    Energy Technology Data Exchange (ETDEWEB)

    Li, Xiaozhou [College of Science, Northwest A and F University, Yangling, Shaanxi 712100 (China); Wang, Lin, E-mail: wanglin0317@nwsuaf.edu.cn [College of Science, Northwest A and F University, Yangling, Shaanxi 712100 (China); Pei, Yuxin [College of Science, Northwest A and F University, Yangling, Shaanxi 712100 (China); Jiang, Jinqiang [State Key Lab of Applied Surface and Colloid Chemistry, College of Chemistry and Chemical Engineering, Shaanxi Normal University, Xi' an 710062 (China)

    2014-11-28

    Ultraviolet (UV) B is hazardous to human, plants and animals. With the rapid growth of ozone holes over the earth, the exploration of optical materials that can cut off harmful UV radiation is important. In this work, fusiform TiO{sub 2} nanoparticles were synthesized by a hydrothermal synthesis method. The thin films assembled with TiO{sub 2} nanoparticles and oppositely charged polyelectrolytes were fabricated via a layer-by-layer assembly method. The fabrication of poly(ethylene imine) (PEI)/TiO{sub 2} multilayer films was verified by ultraviolet–visible spectra measurements, scanning electron microscopy and atomic force microscopy. The as-prepared PEI/TiO{sub 2} multilayer films can effectively absorb harmful UVB light and filter off visible light. Most importantly, the PEI/TiO{sub 2} films can be deposited directly on various kinds of hydrophilic substrates such as quartz, glass, silicon and hydrophobic substrates such as polystyrene, polypropylene, polyethylene and polymethyl methacrylate when the hydrophilic substrates were modified to obtain a hydrophilic surface. - Highlights: • PEI/TiO{sub 2} films were fabricated via a layer-by-layer self-assembly method. • The films could effectively absorb harmful UVB light and filter off visible light. • The films could deposit directly on either hydrophilic or hydrophobic substrates.

  14. Hydration and physical performance.

    Science.gov (United States)

    Murray, Bob

    2007-10-01

    There is a rich scientific literature regarding hydration status and physical function that began in the late 1800s, although the relationship was likely apparent centuries before that. A decrease in body water from normal levels (often referred to as dehydration or hypohydration) provokes changes in cardiovascular, thermoregulatory, metabolic, and central nervous function that become increasingly greater as dehydration worsens. Similarly, performance impairment often reported with modest dehydration (e.g., -2% body mass) is also exacerbated by greater fluid loss. Dehydration during physical activity in the heat provokes greater performance decrements than similar activity in cooler conditions, a difference thought to be due, at least in part, to greater cardiovascular and thermoregulatory strain associated with heat exposure. There is little doubt that performance during prolonged, continuous exercise in the heat is impaired by levels of dehydration >or= -2% body mass, and there is some evidence that lower levels of dehydration can also impair performance even during relatively short-duration, intermittent exercise. Although additional research is needed to more fully understand low-level dehydration's effects on physical performance, one can generalize that when performance is at stake, it is better to be well-hydrated than dehydrated. This generalization holds true in the occupational, military, and sports settings.

  15. PEG-b-PPS-b-PEI micelles and PEG-b-PPS/PEG-b-PPS-b-PEI mixed micelles as non-viral vectors for plasmid DNA: tumor immunotoxicity in B16F10 melanoma.

    Science.gov (United States)

    Velluto, Diana; Thomas, Susan N; Simeoni, Eleonora; Swartz, Melody A; Hubbell, Jeffrey A

    2011-12-01

    Cationic micelles formed from poly(ethylene glycol)-bl-poly(propylene sulfide)-bl-poly(ethylene imine) (PEG-b-PPS-b-PEI) and from mixtures of poly(ethylene glycol)-bl-poly(propylene sulfide) (PEG-b-PPS) with PEG-b-PPS-b-PEI were explored as non-viral vectors for plasmid DNA (pDNA) transfection in a tumor immunotoxicity model. Complexes with pDNA were found to be templated exclusively by the size of the pDNA-free micelles and ranged from 240 nm (for PEG-b-PPS-b-PEI) to 30 nm (for mixed micelles of PEG-b-PPS/PEG-b-PPS-b-PEI). Both formulations transfected melanoma cells well in vitro. As a model with a functional read-out of tumor cell death, one with likely only small bystander effects, tumors were transfected with an antigen transgene, using an antigen to which the recipient animals had been previously vaccinated with a Th1-biasing adjuvant. Reduction in tumor growth, increase in intratumoral infiltration of cytotoxic T lymphocytes and accumulation of Th1-biasing cytokines indicated that both micelle formulations transfected efficiently compared with naked pDNA and with low cytotoxicity.

  16. Ductile flow of methane hydrate

    Science.gov (United States)

    Durham, W.B.; Stern, L.A.; Kirby, S.H.

    2003-01-01

    Compressional creep tests (i.e., constant applied stress) conducted on pure, polycrystalline methane hydrate over the temperature range 260-287 K and confining pressures of 50-100 MPa show this material to be extraordinarily strong compared to other icy compounds. The contrast with hexagonal water ice, sometimes used as a proxy for gas hydrate properties, is impressive: over the thermal range where both are solid, methane hydrate is as much as 40 times stronger than ice at a given strain rate. The specific mechanical response of naturally occurring methane hydrate in sediments to environmental changes is expected to be dependent on the distribution of the hydrate phase within the formation - whether arranged structurally between and (or) cementing sediments grains versus passively in pore space within a sediment framework. If hydrate is in the former mode, the very high strength of methane hydrate implies a significantly greater strain-energy release upon decomposition and subsequent failure of hydrate-cemented formations than previously expected.

  17. Some thermodynamical aspects of protein hydration water

    Energy Technology Data Exchange (ETDEWEB)

    Mallamace, Francesco, E-mail: francesco.mallamace@unime.it [Dipartimento di Fisica e Scienze della Terra, Università di Messina and CNISM, I-98168 Messina (Italy); Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Corsaro, Carmelo [Dipartimento di Fisica e Scienze della Terra, Università di Messina and CNISM, I-98168 Messina (Italy); CNR-IPCF, Viale F. Stagno D’Alcontres 37, I-98158 Messina (Italy); Mallamace, Domenico [Dipartimento SASTAS, Università di Messina, I-98166 Messina (Italy); Vasi, Sebastiano [Dipartimento di Fisica e Scienze della Terra, Università di Messina and CNISM, I-98168 Messina (Italy); Vasi, Cirino [CNR-IPCF, Viale F. Stagno D’Alcontres 37, I-98158 Messina (Italy); Stanley, H. Eugene [Center for Polymer Studies and Department of Physics, Boston University, Boston, Massachusetts 02215 (United States); Chen, Sow-Hsin [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-06-07

    We study by means of nuclear magnetic resonance the self-diffusion of protein hydration water at different hydration levels across a large temperature range that includes the deeply supercooled regime. Starting with a single hydration shell (h = 0.3), we consider different hydrations up to h = 0.65. Our experimental evidence indicates that two phenomena play a significant role in the dynamics of protein hydration water: (i) the measured fragile-to-strong dynamic crossover temperature is unaffected by the hydration level and (ii) the first hydration shell remains liquid at all hydrations, even at the lowest temperature.

  18. Alginate/PEI/DNA polyplexes: a new gene delivery system%藻酸盐/PEI/DNA复合载体作为一种新型基因递送系统

    Institute of Scientific and Technical Information of China (English)

    蒋革; 文相贤; 金美羅; 李东哲; 林美正; 廉荣一

    2006-01-01

    目的克服多聚乙烯亚胺(PEI,polyethlenimine)/DNA载体对细胞的毒性以及在含血清培养基里对癌细胞基因的转移率低的问题.方法利用具有水溶性、可生物降解的、并带有负电的藻酸盐(alginate)对PEI/DNA载体进行包衣,制备出复合载体,并在体外含50%血清培养基里,与PEI/DNA载体比较对C3癌细胞转染率.结果在含50%血清的培养基里,藻酸盐包衣制备的复合体载体[alginate:DNA,0.15(w/w);PEI:DNA,N:P=10]与PEI/DNA载体相比,对C3癌细胞基因转染率高出10~30倍,而且其表面正电荷数比PEI/DNA载体减少了一半,颗粒较小,并降低对细胞毒性和红血球集聚反应.结论作为新型的藻酸盐包衣制备的复合载体能提高在体外含高浓度血清培养基里对C3癌细胞的转染率,并能减少其对细胞毒性.%Aim To avoid the limitation of the use of cationic polyethlenimine (PEI)-complexed plasmid DNA use for in vitro or in vivo gene delivery due to its cytotoxicity and lower efficiency in the presence of serum. Methods A polyplex with decreased positive charge on the complex surface was designed. The PEI/DNA (PD) complexes coated with an anionic biodegradable polymer, alginate were prepared and their gene delivery behavior with PD was compared. Results The alginate-coated PD polyplex, where alginate: PEI: DNA [alginate: DNA, 0. 15 (w/w); PEI: DNA, N: P = 10] showed about 10 -30 fold-increased transfection efficiency compared to corresponding non-coated complexes to C3 cells in the presence of 50% serum. The surface charge of the alginate-coated complex was approximately half of that of the alginate-lacking complex. The size of alginate-coated complex was slightly smaller than that of the corresponding complex without alginate. The former complex also showed a reduced erythrocyte aggregation activity and decreased cytotoxicities to C3 cells in comparison with PD complex. Conclusion The alginate-coated PD polyplexes as a new gene delivery

  19. Formation and Dissociation of Methane Hydrates from Seawater in Consolidated Sand: Mimicking Methane Hydrate Dynamics beneath the Seafloor

    Directory of Open Access Journals (Sweden)

    Prasad B. Kerkar

    2013-11-01

    Full Text Available Methane hydrate formation and dissociation kinetics were investigated in seawater-saturated consolidated Ottawa sand-pack under sub-seafloor conditions to study the influence of effective pressure on formation and dissociation kinetics. To simulate a sub-seafloor environment, the pore-pressure was varied relative to confining pressure in successive experiments. Hydrate formation was achieved by methane charging followed by sediment cooling. The formation of hydrates was delayed with increasing degree of consolidation. Hydrate dissociation by step-wise depressurization was instantaneous, emanating preferentially from the interior of the sand-pack. Pressure drops during dissociation and in situ temperature controlled the degree of endothermic cooling within sediments. In a closed system, the post-depressurization dissociation was succeeded by thermally induced dissociation and pressure-temperature conditions followed theoretical methane-seawater equilibrium conditions and exhibited excess pore pressure governed by the pore diameter. These post-depressurization equilibrium values for the methane hydrates in seawater saturated consolidated sand-pack were used to estimate the enthalpy of dissociation of 55.83 ± 1.41 kJ/mol. These values were found to be lower than those reported in earlier literature for bulk hydrates from seawater (58.84 kJ/mol and pure water (62.61 kJ/mol due to excess pore pressure generated within confined sediment system under investigation. However, these observations could be significant in the case of hydrate dissociation in a subseafloor environment where dissociation due to depressurization could result in an instantaneous methane release followed by slow thermally induced dissociation. The excess pore pressure generated during hydrate dissociation could be higher within fine-grained sediments with faults and barriers present in subseafloor settings which could cause shifting in geological layers.

  20. Flow assurance intervention, hydrates remediation

    Energy Technology Data Exchange (ETDEWEB)

    Mancini, Christopher S. [Oceaneering International Inc., Houston, TX (United States)

    2012-07-01

    This paper addresses the issues of removing hydrates in sub sea flow lines and associated equipment with an Remotely Operated Vehicle (ROV) of opportunity and a multi-service-vessel (MSV). The paper is split into three topics: the equipment used with the ROV, assessing the interface points and handling fluids produced from drawing down the pressure. Each section is explained thoroughly and backed up with real world experience. The equipment section details information from actual jobs performed and why the particular components were utilized. The system is generally contained in an ROV mounted skid. Pumps are utilized to draw down the pressure inside the hydrated section of equipment, removing one of the three necessary components for hydrates formation. Once the section is pumped down, several options exist for handling the fluids pumped out of the system: pumping to surface, re-injection into the well, or injection into an operating flow line. This method of hydrates remediation is both economical and timely. Hydrate blockages form in low temperatures and high pressures. Reducing the pressure or increasing the temperature so the conditions lie to the right of the hydrate dissociation curve will slowly decompose the blockage. Depressurization and the use of MEG or methanol will give favorable conditions to remove the hydrate plug. Oceaneering has the capabilities to remove hydrates using the FRS in conjunction with an installation vessel to dispose of the gas and fluid removed from the flow line. Hydrate remediation techniques should be implemented into the initial design to reduce costs later. The cost of stopped production combined with the day rate for equipment needed for hydrate removal outweighs the costs if no technique is utilized. (author)

  1. 76 FR 22724 - Draft Program Environmental Impact Statement/Environmental Impact Report (PEIS/R) and Public...

    Science.gov (United States)

    2011-04-22

    ...) to reduce or avoid adverse water supply impacts to all of the Friant Division long-term contractors... alternatives considered in the Draft PEIS/R include actions that will be implemented to work towards achieving... contracts between the United States and the Central Valley Project (CVP) Friant Division contractors....

  2. Effect of polymer concentration on the structure and performance of PEI hollow fiber membrane contactor for CO2 stripping.

    Science.gov (United States)

    Naim, R; Ismail, A F

    2013-04-15

    A series of polyetherimide (PEI) hollow fiber membranes with various polymer concentrations (13-16 wt.%) for CO2 stripping process in membrane contactor application was fabricated via wet phase inversion method. The PEI membranes were characterized in terms of liquid entry pressure, contact angle, gas permeation and morphology analysis. CO2 stripping performance was investigated via membrane contactor system in a stainless steel module with aqueous diethanolamine as liquid absorbent. The hollow fiber membranes showed decreasing patterns in gas permeation, contact angle, mean pore size and effective surface porosity with increasing polymer concentration. On the contrary, wetting pressure of PEI membranes has enhanced significantly with polymer concentration. Various polymer concentrations have different effects on the CO2 stripping flux in which membrane with 14 wt.% polymer concentration showed the highest stripping flux of 2.7 × 10(-2)mol/m(2)s. From the performance comparison with other commercial membrane, it is anticipated that the PEI membrane has a good prospect in CO2 stripping via membrane contactor.

  3. Hydrated mineral stratigraphy of Ius Chasma, Valles Marineris

    Science.gov (United States)

    Roach, L.H.; Mustard, J.F.; Swayze, G.; Milliken, R.E.; Bishop, J.L.; Murchie, S.L.; Lichtenberg, K.

    2010-01-01

    New high-resolution spectral and morphologic imaging of deposits on walls and floor of Ius Chasma extend previous geomorphic mapping, and permit a new interpretation of aqueous processes that occurred during the development of Valles Marineris. We identify hydrated mineralogy based on visible-near infrared (VNIR) absorptions. We map the extents of these units with CRISM spectral data as well as morphologies in CTX and HiRISE imagery. Three cross-sections across Ius Chasma illustrate the interpreted mineral stratigraphy. Multiple episodes formed and transported hydrated minerals within Ius Chasma. Polyhydrated sulfate and kieserite are found within a closed basin at the lowest elevations in the chasma. They may have been precipitates in a closed basin or diagenetically altered after deposition. Fluvial or aeolian processes then deposited layered Fe/Mg smectite and hydrated silicate on the chasma floor, postdating the sulfates. The smectite apparently was weathered out of Noachian-age wallrock and transported to the depositional sites. The overlying hydrated silicate is interpreted to be an acid-leached phyllosilicate transformed from the underlying smectite unit, or a smectite/jarosite mixture. The finely layered smectite and massive hydrated silicate units have an erosional unconformity between them, that marks a change in surface water chemistry. Landslides transported large blocks of wallrock, some altered to contain Fe/Mg smectite, to the chasma floor. After the last episode of normal faulting and subsequent landslides, opal was transported short distances into the chasma from a few m-thick light-toned layer near the top of the wallrock, by sapping channels in Louros Valles. Alternatively, the material was transported into the chasma and then altered to opal. The superposition of different types of hydrated minerals and the different fluvial morphologies of the units containing them indicate sequential, distinct aqueous environments, characterized by alkaline

  4. Investigation on Gas Storage in Methane Hydrate

    Institute of Scientific and Technical Information of China (English)

    Zhigao Sun; Rongsheng Ma; Shuanshi Fan; Kaihua Guo; Ruzhu Wang

    2004-01-01

    The effect of additives (anionic surfactant sodium dodecyl sulfate (SDS), nonionic surfactant alkyl polysaccharide glycoside (APG), and liquid hydrocarbon cyclopentane (CP)) on hydrate induction time and formation rate, and storage capacity was studied in this work. Micelle surfactant solutions were found to reduce hydrate induction time, increase methane hydrate formation rate and improve methane storage capacity in hydrates. In the presence of surfactant, hydrate could form quickly in a quiescent system and the energy costs of hydrate formation were reduced. The critical micelle concentrations of SDS and APG water solutions were found to be 300× 10-6 and 500× 10-6 for methane hydrate formation system respectively. The effect of anionic surfactant (SDS) on methane storage in hydrates is more pronounced compared to a nonionic surfactant (APG). CP also reduced hydrate induction time and improved hydrate formation rate, but could not improve methane storage in hydrates.

  5. Coupling of a bifunctional peptide R13 to OTMCS-PEI copolymer as a gene vector increases transfection efficiency and tumor targeting

    Directory of Open Access Journals (Sweden)

    Lv H

    2014-03-01

    Full Text Available Hui Lv,1,* Qing Zhu,1,* Kewu Liu,2 Manman Zhu,1 Wenfang Zhao,1 Yuan Mao,1 Kehai Liu1 1Department of Biopharmaceutics, College of Food Science and Technology, Shanghai Ocean University, Shanghai, People's Republic of China; 2Heilongjiang Forest By-Product and Speciality Institute, Mudanjiang, People's Republic of China *These authors contributed equally to this work Background: A degradable polyethylenimine (PEI derivative coupled to a bifunctional peptide R13 was developed to solve the transfection efficiency versus cytotoxicity and tumor-targeting problems of PEI when used as a gene vector. Methods: We crossed-linked low molecular weight PEI with N-octyl-N-quaternary chitosan (OTMCS to synthesize a degradable PEI derivative (OTMCS-PEI, and then used a bifunctional peptide, RGDC-Tat (49–57 called R13 to modify OTMCS-PEI so as to prepare a new gene vector, OTMCS-PEI-R13. This new gene vector was characterized by various physicochemical methods. Its cytotoxicity and gene transfection efficiency were also determined both in vitro and in vivo. Results: The vector showed controlled degradation and excellent buffering capacity. The particle size of the OTMCS-PEI-R13/DNA complexes was around 150–250 nm and the zeta potential ranged from 10 mV to 30 mV. The polymer could protect plasmid DNA from being digested by DNase I at a concentration of 23.5 U DNase I/µg DNA. Further, the polymer was resistant to dissociation induced by 50% fetal bovine serum and 400 µg/mL sodium heparin. Compared with PEI 25 kDa, the OTMCS-PEI-R13/DNA complexes showed higher transfection efficiency both in vitro and in vivo. Further, compared with OTMCS-PEI, distribution of OTMCS-PEI-R13 at tumor sites was markedly enhanced, indicating the tumor-targeting specificity of R13. Conclusion: OTMCS-PEI-R13 could be a potential candidate as a safe and efficient gene delivery carrier for gene therapy. Keywords: nonviral gene vector, polyethylenimine, R13, transfection efficiency

  6. 聚四氟乙烯和石墨对聚醚酰亚胺摩擦学性能的影响%Tribological Properties of PTFE/PEI and Graphite/PEI Blends

    Institute of Scientific and Technical Information of China (English)

    马彦琼; 谭忠阳; 李玉杰; 王大明; 党国栋; 陈春海

    2014-01-01

    The tribological performances of polyetherimide( PEI) composite materials filled with polytetraflu-oroethylene( PTFE) and graphite were evaluated on UMT-2 friction and wear tester, respectively. The micro-structures of worn surfaces, cross-sections of the PEI composite were examined with scanning electron micro-scope( SEM) , and wear mechanism was analyzed. The result showed that PEI composite filled with PTFE and graphite were improved significantly on friction and wear properties. The friction coefficient is reduced to below 0. 3(the friction coefficient of pure PEI is 0. 41), the wear rate is reduced by 3 orders of magnitude. When filled with 10%PTFE in composites PTFE system, the friction coefficient of the composites is lowest, and the friction coefficient of the graphite counterpart is lowest in 15% graphite content. The lowest friction coefficient is 0. 23 and 0. 27. For the wear rate, PEI composite materials filled with PTFE and graphite are both de-creased with the content increasing respectively. Consequently, compared with the PEI composite materials filled with graphite, the PEI composite materials filled with PTFE has more excellent tribological performance and mechanical behavior. The mechanical behavior of two kinds of the PEI composites was also measured, such as tensile strength, bending strength, impact strength and Rockwell hardness. The results show that, when the mass fraction of 5%—15%, which is the best tribological performance improvement in addition, comprehensive mechanical properties of blends of materials is still good.%将聚四氟乙烯( PTFE)和石墨两类减摩耐磨填料填充到聚醚酰亚胺( PEI)中,表征其摩擦性能,利用扫描电子显微镜分析了磨损表面的显微结构,并分析了磨损机制.研究结果表明, PTFE和石墨的填充明显改善了PEI的摩擦磨损性,摩擦系数降低到0.3以下(纯PEI的摩擦系数为0.41),磨损率降低了3个数量级.在PTFE体系中, PTFE

  7. Hydrates fighting tools; Des outils de lutte contre les hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    2003-04-01

    Shell Exploration and Production company (SEPCo) is the operator of the 'Popeye' deep offshore field in the Gulf of Mexico. Thanks to the introduction of a low dosing hydrates inhibitor (LDHI) elaborated by Shell Global Solutions, the company has added a 7.5 Gpc extra volume of gas to its recoverable reserves. This new technology avoids the plugging of pipes by hydrates formation. (J.S.)

  8. Determination of Nucleic Acid Hydration Using Osmotic Stress

    Science.gov (United States)

    Rozners, Eriks

    2010-01-01

    Understanding the role water plays in biological processes requires detailed knowledge of the phenomena of biopolymer hydration. Crystal structures have identified exact sites occupied by the water molecules in immediate hydration layers. NMR and molecular modeling have provided information on dynamics of water molecules occupying these sites. However, these studies give little information on the thermodynamic contribution of water molecules to conformational equilibria and recognition affinity. This unit describes probing of nucleic acid hydration using osmotic stress, a method that provides thermodynamic information complementary to crystallography, NMR and molecular modeling. Osmotic stress monitors the depression of melting temperature upon decreasing the water activity and calculates the number of thermodynamically unique water molecules associated with the double helix and released from the single strands upon melting. PMID:21154532

  9. Comparison of the physical and geotechnical properties of gas-hydrate-bearing sediments from offshore India and other gas-hydrate-reservoir systems

    Science.gov (United States)

    Winters, William J.; Wilcox-Cline, R.W.; Long, P.; Dewri, S.K.; Kumar, P.; Stern, Laura A.; Kerr, Laura A.

    2014-01-01

    The sediment characteristics of hydrate-bearing reservoirs profoundly affect the formation, distribution, and morphology of gas hydrate. The presence and type of gas, porewater chemistry, fluid migration, and subbottom temperature may govern the hydrate formation process, but it is the host sediment that commonly dictates final hydrate habit, and whether hydrate may be economically developed.In this paper, the physical properties of hydrate-bearing regions offshore eastern India (Krishna-Godavari and Mahanadi Basins) and the Andaman Islands, determined from Expedition NGHP-01 cores, are compared to each other, well logs, and published results of other hydrate reservoirs. Properties from the hydrate-free Kerala-Konkan basin off the west coast of India are also presented. Coarser-grained reservoirs (permafrost-related and marine) may contain high gas-hydrate-pore saturations, while finer-grained reservoirs may contain low-saturation disseminated or more complex gas-hydrates, including nodules, layers, and high-angle planar and rotational veins. However, even in these fine-grained sediments, gas hydrate preferentially forms in coarser sediment or fractures, when present. The presence of hydrate in conjunction with other geologic processes may be responsible for sediment porosity being nearly uniform for almost 500 m off the Andaman Islands.Properties of individual NGHP-01 wells and regional trends are discussed in detail. However, comparison of marine and permafrost-related Arctic reservoirs provides insight into the inter-relationships and common traits between physical properties and the morphology of gas-hydrate reservoirs regardless of location. Extrapolation of properties from one location to another also enhances our understanding of gas-hydrate reservoir systems. Grain size and porosity effects on permeability are critical, both locally to trap gas and regionally to provide fluid flow to hydrate reservoirs. Index properties corroborate more advanced

  10. Obsidian hydration dates glacial loading?

    Science.gov (United States)

    Friedman, I; Pierce, K L; Obradovich, J D; Long, W D

    1973-05-18

    Three different groups of hydration rinds have been measured on thin sections of obsidian from Obsidian Cliff, Yellowstone National Park, Wyoming. The average thickness of the thickest (oldest) group of hydration rinds is 16.3 micrometers and can be related to the original emplacement of the flow 176,000 years ago (potassium-argon age). In addition to these original surfaces, most thin sections show cracks and surfaces which have average hydration rind thicknesses of 14.5 and 7.9 micrometers. These later two hydration rinds compare closely in thickness with those on obsidian pebbles in the Bull Lake and Pinedale terminal moraines in the West Yellowstone Basin, which are 14 to 15 and 7 to 8 micrometers thick, respectively. The later cracks are thought to have been formed by glacial loading during the Bull Lake and Pinedale glaciations, when an estimated 800 meters of ice covered the Obsidian Cliff flow.

  11. Synthesis, and Characterization, and Evaluation of Cellular Effects of the FOL-PEG-g-PEI-GAL Nanoparticles as a Potential Non-Viral Vector for Gene Delivery

    Directory of Open Access Journals (Sweden)

    S. Ghiamkazemi

    2010-01-01

    Full Text Available In this manuscript, we synthesized the potential non viral vector for gene delivery with proper transfection efficiency and low cytotoxicity. Polyethylenimine (PEI is a well-known cationic polymer which has high positive surface charge for condensing plasmid DNA. However; it is highly cytotoxic in many cell lines because of the high surface charge, non-biodegradability and non-biocompatibility. To enhance PEI biodegradability, the graft copolymer “PEG-g-PEI” was synthesized. To target cancer liver cells, two targeting ligands folic acid and galactose (lactobionic acid which are over expressed on human hepatocyte carcinoma were attached to graft copolymer and “FOL-PEG-g-PEI-GAL” copolymer was synthesized. Composition of this grafted copolymer was characterized using 1H-NMR and FTIR spectra. The molecular weight and zeta potential of this copolymer was compared to PEI. The particle size and zeta potential of FOL-PEG-g-PEI-GAL/DNA complexes at various N/P ratio were measured using dynamic light scattering (DLS. Cytotoxicity of the copolymer was also studied in cultured HepG2 human hepatoblastoma cell line. The FOL-PEG-g-PEI-GAL/DNA complexes at various N/P ratios exhibited no cytotoxicity in HepG2 cell line compared to PEI 25K as a control. The novel copolymer showed enhanced biodegradability in physiological conditions in compared with PEI and targeted cultured HepG2 cells. More importantly, significant transfection efficiency was exhibited in cancer liver cells. Together, our results showed that “FOL-PEG-g-PEI-GAL” nanoparticals could be considered as a useful non-viral vector for targeted gene delivery.

  12. Haemocytic leukemia in Prince Edward Island (PEI) soft shell clam (Mya arenaria): Spatial distribution in agriculturally impacted estuaries

    Energy Technology Data Exchange (ETDEWEB)

    Muttray, Annette, E-mail: amuttray@rescan.com [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada); Reinisch, Carol, E-mail: creinisch@mbl.edu [Visiting Scientist Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada); Miller, Jason, E-mail: j.miller@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada); Ernst, William, E-mail: bill.ernst@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 45 Alderney Drive, Dartmouth, NS, Canada B2Y 2N6 (Canada); Gillis, Patricia, E-mail: patty.gillis@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada); Losier, Melanie, E-mail: melanie.losier@ec.gc.ca [Environment Canada, Atlantic Laboratory for Environmental Testing, Environmental Science Centre, P.O. Box 23005 Moncton, NB, Canada E1A 6S8 (Canada); Sherry, James, E-mail: jim.sherry@ec.gc.ca [Environment Canada, Water Science and Technology Directorate, 867 Lakeshore Road, Burlington, ON, Canada L7R 4A6 (Canada)

    2012-05-01

    Intensive farming of potatoes in Prince Edward Island (PEI) relies on the repeated and widespread application of fertilizers and pesticides. In PEI the main potato farming areas are in close proximity and drain directly to estuaries. Runoff from high agricultural activity watersheds could impact benthic organism health in the depositional zone of downstream estuaries. The estuarine filter feeder Mya arenaria (soft-shell clam) could be particularly vulnerable to both particle-adsorbed and water soluble contaminants. M. arenaria is susceptible to haemocytic leukemia. In May 2009, we established that heavily proliferated leukemia (HPL) prevalence was generally higher in PEI estuaries located downstream of high intensity potato farming (Dunk and Wilmot estuaries) watersheds than in estuaries downstream of lower intensity areas. Using Mab-1E10 based immunocytochemistry we observed that leukemic haemocytes from the Dunk and Wilmot estuaries were 1E10 negative whereas those from the Ox/Sheep estuary (low potato farming intensity) were 1E10 positive. The expression of genes in the p53 tumour suppressor pathway enabled us to differentiate groups of leukemic and normal M. arenaria, validating our diagnoses. In October 2009, we confirmed that HPL prevalence was elevated in the Dunk and Wilmot estuaries compared to reference (Souris River). Moreover, leukemia prevalence declined with distance from the river mouths along transects through the Dunk and Wilmot estuaries. The pesticides ss-endosulfan and {alpha}-endosulfan were detected in surface sediments from the Dunk and Wilmot estuaries, but not in sediments from either the Souris River or several other lower intensity potato farming watersheds. Our study provides evidence of an association between intensity of potato farming and prevalence of clam leukemia at downstream estuaries in PEI. - Highlights: Black-Right-Pointing-Pointer We examined leukemia prevalence in PEI clams Mya arenaria. Black

  13. Storing natural gas as frozen hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Gudmundsson, J.S.; Khokhar, A.A. (Univ. of Trondheim (Norway)); Parlaktuna, M. (Middle East Technical Univ., Ankara (Turkey))

    1994-02-01

    The formation of natural gas hydrates is a well-known problem in the petroleum and natural gas industries. Hydrates are solid materials that form when liquid water and natural gas are brought in contact under pressure. Hydrate formation need not be a problem. On the contrary, it can be an advantage. The volume of hydrates is much less than that of natural gas. At standard conditions, hydrates occupy 150 to 170 times less volume than the corresponding gas. Typically, natural gas hydrates contain 15% gas and 85% water by mass. It follows that hydrates can be used for large-scale storage of natural gas. Benesh proposed using hydrates to improve the load factor of natural gas supply systems. The author suggested that hydrates could be produced by bringing liquid water into contact with natural gas at the appropriate temperature and high pressure. The hydrate then would be stored at a temperature and pressure where it was stable. When gas was needed for the supply system, the hydrate would be melted at low pressure. The stability of a natural gas hydrate during storage at atmospheric pressure and below-freezing temperatures was studied in the laboratory. The gas hydrate was produced in a stirred vessel at 2- to 6-MPa pressure and temperatures from 0 to 20 C. The hydrate was refrigerated and stored in deep freezers at [minus]5, [minus]10, and [minus]18 C for up to 10 days. The natural gas hydrate remained stable when kept frozen at atmospheric pressure.

  14. Airway Hydration and COPD

    Science.gov (United States)

    Ghosh, Arunava; Boucher, R.C.; Tarran, Robert

    2015-01-01

    Chronic obstructive pulmonary disease (COPD) is one of the prevalent causes of worldwide mortality and encompasses two major clinical phenotypes, i.e., chronic bronchitis (CB) and emphysema. The most common cause of COPD is chronic tobacco inhalation. Research focused on the chronic bronchitic phenotype of COPD has identified several pathological processes that drive disease initiation and progression. For example, the lung’s mucociliary clearance (MCC) system performs the critical task of clearing inhaled pathogens and toxic materials from the lung. MCC efficiency is dependent on: (i) the ability of apical plasma membrane ion channels such as the cystic fibrosis transmembrane conductance regulator (CFTR) and the epithelial Na+ channel (ENaC) to maintain airway hydration; (ii) ciliary beating; and, (iii) appropriate rates of mucin secretion. Each of these components is impaired in CB and likely contributes to the mucus stasis/accumulation seen in CB patients. This review highlights the cellular components responsible for maintaining MCC and how this process is disrupted following tobacco exposure and with CB. We shall also discuss existing therapeutic strategies for the treatment of chronic bronchitis and how components of the MCC can be used as biomarkers for the evaluation of tobacco or tobacco-like-product exposure. PMID:26068443

  15. Mechanism of gypsum hydration

    Directory of Open Access Journals (Sweden)

    Pacheco, G.

    1991-06-01

    Full Text Available There is an hypothesis that the mechanism o f gypsum hydration and dehydration is performed through two simultaneous phenomena. In this study we try to clear up this phenomenon using chlorides as accelerators or a mixture of ethanol-methanol as retarders to carry out the gypsum setting. Natural Mexican gypsum samples and a hemihydrate prepared in the laboratory are used. The following analytical techniques are used: MO, DRX, DTA, TG and DTG. In agreement with the obtained results, it can be concluded: that colloid formation depends on the action of accelerators or retarders and the crystals are a consequence of the quantity of hemihydrate formed.

    En el mecanismo de hidratación y deshidratación del yeso existe la hipótesis de que éste se efectúa por dos fenómenos simultáneos. Este estudio intenta esclarecer estos fenómenos, empleando: cloruros como aceleradores o mezcla etanol-metanol como retardadores para efectuar el fraguado del yeso. Se emplean muestras de yeso de origen natural mexicano y hemihydrate preparado en laboratorio; se utilizan técnicas analíticas: MO, DRX, DTA, TG y DTG. De acuerdo a los resultados obtenidos se puede deducir: que la formación del coloide depende de la acción de los agentes aceleradores o retardadores y que los cristales son consecuencia de la cantidad de hemihidrato formado.

  16. miRNA oligonucleotide and sponge for miRNA-21 inhibition mediated by PEI-PLL in breast cancer therapy.

    Science.gov (United States)

    Gao, Shiqian; Tian, Huayu; Guo, Ye; Li, Yuce; Guo, Zhaopei; Zhu, Xiaojuan; Chen, Xuesi

    2015-10-01

    MicroRNA-21 (miR-21) inhibition is a promising biological strategy for breast cancer therapy. However its application is limited by the lack of efficient miRNA inhibitor delivery systems. As a cationic polymer transfection material for nucleic acids, the poly (l-lysine)-modified polyethylenimine (PEI-PLL) copolymer combines the high transfection efficiency of polyethylenimine (PEI) and the good biodegradability of polyllysine (PLL). In this work, PEI-PLL was successfully synthesized and confirmed to transfect plasmid and oligonucleotide more effectively than PEI in MCF-7 cells (human breast cancer cells). In this regard, two kinds of miR-21 inhibitors, miR-21 sponge plasmid DNA (Sponge) and anti-miR-21 oligonucleotide (AMO), were transported into MCF-7 cells by PEI-PLL respectively. The miR-21 expression and the cellular physiology were determined post transfection. Compared with the negative control, PEI-PLL/Sponge or PEI-PLL/AMO groups exhibited lower miR-21 expression and cell viability. The anti-tumor mechanism of PEI-PLL/miR-21 inhibitors was further studied by cell cycle and western blot analyses. The results indicated that the miR-21 inhibition could induce the cell cycle arrest in G1 phase, upregulate the expression of Programmed Cell Death Protein 4 (PDCD4) and thus active the caspase-3 apoptosis pathway. Interestingly, the PEI-PLL/Sponge and PEI-PLL/AMO also sensitized the MCF-7 cells to anti-tumor drugs, doxorubicin (DOX) and cisplatin (CDDP). These results demonstrated that PEI-PLL/Sponge and PEI-PLL/AMO complexes would be two novel and promising gene delivery systems for breast cancer gene therapy based on miR-21 inhibition. This work was a combination of the high transfection efficiency of polyethylenimine (PEI), the good biodegradability of polyllysine (PLL) and the breast cancer-killing effect of miR-21 inhibitors. The poly (l-lysine)-modified polyethylenimine (PEI-PLL) copolymer was employed as the vector of miR-21 sponge plasmid DNA (Sponge) or

  17. Formation of natural gas hydrates in marine sediments. Gas hydrate growth and stability conditioned by host sediment properties

    Science.gov (United States)

    Clennell, M.B.; Henry, P.; Hovland, M.; Booth, J.S.; Winters, W.J.; Thomas, M.

    2000-01-01

    The stability conditions of submarine gas hydrates (methane clathrates) are largely dictated by pressure, temperature, gas composition, and pore water salinity. However, the physical properties and surface chemistry of the host sediments also affect the thermodynamic state, growth kinetics, spatial distributions, and growth forms of clathrates. Our model presumes that gas hydrate behaves in a way analogous to ice in the pores of a freezing soil, where capillary forces influence the energy balance. Hydrate growth is inhibited within fine-grained sediments because of the excess internal phase pressure of small crystals with high surface curvature that coexist with liquid water in small pores. Therefore, the base of gas hydrate stability in a sequence of fine sediments is predicted by our model to occur at a lower temperature, and so nearer to the seabed than would be calculated from bulk thermodynamic equilibrium. The growth forms commonly observed in hydrate samples recovered from marine sediments (nodules, sheets, and lenses in muds; cements in sand and ash layers) can be explained by a requirement to minimize the excess of mechanical and surface energy in the system.

  18. Selective and reactive hydration of nitriles to amides in water using silver nanoparticles stabilized by organic ligands

    Energy Technology Data Exchange (ETDEWEB)

    Kawai, Koji [Hokkaido University, Division of Materials Science and Engineering, Faculty of Engineering (Japan); Kawakami, Hayato [Miyoshi Oil & Fat Co., Ltd. (Japan); Narushima, Takashi; Yonezawa, Tetsu, E-mail: tetsu@eng.hokudai.ac.jp [Hokkaido University, Division of Materials Science and Engineering, Faculty of Engineering (Japan)

    2015-02-15

    Water-dispersible silver nanoparticles stabilized by silver–carbon covalent bonds were prepared. They exhibited high catalytic activities for the selective hydration of nitriles to amides in water. The activation of a nitrile group by the functional groups of the substrates and the hydrophobic layer on the nanoparticles influenced the catalyzed reaction were confirmed. Alkyl nitriles could also be selectively hydrated.

  19. High-resolution well-log derived dielectric properties of gas-hydrate-bearing sediments, Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    Science.gov (United States)

    Sun, Y.; Goldberg, D.; Collett, T.; Hunter, R.

    2011-01-01

    A dielectric logging tool, electromagnetic propagation tool (EPT), was deployed in 2007 in the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well (Mount Elbert Well), North Slope, Alaska. The measured dielectric properties in the Mount Elbert well, combined with density log measurements, result in a vertical high-resolution (cm-scale) estimate of gas hydrate saturation. Two hydrate-bearing sand reservoirs about 20 m thick were identified using the EPT log and exhibited gas-hydrate saturation estimates ranging from 45% to 85%. In hydrate-bearing zones where variation of hole size and oil-based mud invasion are minimal, EPT-based gas hydrate saturation estimates on average agree well with lower vertical resolution estimates from the nuclear magnetic resonance logs; however, saturation and porosity estimates based on EPT logs are not reliable in intervals with substantial variations in borehole diameter and oil-based invasion.EPT log interpretation reveals many thin-bedded layers at various depths, both above and below the thick continuous hydrate occurrences, which range from 30-cm to about 1-m thick. Such thin layers are not indicated in other well logs, or from the visual observation of core, with the exception of the image log recorded by the oil-base microimager. We also observe that EPT dielectric measurements can be used to accurately detect fine-scale changes in lithology and pore fluid properties of hydrate-bearing sediments where variation of hole size is minimal. EPT measurements may thus provide high-resolution in-situ hydrate saturation estimates for comparison and calibration with laboratory analysis. ?? 2010 Elsevier Ltd.

  20. Evaluation of the Passive Cooling Strategies for Pei Min Sport Complex

    Science.gov (United States)

    Yam, K. S.; Yem, W. L.; Lee, V. C. C.

    2017-07-01

    This paper presents a modelling study on the evaluation of the passive cooling strategies for Pei Min sport complex at Miri. The squash centre has experienced excessively high temperature during peak hours that results in complains from the users. We discussed several passive cooling mechanisms and proposed four strategies for the sport centre. Thermal energy simulations were performed on these strategies using OpenStudio to evaluate their impact on the hourly temperature profile within the building. It was found that the peak temperature during the noon was significantly reduced when conductive material was applied at the lower surface of the roof, and the top of the roof was coated with white paint. However, insulating the roof also leads to weaker heat dispersion from the building which lower the rate of temperature drop in the late afternoon. Partitioning the roof was found to have similar effect as insulating roof. Air infiltration is essential for promoting air movement and regulating the temperature within the building. It was found the complex already have sufficient opening for the full effect of air infiltration.

  1. PEI De-kai (裴德恺)A Prominent Pathophysiologist

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    @@PEI De-kai, male, was born in Shanghai, China, on June 8, 1928. His native place was Danyang, Jiangsu Province and he was graduated from Dalian Medical College in 1954. He holds some posts in several departments, such as the pathophysiologic professor, the academic comittee member and the head of basic research section in the Institute of Acute Abdomen in Dalian Medical University. His titles in learned society were the deputy-director of the Acute Abdomen Speciality Committee, Chinese Association of the Integration of Traditional and Western Medicine, and also in its Liaoning Branch; the deputy-director of Digestion Committee in Chinese Association of Pathophysiology, and the director of its branch in Dalian. He also holds some concurrent posts, such as the sanitary specialist of consultative committee and the researcher specially invited by Dalian municipality. As a professor, research fellow, and consultant, he was appointed by China Academy of Traditional Chinese Medicine, Dalian Institute of Medical Science, the Hospital of Integration of Traditional and Western Medicine in Dalian, and the Gallstone Research Center of State Administration of Traditional Chinese Medicine respectively.

  2. Constraining gas hydrate occurrence in the northern Gulf of Mexico continental slope : fine scale analysis of grain-size in hydrate-bearing sediments

    Energy Technology Data Exchange (ETDEWEB)

    Hangsterfer, A.; Driscoll, N.; Kastner, M. [Scripps Inst. of Oceanography, La Jolla, CA (United States). Geosciences Research Division

    2008-07-01

    Methane hydrates can form within the gas hydrate stability zone (GHSZ) in sea beds. The Gulf of Mexico (GOM) contains an underlying petroleum system and deeply buried, yet dynamic salt deposits. Salt tectonics and fluid expulsion upward through the sediment column result in the formation of fractures, through which high salinity brines migrate into the GHSZ, destabilizing gas hydrates. Thermogenic and biogenic hydrocarbons also migrate to the seafloor along the GOMs northern slope, originating from the thermal and biogenic degradation of organic matter. Gas hydrate occurrence can be controlled by either primary permeability, forming in coarse-grained sediment layers, or by secondary permeability, forming in areas where hydrofracture and faulting generate conduits through which hydrocarbon-saturated fluids flow. This paper presented a study that attempted to determine the relationship between grain-size, permeability, and gas hydrate distribution. Grain-size analyses were performed on cores taken from Keathley Canyon and Atwater Valley in the GOM, on sections of cores that both contained and lacked gas hydrate. Using thermal anomalies as proxies for the occurrence of methane hydrate within the cores, samples of sediment were taken and the grain-size distributions were measured to see if there was a correlation between gas hydrate distribution and grain-size. The paper described the methods, including determination of hydrate occurrence and core analysis. It was concluded that gas hydrate occurrence in Keathley Canyon and Atwater Valley was constrained by secondary permeability and was structurally controlled by hydrofractures and faulting that acted as conduits through which methane-rich fluids flowed. 11 refs., 2 tabs., 5 figs.

  3. Polyethylenimine (PEI)-g-comb-poly(ethylene glycol)-transferrin(Ⅰ):Tumor-targeted Vector for Gene Delivery In-vitro

    Institute of Scientific and Technical Information of China (English)

    Gu Ping TANG; Zhi Yu WANG

    2006-01-01

    The work described the synthesis and evaluation of PEI-g-comb-PEG-transferrin as a potential system for gene therapy in vitro. The MW of PEG was 10KDa, and PEI was 2KDa.Its structure was identified by NMR, FT-IR and TGA spectroscopy. MTT assay found that at concentration up to 4000 n mol/L of the polymer, cell viability was over 85%. The bio-character of polymer/DNA complex was characterized by agarose gel electrophoresis, ethidium bromide exclusion and zeta-potential assay. The polymer could retardate DNA at N/P ratio 3.0-3.5 (mol/mol). The particle size of the polymer/DNA complex was less than 300 nm. Transfection efficiency of the complex was studied in COS7 and NT2 cell lines.

  4. A Study on Zhu Pei's View on The Book of Songs%朱霈诗经学论略

    Institute of Scientific and Technical Information of China (English)

    朱宏胜

    2012-01-01

    朱霈治《诗》颇具怀疑精神,其以《氓》为异国之人淫于外州;《鸡鸣》为太师所奏乐曲;《无衣》为关武公;《采蘩》非夫人亲蚕之作;《汉广》诗与婚嫁有关。如此等等,敢于质疑前贤,自出新解。%Zhu Pei had the spirit of skepticism when he studied The Book of Songs. In his view, Meng is a poem which portraits a stranger in Wei; Ji Ming is a piece of music played by senior grand tutors; Wu Yi is a poem which praises Wu Gong; Hart Guang is a piece of poetry related to marriage, etc. Zhu Pei dared to question his predecessors, and speak out his own opinion.

  5. Non-Covalently Functionalized of Single-Walled Carbon Nanotubes by DSPE-PEG-PEI for SiRNA Delivery.

    Science.gov (United States)

    Siu, King Sun; Zhang, Yujuan; Zheng, Xiufen; Koropatnick, James; Min, Wei-Ping

    2016-01-01

    The expression of a gene can be specifically downregulated by small interfering RNA (SiRNA). Modified carbon nanotubes (CNT) can be used to protect SiRNA and facilitate its entry into cells. Regardless of that, simple and efficient functionalization of CNT is lacking. Effective SiRNA delivery can be carried out using non-covalently functionalized CNT, where non-covalent (versus covalent) functionalization is simpler and more expeditious. Non-covalently functionalized single walled carbon nanotubes (SWCNT) that include a lipopolymer are described here. Polyethylenimine (PEI) conjugated to 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE-PEG) was generated and the products used to disperse CNT to form DSPE-PEG-PEI/CNT (DGI/C), an agent capable of facilitating SiRNA delivery to cells in vitro and organs and cells in vivo.

  6. Star-shaped copolymer grafted PEI and REDV as a gene carrier to improve migration of endothelial cells.

    Science.gov (United States)

    Lv, Juan; Hao, Xuefang; Li, Qian; Akpanyung, Mary; Nejjari, Abdelilah; Neve, Agnaldo Luis; Ren, Xiangkui; Feng, Yakai; Shi, Changcan; Zhang, Wencheng

    2017-01-17

    In this work, a biodegradable star-shaped copolymer poly(lactide-co-3(S)-methyl-morpholine-2,5-dione)6 (Star-(PLMD)6) was synthesized via ring-opening polymerization (ROP), and subsequently a gene carrier Star-PLMD-g-PEI-g-PEG-CREDVW was prepared by grafting polyethyleneimine (PEI), polyethylene glycol (PEG) and targeting peptide REDV onto Star-(PLMD)6. This gene carrier could form stable micelles to condense pEGFP-ZNF580 through electrostatic interaction. The resulting complexes were biocompatible and showed high efficiency in gene delivery. In addition, these complexes exhibited high selectivity for endothelial cells (ECs), high transfection efficiency and enhanced migration of ECs. The protein level of ZNF580 expression was significantly high (up to 85%), while the control group was only 51%. This combination of degradability, targeting ligand and star-structure strategy exhibits a significant advantage in transfection efficiency and migration of ECs.

  7. Tetrahydrofuran hydrate decomposition characteristics in porous media

    Science.gov (United States)

    Song, Yongchen; Wang, Pengfei; Wang, Shenglong; Zhao, Jiafei; Yang, Mingjun

    2016-12-01

    Many tetrahydrofuran (THF) hydrate properties are similar to those of gas hydrates. In the present work THF hydrate dissociation in four types of porous media is studied. THF solution was cooled to 275.15 K with formation of the hydrate under ambient pressure, and then it dissociated under ambient conditions. THF hydrate dissociation experiments in each porous medium were conducted three times. Magnetic resonance imaging (MRI) was used to obtain images. Decomposition time, THF hydrate saturation and MRI mean intensity (MI) were measured and analyzed. The experimental results showed that the hydrate decomposition time in BZ-4 and BZ-3 was similar and longer than that in BZ-02. In each dissociation process, the hydrate decomposition time of the second and third cycles was shorter than that of the first cycle in BZ-4, BZ-3, and BZ-02. The relationship between THF hydrate saturation and time is almost linear.

  8. Two-Sided Surface Oxidized Cellulose Membranes Modified with PEI: Preparation, Characterization and Application for Dyes Removal

    OpenAIRE

    Wei Wang; Qian Bai; Tao Liang; Huiyu Bai; Xiaoya Liu

    2017-01-01

    Porous regenerated cellulose (RC) membranes were prepared with cotton linter pulp as a raw material. These membranes were first oxidized on both sides by a modified (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO) oxidation system using a controlled oxidation reaction technique. Then, the oxidized RC membranes were functionalized with polyethylenimine (PEI) via the glutaraldehyde crosslinking method to obtain bifunctional (carboxyl and amino) porous RC membranes, as revealed by Fourier transfo...

  9. XPS of fast-frozen hematite colloids in NaCl aqueous solutions: I. Evidence for the formation of multiple layers of hydrated sodium and chloride ions induced by the {001} basal plane

    Energy Technology Data Exchange (ETDEWEB)

    Shchukarev, Andrei; Boily, Jean F.; Felmy, Andrew R.

    2007-12-13

    The influence of the {001} basal plane of hematite on the composition of fast-frozen centrifuged wet pastes of hematite prepared at pH 4 and 9 and at ionic strengths of 0, 10 and 100 mM NaCl was investigated by x-ray photoelectron spectroscopy. Two hematite preparations consisted of micrometer-sized platelets with 42% (HEM-1) and 95% (HEM-8) of the surface terminated by the {001} basal plane. A third preparation of spherical shape with no recognizable crystal plane (HEM-control) was used as a control to these experiments. All hematite samples responded to changes in pH and ionic strength, showing that acid/base reactions of surface hydroxyl groups control the composition of the paste. The HEM-1 and HEM-8 sample exhibited divergent properties at the highest ionic strength (100 mM) with energy loss features in the Na 1s and Cl 2p spectra and an important water content. As the spectra were typical of hydrated Na+ and Cl- ions and that the surface concentrations were unusually large, the HEM-1 and HEM-8 samples are proposed to induce the formation of a three-dimensional distribution of these ions in the paste. The sodium, chloride and water content was also correlated to the fraction of the {001} basal plane present in the sample and provided evidence for an approximate stochiometric Na:Cl:H2O ratio of 1:1:2. The {001} basal plane of hematite is consequently proposeD to be the cause of this feature.

  10. Amperometric detection of lactose using β-galactosidase immobilized in layer-by-layer films.

    Science.gov (United States)

    Campos, Paula P; Moraes, Marli L; Volpati, Diogo; Miranda, Paulo B; Oliveira, Osvaldo N; Ferreira, Marystela

    2014-07-23

    A direct, low-cost method to determine the concentration of lactose is an important goal with possible impact in various types of industry. In this study, a biosensor is reported that exploits the specific interaction between lactose and the enzyme β-galactosidase (β-Gal) normally employed to process lactose into glucose and galactose for lactose-intolerant people. The biosensor was made with β-Gal immobilized in layer-by-layer (LbL) films with the polyelectrolyte poly(ethylene imine) (PEI) and poly(vinyl sufonate) (PVS) on an indium tin oxide (ITO) electrode modified with a layer of Prussian Blue (PB). With an ITO/PB/(PEI/PVS)1(PEI/β-Gal)30 architecture, lactose could be determined with an amperometric method with sensitivity of 0.31 μA mmol(-1) cm(-2) and detection limit of 1.13 mmol L(-1), which is sufficient for detecting lactose in milk and for clinical exams. Detection occurred via a cascade reaction involving glucose oxidase titrated as electrolytic solution in the electrochemical cell, while PB allowed for operation at 0.0 V versus saturated calomel electrode, thus avoiding effects from interfering species. Sum-frequency generation spectroscopy data for the interface between the LbL film and a buffer containing lactose indicated that β-Gal lost order, which is the first demonstration of structural effects induced by the molecular recognition interaction with lactose.

  11. The Effect of PEI and PVP-Stabilized Gold Nanoparticles on Equine Platelets Activation: Potential Application in Equine Regenerative Medicine

    Directory of Open Access Journals (Sweden)

    Mateusz Hecold

    2017-01-01

    Full Text Available The aim of this work was to assess the effect of different stabilizing agents, for example, polyethylenimine (PEI and polyvinylpyrrolidone (PVP, on gold nanoparticles (AuNPs and their influence on equine platelet activation and release of particular growth factors. The gold nanoparticles were produced by chemical reduction of chloroauric acid. UV-Vis spectroscopy confirmed the presence of gold nanoparticles in investigated solutions. The AuNPs were incubated with whole blood at various concentrations. The morphology of platelets in PRP prepared from the blood incubated with AuNPs was characterized by scanning transmission electron microscopy, whereas the concentrations of growth factors and cytokines were evaluated by ELISA assays. The most promising results were obtained with equine platelets incubated with 5% AuNPs stabilized by PEI, which lead to secretion of bone morphogenetic protein 2 (BMP-2, vascular endothelial growth factor (VEGF, and fibroblast growth factor 1 (FGF-1 and simultaneously cause decrease in concentration of interleukin-1 alpha (IL-1α. The qRT-PCR confirmed ELISA test results. The incubation with 5% AuNPs stabilized by PEI leads to upregulation of BMP-2 and VEGF transcripts of mRNA level and to downregulating expression of interleukin-6 (IL-6. Obtained data shed a promising light on gold nanoparticle application for future regenerative medicine application.

  12. Electric Field Simulation and Effect of Different Solvent Ratios on the Performance of Single Electrospun PVDF/PEI Composite Film

    Directory of Open Access Journals (Sweden)

    Jin-gang Jiang

    2016-01-01

    Full Text Available On the basis of the finite element calculation theory of electric field, the electric field distribution in a representative electrospinning device is computed. The electric field structure of a needle-plate type electrospinning device was simulated by means of ANSYS software. And the vector distribution of the nozzle on the spinneret pipe was got. For the purpose of the analysis on the influence of different solvent ratios on the performance of a single electrospun PVDF/PEI composite film, polyvinylidene fluoride and polyetherimide with a mass ratio of 8/2 were dissolved in a mixed solvent. The mixed solvent is composed of N,N-dimethylformamide and tetrahydrofuran, added in different proportions. Through the electrostatic spinning technology, PVDF/PEI composite fiber membranes were prepared. Using scanning electron microscopy (SEM, X-ray diffraction (XRD, differential scanning calorimetry (DSC, and mechanical properties testing, the effects of tetrahydrofuran on the composite microstructure, crystallinity, and mechanical properties of the PVDF/PEI composite fiber membranes are discussed.

  13. Low Molecular Weight PEI-Based Vectors via Acid-Labile Ortho Ester Linkage for Improved Gene Delivery.

    Science.gov (United States)

    Zhang, Lei; Yu, Min; Wang, Jun; Tang, Rupei; Yan, Guoqing; Yao, Weijing; Wang, Xin

    2016-08-01

    A series of novel pH-sensitive gene delivery vectors (POEI 1, 2, and 3) are synthesized through Michael addition from low molecular weight PEI (LMW PEI) via acid-labile ortho ester linkage with terminal acrylates (OEAc) by various feed molar ratios. The obtained POEI 1 and POEI 2 can efficiently condense plasmid DNA into nanoparticles with size range of 200-300 nm and zeta-potentials of about +15 mV while protecting DNA from enzymatic digestion compared with POEI 3. Significantly, ortho ester groups of POEI main-chains can make an instantaneous degradation-response to acidic endosomal pH (≈5.0), resulting in accelerated disruption of polyplexes and intracellular DNA release. MTT assay reveals that all POEIs exhibit much lower cytotoxicity in different cells than branched PEI (25 KDa). As expected, POEI 1 and POEI 2 perform improved gene transfection in vitro, suggesting that such polycations might be promising gene vectors based on overcoming toxicity-efficiency contradiction.

  14. Amperometric Immunosensor for Carbofuran Detection Based on MWCNTs/GS-PEI-Au and AuNPs-Antibody Conjugate

    Directory of Open Access Journals (Sweden)

    Xiangyou Wang

    2013-04-01

    Full Text Available In this paper, an amperometric immunosensor for the detection of carbofuran was developed. Firstly, multiwall carbon nanotubes (MWCNTs and graphene sheets-ethyleneimine polymer-Au (GS-PEI-Au nanocomposites were modified onto the surface of a glass carbon electrode (GCE via self-assembly. The nanocomposites can increase the surface area of the GCE to capture a large amount of antibody, as well as produce a synergistic effect in the electrochemical performance. Then the modified electrode was coated with gold nanoparticles-antibody conjugate (AuNPs-Ab and blocked with BSA. The monoclonal antibody against carbofuran was covalently immobilized on the AuNPs with glutathione as a spacer arm. The morphologies of the GS-PEI-Au nanocomposites and the fabrication process of the immunosensor were characterized by X-ray diffraction (XRD, ultraviolet and visible absorption spectroscopy (UV-vis and scanning electron microscopy (SEM, respectively. Under optimal conditions, the immunosensor showed a wide linear range, from 0.5 to 500 ng/mL, with a detection limit of 0.03 ng/mL (S/N = 3. The as-constructed immunosensor exhibited notable performance features such as high specificity, good reproducibility, acceptable stability and regeneration performance. The results are mainly due to the excellent properties of MWCNTs, GS-PEI-Au nanocomposites and the covalent immobilization of Ab with free hapten binding sites for further immunoreaction. It provides a new avenue for amperometric immunosensor fabrication.

  15. Amperometric immunosensor for carbofuran detection based on MWCNTs/GS-PEI-Au and AuNPs-antibody conjugate.

    Science.gov (United States)

    Zhu, Ying; Cao, Yaoyao; Sun, Xia; Wang, Xiangyou

    2013-04-19

    In this paper, an amperometric immunosensor for the detection of carbofuran was developed. Firstly, multiwall carbon nanotubes (MWCNTs) and graphene sheets-ethyleneimine polymer-Au (GS-PEI-Au) nanocomposites were modified onto the surface of a glass carbon electrode (GCE) via self-assembly. The nanocomposites can increase the surface area of the GCE to capture a large amount of antibody, as well as produce a synergistic effect in the electrochemical performance. Then the modified electrode was coated with gold nanoparticles-antibody conjugate (AuNPs-Ab) and blocked with BSA. The monoclonal antibody against carbofuran was covalently immobilized on the AuNPs with glutathione as a spacer arm. The morphologies of the GS-PEI-Au nanocomposites and the fabrication process of the immunosensor were characterized by X-ray diffraction (XRD), ultraviolet and visible absorption spectroscopy (UV-vis) and scanning electron microscopy (SEM), respectively. Under optimal conditions, the immunosensor showed a wide linear range, from 0.5 to 500 ng/mL, with a detection limit of 0.03 ng/mL (S/N = 3). The as-constructed immunosensor exhibited notable performance features such as high specificity, good reproducibility, acceptable stability and regeneration performance. The results are mainly due to the excellent properties of MWCNTs, GS-PEI-Au nanocomposites and the covalent immobilization of Ab with free hapten binding sites for further immunoreaction. It provides a new avenue for amperometric immunosensor fabrication.

  16. Termination and hydration of forsteritic olivine (0 1 0) surface

    Science.gov (United States)

    Yan, Hongping; Park, Changyong; Ahn, Gun; Hong, Seungbum; Keane, Denis T.; Kenney-Benson, Curtis; Chow, Paul; Xiao, Yuming; Shen, Guoyin

    2014-11-01

    Termination and hydration of the forsteritic (Fo90Fa10) olivine (0 1 0) surface have been investigated with high-resolution specular X-ray reflectivity and Atomic Force Microscopy. The surface was prepared by polishing a naturally grown {0 1 0} face, from which we found the polished surface in acidic (pH 3.5) alumina suspension exhibits regular steps while the basic (pH 9.5) silica polished surface is irregularly roughened, indicating there are two distinguishable mechanochemical processes for the surface dissolution. The quantitative interpretation of the regular steps from the alumina-polished surface suggests that the observed step heights correspond to multiples of crystallographic unit cell. Only this atomically terraced surface is investigated with the high-resolution X-ray reflectivity (HRXR) to determine the surface termination and hydration. The basic silica paste polished surface turned out too rough to measure with X-ray reflectivity. HRXR reveals that the alumina polished olivine (0 1 0) surface in pure water is terminated at a plane including half-occupied metal ion sites (M1), an oxygen vacancy site, and a silicate tetrahedral unit with one of its apices pointing outward with respect to the surface. An ideal termination with the oxygen vacancy would fulfill the stoichiometry of the formula unit; however, in the observation, the vacancy site is filled by an adsorbed water species and about a quarter of the remaining metal ions are further depleted. The terminating plane generates two distinct atomic layers in the laterally averaged electron density profile, on which two highly ordered adsorbed water layers are formed. The first layer formation is likely through the direct interaction with the M1 plane and the second layer is likely through the hydrogen bonding interaction with the first water layer. With this multilayered adsorbed water structure, the surface metal ion is partially hydrated by the vacancy-filling water species and adsorbed water

  17. Combined Studies of ODP log Data and Seismic Reflection Data at Southern Hydrate Ridge

    Science.gov (United States)

    Papenberg, C. A.; Petersen, J.; Klaeschen, D.

    2003-12-01

    In August 2002 Ocean Drilling Program (ODP) Leg 204 (Hydrate Ridge) provided essential borehole data to complement recent seismic studies at Hydrate Ridge to correlate amplitude analysis investigations and to constrain previous results. Seismic data was acquired during cruise SO-150 in September 2000 on the German RV SONNE, aiming at qualitative and quantitative estimates of free gas and gas hydrates within the sediments across Hydrate Ridge. Hydrate Ridge is part of the accretionary complex and is characterized by the presence of extensive gas hydrates, causing a prominent Bottom Simulating Reflector (BSR) in marine seismic records. Several seismic in- and crosslines were shot across the ridge to map the spatial distribution of the BSR. Wide angle reflection data of narrowly spaced Ocean Bottom Seismometers (OBS) allow frequency dependent amplitude variations with offset (AVO) investigations. Seismic reflection data, recorded simultaneously with a single channel surface and deep tow streamer completed the data set. The usage of different sources during acquisition provided additional information of the frequency response of the BSR signature. This data set was used to study the complex seismic behaviour of such gas hydrate environments in detail. The borehole data, collected during ODP Leg 204, now improve recent seismic investigations and support previous results. Within the COLIBRI project log information (Vp, Vs and density) was used for forward modeling to combine seismic investigations with new borehole data. The P wave velocity model of a traveltime inversion and AVO analysis of the seismic OBS sections suggest rather low quantities of gas hydrate or at least the lack of massive hydrate zones. Shear wave phases, identified in the seismic OBS sections, refer to slow S wave velocities in the upper sediment layers above the BSR, which support a model with small amounts of hydrate or patchy hydrate zones within the upper sediments.

  18. Clinker mineral hydration at reduced relative humidities

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede; Hansen, Per Freiesleben; Lachowski, Eric E.;

    1999-01-01

    Vapour phase hydration of purl cement clinker minerals at reduced relative humidities is described. This is relevant to modern high performance concrete that may self-desiccate during hydration and is also relevant to the quality of the cement during storage. Both the oretical considerations...... and experimental data are presented showing that C(3)A can hydrate at lower humidities than either C3S or C2S. It is suggested that the initiation of hydration during exposure to water vapour is nucleation controlled. When C(3)A hydrates at low humidity, the characteristic hydration product is C(3)AH(6...

  19. Progress of Gas Hydrate Studies in China

    Institute of Scientific and Technical Information of China (English)

    樊栓狮; 汪集旸

    2006-01-01

    A brief overview is given on the gas hydrate-related research activities carried out by Chinese researchers in the past 15 years. The content involves: (1) Historical review. Introducing the gas hydrate research history in China; (2) Gas hydrate research groups in China. There are nearly 20 groups engaged in gas hydrate research now; (3) Present studies.Including fundamental studies, status of the exploration of natural gas hydrate resources in the South China Sea region, and development of hydrate-based new techniques; (4) Future development.

  20. Layer-by-layer assembled multilayers of polyethylenimine-stabilized platinum nanoparticles and PEDOT:PSS as anodes for the methanol oxidation reaction.

    Science.gov (United States)

    Knowles, Kyler R; Hanson, Colin C; Fogel, April L; Warhol, Brian; Rider, David A

    2012-07-25

    Polyethylenimine-capped platinum nanoparticles (PEI-capped Pt NPs) are synthesized by photoreduction and qualified as a component for electrostatic layer-by-layer assembly and subsequent electrocatalysis. The PEI-capped Pt NPs are characterized for size and charge using scanning force microscopy, transmission electron microscopy, dynamic light scattering and zetapotential. Well-defined multilayers are produced via thin film electrostatic assembly of PEI-capped Pt NPs with the conducting polymer: poly(3,4-ethylenedioxythiophene):poly(p-styrenesulfonate) [(PEDOT:PSS)(-)Na(+)]. The composite thin films are subsequently characterized by ultraviolet-visible spectroscopy, scanning force microscopy, inductively coupled plasma mass spectroscopy and thermogravimetric analysis. The layer-by-layer deposition process was found to proceed in a controlled manner which permits the fabrication of stable and uniform multilayer thin films. [PEI-capped Pt NPs/(PEDOT:PSS)] multilayers were found to be an active catalyst coating for the oxidation of methanol and a 20 bilayer film proceeds with a stable level of catalyst activity for over 1000 oxidation cycles.

  1. Hydration of fly ash cement

    Energy Technology Data Exchange (ETDEWEB)

    Etsuo Sakai; Shigeyoshi Miyahara; Shigenari Ohsawa; Seung-Heun Lee; Masaki Daimon [Tokyo Institute of Technology, Tokyo (Japan). Department of Metallurgy and Ceramics Science, Graduate School of Science and Engineering

    2005-06-01

    It is necessary to establish the material design system for the utilization of large amounts of fly ash as blended cement instead of disposing of it as a waste. Cement blended with fly ash is also required as a countermeasure to reduce the amount of CO{sub 2} generation. In this study, the influences of the glass content and the basicity of glass phase on the hydration of fly ash cement were clarified and hydration over a long curing time was characterized. Two kinds of fly ash with different glass content, one with 38.2% and another with 76.6%, were used. The hydration ratio of fly ash was increased by increasing the glass content in fly ash in the specimens cured for 270 days. When the glass content of fly ash is low, the basicity of glass phase tends to decrease. Reactivity of fly ash is controlled by the basicity of the glass phase in fly ash during a period from 28 to 270 days. However, at an age of 360 days, the reaction ratios of fly ash show almost identical values with different glass contents. Fly ash also affected the hydration of cement clinker minerals in fly ash cement. While the hydration of alite was accelerated, that of belite was retarded at a late stage.

  2. Formation and characterization of β-cyclodextrin (β-CD) - polyethyleneglycol (PEG) - polyethyleneimine (PEI) coated Fe3O4 nanoparticles for loading and releasing 5-Fluorouracil drug.

    Science.gov (United States)

    Prabha, G; Raj, V

    2016-05-01

    In this work, β-cyclodextrin (β-CD) - polyethyleneglycol (PEG) - polyethyleneimine (PEI) coated iron oxide nanoparticles (Fe3O4-β-CD-PEG-PEI) were developed as drug carriers for drug delivery applications. The 5- Fluorouracil (5-FU) was chosen as model drug molecule. The developed nanoparticles (Fe3O4-β-CD-PEG-PEI) were characterized by various techniques such as Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM). The average particles size range of 5-FU loaded Fe3O4-β-CD, Fe3O4-β-CD-PEG and Fe3O4-β-CD-PEG-PEI nanoparticles were from 151 to 300nm and zeta potential value of nanoparticles were from -43mV to -20mV as measured using Malvern Zetasizer. Finally, encapsulation efficiency (EE), loading capacity (LC) and in-vitro drug release performance of 5-FU drug loaded Fe3O4-β-CD, Fe3O4-β-CD-PEG and Fe3O4-β-CD-PEG-PEI nanoparticles was evaluated by UV-vis spectroscopy. In-vitro cytotoxicity tests investigated by MTT assay indicate that 5-FU loaded Fe3O4-β-CD-PEG-PEI nanoparticles were toxic to cancer cells and non-toxic to normal cells. The in-vitro release behavior of 5-FU from drug (5-FU) loaded Fe3O4-β-CD-PEG-PEI composite at different pH values and temperature was studied. It was found that 5-FU was released faster in pH 6.8 than in the acidic mediums (pH 1.2), and the released quantity was higher. Therefore, the newly prepared Fe3O4-β-CD-PEG-PEI carrier exhibits a promising potential capability for anticancer drug delivery in tumor therapy.

  3. Water dynamics in protein hydration shells: the molecular origins of the dynamical perturbation.

    Science.gov (United States)

    Fogarty, Aoife C; Laage, Damien

    2014-07-17

    Protein hydration shell dynamics play an important role in biochemical processes including protein folding, enzyme function, and molecular recognition. We present here a comparison of the reorientation dynamics of individual water molecules within the hydration shell of a series of globular proteins: acetylcholinesterase, subtilisin Carlsberg, lysozyme, and ubiquitin. Molecular dynamics simulations and analytical models are used to access site-resolved information on hydration shell dynamics and to elucidate the molecular origins of the dynamical perturbation of hydration shell water relative to bulk water. We show that all four proteins have very similar hydration shell dynamics, despite their wide range of sizes and functions, and differing secondary structures. We demonstrate that this arises from the similar local surface topology and surface chemical composition of the four proteins, and that such local factors alone are sufficient to rationalize the hydration shell dynamics. We propose that these conclusions can be generalized to a wide range of globular proteins. We also show that protein conformational fluctuations induce a dynamical heterogeneity within the hydration layer. We finally address the effect of confinement on hydration shell dynamics via a site-resolved analysis and connect our results to experiments via the calculation of two-dimensional infrared spectra.

  4. Stages of Gas-Hydrate Evolution on the Northern Cascadia Margin

    Directory of Open Access Journals (Sweden)

    the IODP Expedition 311 Scientists

    2006-09-01

    Full Text Available Natural gas hydrate occurs beneath many continental slopes and in arctic permafrost areas. Recent studies have indicated that the largest deposits of gas hydrate might lie in nearly horizontal layers several hundred meters beneath the seafloor of continental slopes, especially in the large, accretionary sedimentary prisms of subduction zones. Expedition 311 of the Integrated Ocean Drilling Program (IODP investigated the formation of gas hydrate in the accretionary prism of the Cascadia subduction zone (Fig. 1. The primary objectives of Expedition 311 were to test and constraingeological models of gas hydrate formation by upward fluidand methane transport in accretionary prisms. We specifi -cally sought to (a determine the mechanisms that controlthe nature, magnitude, and distribution of the gas hydrate,(b find the pathways of the fluid migration required to formlarge concentrations of gas hydrate, (c examine the effectsof gas hydrate on the physical properties of the host sediment,and (d investigate the microbiology and geochemistryassociated with the occurrence of gas hydrate. Furthermore,we concentrated on the contrast between methane transportby focused fl ow in fault zones and by dispersed pervasiveupward flow at various scales of permeability.

  5. Submarine Slope Failure Primed and Triggered by Bottom Water Warming in Oceanic Hydrate-Bearing Deposits

    Directory of Open Access Journals (Sweden)

    Tae-Hyuk Kwon

    2012-08-01

    Full Text Available Many submarine slope failures in hydrate-bearing sedimentary deposits might be directly triggered, or at least primed, by gas hydrate dissociation. It has been reported that during the past 55 years (1955–2010 the 0–2000 m layer of oceans worldwide has been warmed by 0.09 °C because of global warming. This raises the following scientific concern: if warming of the bottom water of deep oceans continues, it would dissociate natural gas hydrates and could eventually trigger massive slope failures. The present study explored the submarine slope instability of oceanic gas hydrate-bearing deposits subjected to bottom water warming. One-dimensional coupled thermal-hydraulic-mechanical (T-H-M finite difference analyses were performed to capture the underlying physical processes initiated by bottom water warming, which includes thermal conduction through sediments, thermal dissociation of gas hydrates, excess pore pressure generation, pressure diffusion, and hydrate dissociation against depressurization. The temperature rise at the seafloor due to bottom water warming is found to create an excess pore pressure that is sufficiently large to reduce the stability of a slope in some cases. Parametric study results suggest that a slope becomes more susceptible to failure with increases in thermal diffusivity and hydrate saturation and decreases in pressure diffusivity, gas saturation, and water depth. Bottom water warming can be further explored to gain a better understanding of the past methane hydrate destabilization events on Earth, assuming that more reliable geological data is available.

  6. Sensitivity Analysis of Gas Production from Class 2 and Class 3 Hydrate Deposits

    Energy Technology Data Exchange (ETDEWEB)

    Reagan, Matthew; Moridis, George; Zhang, Keni

    2008-05-01

    Gas hydrates are solid crystalline compounds in which gas molecules are lodged within the lattices of an ice-like crystalline solid. The vast quantities of hydrocarbon gases trapped in hydrate formations in the permafrost and in deep ocean sediments may constitute a new and promising energy source. Class 2 hydrate deposits are characterized by a Hydrate-Bearing Layer (HBL) that is underlain by a saturated zone of mobile water. Class 3 hydrate deposits are characterized by an isolated Hydrate-Bearing Layer (HBL) that is not in contact with any hydrate-free zone of mobile fluids. Both classes of deposits have been shown to be good candidates for exploitation in earlier studies of gas production via vertical well designs - in this study we extend the analysis to include systems with varying porosity, anisotropy, well spacing, and the presence of permeable boundaries. For Class 2 deposits, the results show that production rate and efficiency depend strongly on formation porosity, have a mild dependence on formation anisotropy, and that tighter well spacing produces gas at higher rates over shorter time periods. For Class 3 deposits, production rates and efficiency also depend significantly on formation porosity, are impacted negatively by anisotropy, and production rates may be larger, over longer times, for well configurations that use a greater well spacing. Finally, we performed preliminary calculations to assess a worst-case scenario for permeable system boundaries, and found that the efficiency of depressurization-based production strategies are compromised by migration of fluids from outside the system.

  7. Biomimetic layer-by-layer deposition assisted synthesis of Cu, N co-doped TiO2 nanosheets with enhanced visible light photocatalytic performance.

    Science.gov (United States)

    Wang, Xiaobo; Yan, Yong; Hao, Bo; Chen, Ge

    2014-10-07

    In this paper, a Cu, N co-doped TiO2 nanosheet with increased visible light photocatalytic activity was successfully synthesized using a biomimetic layer-by-layer deposition process. The polymer, branched-polyethyleneimine (b-PEI) was used as an induction agent for the hydrolysis of titanium bis(ammonium lactato)-dihydroxide (Ti-BALDH) as well as for a nitrogen resource, and the graphene oxide (GO) was used as a two-dimensional nano-template. The positively charged b-PEI will bind to the negatively charged GO and titania. In a typical layer-by-layer deposition process, GO nanosheets are exposed in an alternating fashion to aqueous b-PEI, CuCl2 and Ti-BALDH solutions, thus, making the layer-by-layer deposition of a conformal b-PEI/Cu-Ti-O coating on the GO. Subsequent b-PEI and GO pyrolysis at 550 °C under air yielded Cu, N co-doped TiO2 nanosheets. The materials obtained were comprehensively investigated by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, Raman spectra, photoluminescence spectra and electron paramagnetic resonance. The Cu, N co-doped TiO2 nanosheets showed obviously enhanced photocatalytic activity which was evaluated by degradation of methylene blue under visible light irradiation. This research might provide some new insights for the "green synthesis" of the simultaneous doping of two kinds of foreign atoms into TiO2 with controlled morphology and photocatalytic properties.

  8. Comparison of stromal hydration techniques for clear corneal cataract incisions: conventional hydration versus anterior stromal pocket hydration.

    Science.gov (United States)

    Mifflin, Mark D; Kinard, Krista; Neuffer, Marcus C

    2012-06-01

    Anterior stromal pocket hydration was compared with conventional hydration for preventing wound leak after 2.8 mm uniplanar clear corneal incisions (CCIs) in patients having routine cataract surgery. Conventional hydration involves hydration of the lateral walls of the main incision with visible whitening of the stroma. The anterior stromal pocket hydration technique involves creation of an additional supraincisional stromal pocket overlying the main incision, which is then hydrated instead of the main incision. Sixty-six eyes of 48 patients were included in the data analysis with 33 assigned to each study group. The anterior stromal pocket hydration technique was significantly better than conventional hydration in preventing wound leak due to direct pressure on the posterior lip of the incision. Copyright © 2012 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

  9. PEI-engineered respirable particles delivering a decoy oligonucleotide to NF-κB: inhibiting MUC2 expression in LPS-stimulated airway epithelial cells.

    Directory of Open Access Journals (Sweden)

    Francesca Ungaro

    Full Text Available A specific and promising approach to limit inflammation and mucin iperproduction in chronic lung diseases relies on specific inhibition of nuclear Factor-κB (NF-κB by a decoy oligonucleotide (dec-ODN. To fulfill the requirements dictated by translation of dec-ODN therapy in humans, inhalable dry powders were designed on a rational basis to provide drug protection, sustained release and to optimize pharmacological response. To this end, large porous particles (LPP for dec-ODN delivery made of a sustained release biomaterial (poly(lactic-co-glycolic acid, PLGA and an "adjuvant" hydrophilic polymer (polyethylenimine, PEI were developed and their effects on LPS-stimulated human airway epithelial cells evaluated. The composite PLGA/PEI particles containing dec-ODN (i.e., LPP(PEI were successfully engineered for widespread deposition in the lung and prolonged release of intact dec-ODN in vitro. LPP(PEI caused a prolonged inhibition of IL-8 and MUC2 expression in CF human bronchial epithelial cells and human epithelial pulmonary NCI-H292 cells, respectively, as compared to naked dec-ODN. Nonetheless, as compared to previously developed LPP, the presence of PEI was essential to construct a dec-ODN delivery system able to act in mucoepidermoid lung epithelial cells. In perspective, engineering LPP with PEI may become a key factor for tuning carrier properties, controlling lung inflammation and mucin production which, in turn, can foster in vivo translation of dec-ODN therapy.

  10. The strength and rheology of methane clathrate hydrate

    Science.gov (United States)

    Durham, W.B.; Kirby, S.H.; Stern, L.A.; Zhang, W.

    2003-01-01

    Methane clathrate hydrate (structure I) is found to be very strong, based on laboratory triaxial deformation experiments we have carried out on samples of synthetic, high-purity, polycrystalline material. Samples were deformed in compressional creep tests (i.e., constant applied stress, ??), at conditions of confining pressure P = 50 and 100 MPa, strain rate 4.5 ?? 10-8 ??? ?? ??? 4.3 ?? 10-4 s-1, temperature 260 ??? T ??? 287 K, and internal methane pressure 10 ??? PCH4 ??? 15 MPa. At steady state, typically reached in a few percent strain, methane hydrate exhibited strength that was far higher than expected on the basis of published work. In terms of the standard high-temperature creep law, ?? = A??ne-(E*+PV*)/RT the rheology is described by the constants A = 108.55 MPa-n s-1, n = 2.2, E* = 90,000 J mol-1, and V* = 19 cm3 mol-1. For comparison at temperatures just below the ice point, methane hydrate at a given strain rate is over 20 times stronger than ice, and the contrast increases at lower temperatures. The possible occurrence of syntectonic dissociation of methane hydrate to methane plus free water in these experiments suggests that the high strength measured here may be only a lower bound. On Earth, high strength in hydrate-bearing formations implies higher energy release upon decomposition and subsequent failure. In the outer solar system, if Titan has a 100-km-thick near-surface layer of high-strength, low-thermal conductivity methane hydrate as has been suggested, its interior is likely to be considerably warmer than previously expected.

  11. Water diffusion in fully hydrated porcine stratum corneum

    Energy Technology Data Exchange (ETDEWEB)

    Pieper, J.; Charalambopoulou, G.; Steriotis, Th.; Vasenkov, S.; Desmedt, A.; Lechner, R.E

    2003-08-01

    The microscopic mechanisms of water diffusion in fully hydrated porcine stratum corneum (SC) have been studied by a combination of incoherent quasielastic neutron scattering (QENS) and pulsed field gradient-nuclear magnetic resonance (PFG-NMR) for two sample orientations. The presence of three types of water in fully hydrated SC is inferred on the basis of water sorption isotherm data, i.e., (a) bound and (b) weakly bound hydration water forming layers between adjacent lipid bilayers of SC, as well as (c) bulk water probably located in the corneocytes and in intercellular regions. Water self-diffusion coefficients for motions parallel and perpendicular to the membrane plane of D{sub parallel}=3.30x10{sup -10} m{sup 2}/s and D{sub perpendicular}=1.56x10{sup -10} m{sup 2}/s, respectively, were determined by PFG-NMR and assigned to the translational diffusion of weakly bound water. QENS measurements have been carried out using different samples hydrated with H{sub 2}O and D{sub 2}O, respectively, in order to separate the contribution of SC from that of the water. The QENS data for both sample orientations and two different energy resolutions can be fitted by a model which accounts for the microscopic dynamics of all three aforementioned types of water. This analysis establishes rotational diffusion coefficients for bound and weakly bound hydration water of 0.025 and 0.030 meV, respectively. Furthermore, the QENS data prove the presence of bulk water in fully hydrated SC samples.

  12. Gas hydrates forming and decomposition conditions analysis

    Directory of Open Access Journals (Sweden)

    А. М. Павленко

    2017-07-01

    Full Text Available The concept of gas hydrates has been defined; their brief description has been given; factors that affect the formation and decomposition of the hydrates have been reported; their distribution, structure and thermodynamic conditions determining the gas hydrates formation disposition in gas pipelines have been considered. Advantages and disadvantages of the known methods for removing gas hydrate plugs in the pipeline have been analyzed, the necessity of their further studies has been proved. In addition to the negative impact on the process of gas extraction, the hydrates properties make it possible to outline the following possible fields of their industrial use: obtaining ultrahigh pressures in confined spaces at the hydrate decomposition; separating hydrocarbon mixtures by successive transfer of individual components through the hydrate given the mode; obtaining cold due to heat absorption at the hydrate decomposition; elimination of the open gas fountain by means of hydrate plugs in the bore hole of the gushing gasser; seawater desalination, based on the hydrate ability to only bind water molecules into the solid state; wastewater purification; gas storage in the hydrate state; dispersion of high temperature fog and clouds by means of hydrates; water-hydrates emulsion injection into the productive strata to raise the oil recovery factor; obtaining cold in the gas processing to cool the gas, etc.

  13. Numerical studies of depressurization-induced gas production from an interbedded marine turbidite gas hydrate reservoir model

    Science.gov (United States)

    Myshakin, Evgeniy; Lin, Jeen-Shang; Uchida, Shun; Seol, Yongkoo; Collett, Timothy S.; Boswell, Ray

    2017-01-01

    The numerical simulation of thin hydrate-bearing sand layers interbedded with mud layers is investigated. In this model, the lowest hydrate layer occurs at the base of gas hydrate stability and overlies a thinly-interbedded saline aquifer. The predicted gas rates reach 6.25 MMscf/day (1.77 x 105 m3 /day) after 90 days of continuous depressurization with manageable water production. Development of horizontal dissociating interfaces between hydrate-bearing sand and mud layers is a primary determinant of reservoir performance. A set of simulations has been executed to assess uncertainty in in situ permeability and to determine the impact of the saline aquifer on productivity.

  14. Developmental and reproductive toxicity of PVP/PEI-coated silver nanoparticles to zebrafish.

    Science.gov (United States)

    Orbea, Amaia; González-Soto, Nagore; Lacave, José María; Barrio, Irantzu; Cajaraville, Miren P

    2017-09-01

    Cellular and molecular mechanisms of toxicity of silver nanoparticles (NPs) and their toxicity to fish embryos after waterborne exposure have been widely investigated, but much less information is available regarding the effect of Ag NPs on physiological functions such as growth or reproduction. In this work, the effects of waterborne exposure of adult zebrafish (Danio rerio) to PVP/PEI coated Ag NPs (~5nm) on reproduction (fecundity) were investigated. Moreover, the development of the embryos after parental exposure was compared with the development of embryos after direct waterborne exposure to the NPs. For this, two experiments were run: 1) embryos from unexposed parents were treated for 5days with Ag NPs (10μgAgL(-1)-10mgAgL(-1)) and development was monitored, and 2) selected breeding zebrafish were exposed for 3weeks to 100ngAgL(-1) (environmentally relevant concentration) or to 10μgAgL(-1) of Ag NPs, fecundity was scored and development of resulting embryos was monitored up to 5days. Waterborne exposure of embryos to Ag NPs resulted in being highly toxic (LC50 at 120h=50μgAgL(-1)), causing 100% mortality during the first 24h of exposure at 0.1mgAgL(-1). Exposure of adults, even at the environmentally relevant silver concentration, caused a significant reduction of fecundity by the second week of treatment and resulting embryos showed a higher prevalence of malformations than control embryos. Exposed adult females presented higher prevalence of vacuolization in the liver. These results show that Ag NPs at an environmentally relevant concentration are able to affect population level parameters in zebrafish. Copyright © 2017 Elsevier Inc. All rights reserved.

  15. Screening and characterization of ethanol-tolerant and thermotolerant acetic acid bacteria from Chinese vinegar Pei.

    Science.gov (United States)

    Chen, Yang; Bai, Ye; Li, Dongsheng; Wang, Chao; Xu, Ning; Hu, Yong

    2016-01-01

    Acetic acid bacteria (AAB) are important microorganisms in the vinegar industry. However, AAB have to tolerate the presence of ethanol and high temperatures, especially in submerged fermentation (SF), which inhibits AAB growth and acid yield. In this study, seven AAB that are tolerant to temperatures above 40 °C and ethanol concentrations above 10% (v/v) were isolated from Chinese vinegar Pei. All the isolated AAB belong to Acetobacter pasteurianus according to 16S rDNA analysis. Among all AAB, AAB4 produced the highest acid yield under high temperature and ethanol test conditions. At 4% ethanol and 30-40 °C temperatures, AAB4 maintained an alcohol-acid transform ratio of more than 90.5 %. High alcohol-acid transform ratio was still maintained even at higher temperatures, namely, 87.2, 77.1, 14.5 and 2.9% at 41, 42, 43 and 44 °C, respectively. At 30 °C and different initial ethanol concentrations (4-10%), the acid yield by AAB4 increased gradually, although the alcohol-acid transform ratio decreased to some extent. However, 46.5, 8.7 and 0.9% ratios were retained at ethanol concentrations of 11, 12 and 13%, respectively. When compared with AS1.41 (an AAB widely used in China) using a 10 L fermentor, AAB4 produced 42.0 g/L acetic acid at 37 °C with 10% ethanol, whereas AS1.41 almost stopped producing acetic acid. In conclusion, these traits suggest that AAB4 is a valuable strain for vinegar production in SF.

  16. Hydration of highly charged ions.

    Science.gov (United States)

    Hofer, Thomas S; Weiss, Alexander K H; Randolf, Bernhard R; Rode, Bernd M

    2011-08-01

    Based on a series of ab initio quantum mechanical charge field molecular dynamics (QMCF MD) simulations, the broad spectrum of structural and dynamical properties of hydrates of trivalent and tetravalent ions is presented, ranging from extreme inertness to immediate hydrolysis. Main group and transition metal ions representative for different parts of the periodic system are treated, as are 2 threefold negatively charged anions. The results show that simple predictions of the properties of the hydrates appear impossible and that an accurate quantum mechanical simulation in cooperation with sophisticated experimental investigations seems the only way to obtain conclusive results.

  17. Great Market Potential of Hydrazine Hydrate

    Institute of Scientific and Technical Information of China (English)

    Shi Yuying

    2007-01-01

    @@ Stable consumption growth worldwide Hydrazine hydrate is an organic chemical raw material with extensive applications. The world's capacity to produce hydrazine hydrate has reached more than 200 thousand t/atoday (based on 100% hydrazine content).

  18. Methods to determine hydration states of minerals and cement hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Baquerizo, Luis G., E-mail: luis.baquerizoibarra@holcim.com [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Matschei, Thomas [Innovation, Holcim Technology Ltd., CH-5113 Holderbank (Switzerland); Scrivener, Karen L. [Laboratory of Construction Materials, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne (Switzerland); Saeidpour, Mahsa; Thorell, Alva; Wadsö, Lars [Building Materials, Lund University, Box 124, 221 000 Lund (Sweden)

    2014-11-15

    This paper describes a novel approach to the quantitative investigation of the impact of varying relative humidity (RH) and temperature on the structure and thermodynamic properties of salts and crystalline cement hydrates in different hydration states (i.e. varying molar water contents). The multi-method approach developed here is capable of deriving physico-chemical boundary conditions and the thermodynamic properties of hydrated phases, many of which are currently missing from or insufficiently reported in the literature. As an example the approach was applied to monosulfoaluminate, a phase typically found in hydrated cement pastes. New data on the dehydration and rehydration of monosulfoaluminate are presented. Some of the methods used were validated with the system Na{sub 2}SO{sub 4}–H{sub 2}O and new data related to the absorption of water by anhydrous sodium sulfate are presented. The methodology and data reported here should permit better modeling of the volume stability of cementitious systems exposed to various different climatic conditions.

  19. Novel understanding of calcium silicate hydrate from dilute hydration

    KAUST Repository

    Zhang, Lina

    2017-05-13

    The perspective of calcium silicate hydrate (C-S-H) is still confronting various debates due to its intrinsic complicated structure and properties after decades of studies. In this study, hydration at dilute suspension of w/s equaling to 10 was conducted for tricalcium silicate (C3S) to interpret long-term hydration process and investigate the formation, structure and properties of C-S-H. Based on results from XRD, IR, SEM, NMR and so forth, loose and dense clusters of C-S-H with analogous C/S ratio were obtained along with the corresponding chemical formulae proposed as Ca5Si4O13∙6.2H2O. Crystalline structure inside C-S-H was observed by TEM, which was allocated at the foil-like proportion as well as the edge of wrinkles of the product. The long-term hydration process of C3S in dilute suspension could be sketchily described as migration of calcium hydroxide and in-situ growth of C-S-H with equilibrium silicon in aqueous solution relatively constant and calcium varied.

  20. Molecular Dynamics Modeling of Hydrated Calcium-Silicate-Hydrate (CSH) Cement Molecular Structure

    Science.gov (United States)

    2014-08-30

    properties of key hydrated cement constituent calcium-silicate-hydrate (CSH) at the molecular, nanometer scale level. Due to complexity, still unknown...public release; distribution is unlimited. Molecular Dynamics Modeling of Hydrated Calcium-Silicate- Hydrate (CSH) Cement Molecular Structure The views... Cement Molecular Structure Report Title Multi-scale modeling of complex material systems requires starting from fundamental building blocks to

  1. Hydration and Thermal Expansion in Anatase Nanoparticles.

    Science.gov (United States)

    Zhu, He; Li, Qiang; Ren, Yang; Fan, Longlong; Chen, Jun; Deng, Jinxia; Xing, Xianran

    2016-08-01

    A tunable thermal expansion is reported in nanosized anatase by taking advantage of surface hydration. The coefficient of thermal expansion of 4 nm TiO2 along a-axis is negative with a hydrated surface and is positive without a hydrated surface. High-energy synchrotron X-ray pair distribution function analysis combined with ab initio calculations on the specific hydrated surface are carried out to reveal the local structure distortion that is responsible for the unusual negative thermal expansion.

  2. Hydration and Thermal Expansion in Anatase Nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, He [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Li, Qiang [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Ren, Yang [Argonne National Laboratory, X-Ray Science Division, Argonne IL 60439 USA; Fan, Longlong [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Chen, Jun [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Deng, Jinxia [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China; Xing, Xianran [Department of Physical Chemistry, University of Science and Technology Beijing, Beijing 100083 China

    2016-06-06

    A tunable thermal expansion is reported in nanosized anatase by taking advantage of surface hydration. The coefficient of thermal expansion of 4 nm TiO2 along a-axis is negative with a hydrated surface and is positive without a hydrated surface. High-energy synchrotron X-ray pair distribution function analysis combined with ab initio calculations on the specific hydrated surface are carried out to reveal the local structure distortion that is responsible for the unusual negative thermal expansion.

  3. [PHEMA/PEI]–Cu(II) based immobilized metal affinity chromatography cryogels: Application on the separation of IgG from human plasma

    Energy Technology Data Exchange (ETDEWEB)

    Bakhshpour, Monireh; Derazshamshir, Ali; Bereli, Nilay [Department of Chemistry, Biochemistry Division, Hacettepe University, Ankara (Turkey); Elkak, Assem [Laboratory of “Valorisation des Ressources Naturelles et Produits de Santé (VRNPS)”, Doctoral School of Sciences and Technology, Lebanese University, Rafic Hariri University Campus, Hadath (Lebanon); Denizli, Adil, E-mail: denizli@hacettepe.edu [Department of Chemistry, Biochemistry Division, Hacettepe University, Ankara (Turkey)

    2016-04-01

    The immobilized metal-affinity chromatography (IMAC) has gained significant interest as a widespread separation and purification tool for therapeutic proteins, nucleic acids and other biological molecules. The enormous potential of IMAC for proteins with natural surface exposed-histidine residues and for recombinant proteins with histidine clusters. Cryogels as monolithic materials have recently been proposed as promising chromatographic adsorbents for the separation of biomolecules in downstream processing. In the present study, IMAC cryogels have been synthesized and utilized for the adsorption and separation of immunoglobulin G (IgG) from IgG solution and whole human plasma. For this purpose, Cu(II)-ions were coupled to poly(hydroxyethyl methacrylate) PHEMA using poly(ethylene imine) (PEI) as the chelating ligand. In this study the cryogels formation optimized by the varied proportion of PEI from 1% to 15% along with different amounts of Cu (II) as chelating metal. The prepared cryogels were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The [PHEMA/PEI]–Cu(II) cryogels were assayed for their capability to bind the human IgG from aqueous solutions. The IMAC cryogels were found to have high affinity toward human IgG. The adsorption of human IgG was investigated onto the PHEMA/PEI cryogels with (10% PEI) and the concentration of Cu (II) varied as 10, 50, 100 and 150 mg/L. The separation of human IgG was achieved in one purification step at pH 7.4. The maximum adsorption capacity was observed at the [PHEMA/PEI]–Cu(II) (10% PEI) with 72.28 mg/g of human IgG. The purification efficiency and human IgG purity were investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). - Highlights: • Cu(II)-ions were coupled to PHEMA using PEI as the chelating ligand. • Cu(II) chelated [PHEMA/PEI] cryogels for IgG separation were produced. • Maximum IgG adsorption capacity

  4. Hydration of swelling clays: multi-scale sequence of hydration and determination of macroscopic energies from microscopic properties; Hydratation des argiles gonflantes: sequence d'hydratation multi-echelle determination des energies macroscopiques a partir des proprietes microscopiques

    Energy Technology Data Exchange (ETDEWEB)

    Salles, F

    2006-10-15

    Smectites have interesting properties which make them potential candidates for engineered barriers in deep geological nuclear waste repository: low permeability, swelling and cations retention. The subject of this thesis consists in the determination of the relationship between hydration properties, swelling properties and cations mobility in relation with confinement properties of clayey materials. The aim is to understand and to predict the behaviour of water in smectites, following two research orientations: the mechanistic aspects and the energetic aspects of the hydration of smectites. We worked on the Na-Ca montmorillonite contained in the MX80 bentonite, with the exchanged homo ionic structure (saturated with alkaline cations and calcium cations). The approach crosses the various scales (microscopic, mesoscopic and macroscopic) and implied the study of the various components of the system (layer-cation-water), by using original experimental methods (thermo-poro-metry and electric conductivity for various relative humidities (RH) and electrostatic calculations. Initially, the dry state is defined by SCTA (scanning calorimetry thermal analysis). Then a classical characterization of the smectite porosity for the dry state is carried out using mercury intrusion and nitrogen adsorption. We evidenced the existence of a meso-porosity which radius varies from 2 to 10 nm depending on the compensating cation. The thermo-poro-metry and conductivity experiments performed at various hydration states made it possible to follow the increase in the pore sizes and the cations mobility as a function of the hydration state. We highlight in particular the existence of an osmotic mesoscopic swelling for low RH (approximately 50-60%RH for Li and Na). By combining the results of thermo-poro-metry, X-ray diffraction and electric conductivity, we are able to propose a complete hydration sequence for each cation, showing the crucial role of the compensating cation in the hydration of

  5. Hofmeister effects: interplay of hydration, nonelectrostatic potentials, and ion size.

    Science.gov (United States)

    Parsons, Drew F; Boström, Mathias; Lo Nostro, Pierandrea; Ninham, Barry W

    2011-07-21

    The classical Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloids, and corresponding theories of electrolytes, are unable to explain ion specific forces between colloidal particles quantitatively. The same is true generally, for surfactant aggregates, lipids, proteins, for zeta and membrane potentials and in adsorption phenomena. Even with fitting parameters the theory is not predictive. The classical theories of interactions begin with continuum solvent electrostatic (double layer) forces. Extensions to include surface hydration are taken care of with concepts like inner and outer Helmholtz planes, and "dressed" ion sizes. The opposing quantum mechanical attractive forces (variously termed van der Waals, Hamaker, Lifshitz, dispersion, nonelectrostatic forces) are treated separately from electrostatic forces. The ansatz that separates electrostatic and quantum forces can be shown to be thermodynamically inconsistent. Hofmeister or specific ion effects usually show up above ≈10(-2) molar salt. Parameters to accommodate these in terms of hydration and ion size had to be invoked, specific to each case. Ionic dispersion forces, between ions and solvent, for ion-ion and ion-surface interactions are not explicit in classical theories that use "effective" potentials. It can be shown that the missing ionic quantum fluctuation forces have a large role to play in specific ion effects, and in hydration. In a consistent predictive theory they have to be included at the same level as the nonlinear electrostatic forces that form the skeletal framework of standard theory. This poses a challenge. The challenges go further than academic theory and have implications for the interpretation and meaning of concepts like pH, buffers and membrane potentials, and for their experimental interpretation. In this article we overview recent quantitative developments in our evolving understanding of the theoretical origins of specific ion, or Hofmeister effects. These are demonstrated

  6. Is Obsidian Hydration Dating Affected by Relative Humidity?

    Science.gov (United States)

    Friedman, I.; Trembour, F.W.; Smith, G.I.; Smith, F.L.

    1994-01-01

    Experiments carried out under temperatures and relative humidities that approximate ambient conditions show that the rate of hydration of obsidian is a function of the relative humidity, as well as of previously established variables of temperature and obsidian chemical composition. Measurements of the relative humidity of soil at 25 sites and at depths of between 0.01 and 2 m below ground show that in most soil environments, at depths below about 0.25 m, the relative humidity is constant at 100%. We have found that the thickness of the hydrated layer developed on obsidian outcrops exposed to the sun and to relative humidities of 30-90% is similar to that formed on other portions of the outcrop that were shielded from the sun and exposed to a relative humidity of approximately 100%. Surface samples of obsidian exposed to solar heating should hydrate more rapidly than samples buried in the ground. However, the effect of the lower mean relative humidity experiences by surface samples tends to compensate for the elevated temperature, which may explain why obsidian hydration ages of surface samples usually approximate those derived from buried samples.

  7. Atomistic simulations of cation hydration in sodium and calcium montmorillonite nanopores

    Science.gov (United States)

    Yang, Guomin; Neretnieks, Ivars; Holmboe, Michael

    2017-08-01

    During the last four decades, numerous studies have been directed to the swelling smectite-rich clays in the context of high-level radioactive waste applications and waste-liners for contaminated sites. The swelling properties of clay mineral particles arise due to hydration of the interlayer cations and the diffuse double layers formed near the negatively charged montmorillonite (MMT) surfaces. To accurately study the cation hydration in the interlayer nanopores of MMT, solvent-solute and solvent-clay surface interactions (i.e., the solvation effects and the shape effects) on the atomic level should be taken into account, in contrast to many recent electric double layer based methodologies using continuum models. Therefore, in this research we employed fully atomistic simulations using classical molecular dynamics (MD) simulations, the software package GROMACS along with the CLAYFF forcefield and the SPC/E water model. We present the ion distributions and the deformation of the hydrated coordination structures, i.e., the hydration shells of Na+ and Ca2+ in the interlayer, respectively, for MMT in the first-layer, the second-layer, the third-layer, the fourth-layer, and the fifth-layer (1W, 2W, 3W, 4W, and 5W) hydrate states. Our MD simulations show that Na+ in Na-MMT nanopores have an affinity to the ditrigonal cavities of the clay layers and form transient inner-sphere complexes at about 3.8 Å from clay midplane at water contents less than the 5W hydration state. However, these phenomena are not observed in Ca-MMT regardless of swelling states. For Na-MMT, each Na+ is coordinated to four water molecules and one oxygen atom of the clay basal-plane in the first hydration shell at the 1W hydration state, and with five to six water molecules in the first hydration shell within a radius of 3.1 Å at all higher water contents. In Ca-MMT, however each Ca2+ is coordinated to approximately seven water molecules in the first hydration shell at the 1W hydration state and

  8. Terahertz sensing of corneal hydration.

    Science.gov (United States)

    Singh, Rahul S; Tewari, Priyamvada; Bourges, Jean Louis; Hubschman, Jean Pierre; Bennett, David B; Taylor, Zachary D; Lee, H; Brown, Elliott R; Grundfest, Warren S; Culjat, Martin O

    2010-01-01

    An indicator of ocular health is the hydrodyanmics of the cornea. Many corneal disorders deteriorate sight as they upset the normal hydrodynamics of the cornea. The mechanisms include the loss of endothelial pump function of corneal dystophies, swelling and immune response of corneal graft rejection, and inflammation and edema, which accompany trauma, burn, and irritation events. Due to high sensitivity to changes of water content in materials, a reflective terahertz (300 GHz and 3 THz) imaging system could be an ideal tool to measure the hydration level of the cornea. This paper presents the application of THz technology to visualize the hydration content across ex vivo porcine corneas. The corneas, with a thickness variation from 470 - 940 µm, were successfully imaged using a reflective pulsed THz imaging system, with a maximum SNR of 50 dB. To our knowledge, no prior studies have reported on the use of THz in measuring hydration in corneal tissues or other ocular tissues. These preliminary findings indicate that THz can be used to accurately sense hydration levels in the cornea using a pulsed, reflective THz imaging system.

  9. Physical properties of gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Kliner, J.T.R.; Grozic, J.L.H. [Calgary Univ., AB (Canada)

    2003-07-01

    Gas hydrates are naturally occurring, solid crystalline compounds (clathrates) that encapsulate gas molecules inside the lattices of hydrogen bonded water molecules within a specific temperature-pressure stability zone. Estimates of the total quantity of available methane gas in natural occurring hydrates are based on twice the energy content of known conventional fossil fuels reservoirs. Accurate and reliable in-situ quantification techniques are essential in determining the economic viability of this potential energy yield, which is dependent upon several factors such as sensitivity of the temperature-pressure stability zone, sediment type, porosity, permeability, concentration/abundance of free gas, spatial distribution in pore spaces, specific cage occupancy, and the influence of inhibitors. Various techniques like acoustic P and S waves, time domain reflectometry, and electrical resistance have been used to analyze the quantity and spatial distribution of the gas hydrate samples. These techniques were reviewed and the results obtained in the course of gas hydrate research were presented. 34 refs., 8 figs.

  10. Hydration kinetics of transgenic soybeans

    Directory of Open Access Journals (Sweden)

    Aline Francielle Fracasso

    2015-01-01

    Full Text Available The kinetic and experimental analyses of the hydration process of transgenic soybeans (BRS 225 RR are provided. The importance of the hydration process consists of the grain texture modifications which favor grinding and extraction of soybeans. The soaking isotherms were obtained for four different temperatures. Results showed that temperature affected transgenic soybeans´ hydration rate and time. Moisture content d.b. of the soybeans increased from 0.12 ± 0.01 kg kg-1 to 1.45 ± 0.19 kg kg-1 during 270 min. of process. Two models were used to fit the kinetic curves: an empirical model developed by Peleg (1988 and a phenomenological one, proposed by Omoto et al. (2009. The two models adequately represented the hydration kinetics. Peleg model was applied to the experimental data and the corresponding parameters were obtained and correlated to temperature. The model by Omoto et al. (2009 showed a better statistical fitting. Although Ks was affected by temperature (Ks = 0.38079 exp (-2289.3 T-1, the equilibrium concentration remained practically unchanged.

  11. Multi-channel electrical impedance tomography for regional tissue hydration monitoring.

    Science.gov (United States)

    Chen, Xiaohui; Kao, Tzu-Jen; Ashe, Jeffrey M; Boverman, Gregory; Sabatini, James E; Davenport, David M

    2014-06-01

    Poor assessment of hydration status during hemodialysis can lead to under- or over-hydration in patients with consequences of increased morbidity and mortality. In current practice, fluid management is largely based on clinical assessments to estimate dry weight (normal hydration body weight). However, hemodialysis patients usually have co-morbidities that can make the signs of fluid status ambiguous. Therefore, achieving normal hydration status remains a major challenge for hemodialysis therapy. Electrical impedance technology has emerged as a promising method for hydration monitoring due to its non-invasive nature, low cost and ease-of-use. Conventional electrical impedance-based hydration monitoring systems employ single-channel current excitation (either 2-electrode or 4-electrode methods) to perturb and extract averaged impedance from bulk tissue and use generalized models from large populations to derive hydration estimates. In the present study, a prototype, single-frequency electrical impedance tomography (EIT) system with simultaneous multi-channel current excitation was used to enable regional hydration change detection. We demonstrated the capability to detect a difference in daily impedance change between left leg and right leg in healthy human subjects, who wore a compression sock only on one leg to reduce daily gravitational fluid accumulation. The impedance difference corresponded well with the difference of lower leg volume change between left leg and right leg measured by volumetry, which on average is ~35 ml, accounting for 0.7% of the lower leg volume. We have demonstrated the feasibility of using multi-channel EIT to extract hydration information in different tissue layers with minimal skin interference. Our simultaneous, multi-channel current excitation approach provides an effective method to separate electrode contact impedance and skin condition artifacts from hydration signals. The prototype system has the potential to be used in clinical

  12. [PHEMA/PEI]-Cu(II) based immobilized metal affinity chromatography cryogels: Application on the separation of IgG from human plasma.

    Science.gov (United States)

    Bakhshpour, Monireh; Derazshamshir, Ali; Bereli, Nilay; Elkak, Assem; Denizli, Adil

    2016-04-01

    The immobilized metal-affinity chromatography (IMAC) has gained significant interest as a widespread separation and purification tool for therapeutic proteins, nucleic acids and other biological molecules. The enormous potential of IMAC for proteins with natural surface exposed-histidine residues and for recombinant proteins with histidine clusters. Cryogels as monolithic materials have recently been proposed as promising chromatographic adsorbents for the separation of biomolecules in downstream processing. In the present study, IMAC cryogels have been synthesized and utilized for the adsorption and separation of immunoglobulin G (IgG) from IgG solution and whole human plasma. For this purpose, Cu(II)-ions were coupled to poly(hydroxyethyl methacrylate) PHEMA using poly(ethylene imine) (PEI) as the chelating ligand. In this study the cryogels formation optimized by the varied proportion of PEI from 1% to 15% along with different amounts of Cu (II) as chelating metal. The prepared cryogels were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The [PHEMA/PEI]-Cu(II) cryogels were assayed for their capability to bind the human IgG from aqueous solutions. The IMAC cryogels were found to have high affinity toward human IgG. The adsorption of human IgG was investigated onto the PHEMA/PEI cryogels with (10% PEI) and the concentration of Cu (II) varied as 10, 50, 100 and 150 mg/L. The separation of human IgG was achieved in one purification step at pH7.4. The maximum adsorption capacity was observed at the [PHEMA/PEI]-Cu(II) (10% PEI) with 72.28 mg/g of human IgG. The purification efficiency and human IgG purity were investigated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).

  13. Efficient and Tumor Targeted siRNA Delivery by Polyethylenimine-graft-polycaprolactone-block-poly(ethylene glycol)-folate (PEI-PCL-PEG-Fol).

    Science.gov (United States)

    Liu, Li; Zheng, Mengyao; Librizzi, Damiano; Renette, Thomas; Merkel, Olivia M; Kissel, Thomas

    2016-01-04

    Efficient delivery of functional nucleic acids into specific cells or tissues is still a challenge for gene therapy and largely depends on targeted delivery strategies. The folate receptor (FR) is known to be overexpressed extracellularly on a variety of human cancers and is therefore an outstanding gate for tumor-targeted Trojan horse-like delivery of therapeutics. In this study, an amphiphilic and biodegradable ternary copolymer conjugated with folate as ligand, polyethylenimine-graft-polycaprolactone-block-poly(ethylene glycol)-folate (PEI-PCL-PEG-Fol) was synthesized and evaluated for targeted siRNA delivery via folate-FR recognition. The amphiphilic character of similar polymers was shown previously to support endosomal release of endocytosed nanocarriers and to promote formation of long circulating micelles. The obtained PEI-PCL-PEG-Fol exhibited less cytotoxicity in comparison with the corresponding ternary copolymer without folate (PEI-PCL-PEG) and with unmodified PEI25kDa. Stable micelle-like polyplexes with hydrodynamic diameters about 100 nm were found to have a zeta potential of +8.6 mV, which was lower than that of micelleplexes without folate-conjugation (+13-16 mV). Nonetheless, increased cellular uptake and in vitro gene knockdown of PEI-PCL-PEG-Fol/siRNA micelleplexes were observed in SKOV-3 cells, an FR overexpressing cell line, in comparison with the nonfolate-conjugated ones. Moreover, PEI-PCL-PEG-Fol/siRNA micelleplexes exhibited excellent stability in vivo during the analysis of 120 min and a longer circulation half life than hyPEI25kDa/siRNA polyplexes. Most interestingly, the targeted delivery system yielded 17% deposition of the i.v. injected siRNA per gram in the tumor after 24 h due to the effective folate targeting and the prolonged circulation.

  14. Physical activity, hydration and health

    Directory of Open Access Journals (Sweden)

    Ascensión Marcos

    2014-06-01

    Full Text Available Since the beginning of mankind, man has sought ways to promote and preserve health as well as to prevent disease. Hydration, physical activity and exercise are key factors for enhancing human health. However, either a little dose of them or an excess can be harmful for health maintenance at any age. Water is an essential nutrient for human body and a major key to survival has been to prevent dehydration. However, there is still a general controversy regarding the necessary amount to drink water or other beverages to properly get an adequate level of hydration. In addition, up to now the tools used to measure hydration are controversial. To this end, there are several important groups of variables to take into account such as water balance, hydration biomarkers and total body water. A combination of methods will be the most preferred tool to find out any risk or situation of dehydration at any age range. On the other hand, physical activity and exercise are being demonstrated to promote health, avoiding or reducing health problems, vascular and inflammatory diseases and helping weight management. Therefore, physical activity is also being used as a pill within a therapy to promote health and reduce risk diseases, but as in the case of drugs, dose, intensity, frequency, duration and precautions have to be evaluated and taken into account in order to get the maximum effectiveness and success of a treatment. On the other hand, sedentariness is the opposite concept to physical activity that has been recently recognized as an important factor of lifestyle involved in the obesogenic environment and consequently in the risk of the non-communicable diseases. In view of the literature consulted and taking into account the expertise of the authors, in this review a Decalogue of global recommendations is included to achieve an adequate hydration and physical activity status to avoid overweight/obesity consequences.

  15. [Cd3(H2O)3((O3PCH2)2NH-CH2C6H4-COOH)2].11H2O: a layered cadmium phosphonate with reversible dehydration/hydration properties.

    Science.gov (United States)

    Bauer, Sebastian; Marrot, Jérôme; Devic, Thomas; Férey, Gérard; Stock, Norbert

    2007-11-12

    In a recent systematic study on the influence of the reaction temperature on the structure formation in the system CdCl2/H(HO3PCH2)2NH-CH2C6H4-COOH (H5L) /NaOH, [Cd3(H2O)3((O3PCH2)2NH-CH2C6H4-COOH)2].11H2O was obtained as a microcrystalline compound. We have now been able to elucidate the structure from single-crystal data: triclinic, P; a=5.4503(9), b=12.880(2), and c=16.417(3) A; alpha=67.841(6) degrees, beta=80.633(6) degrees, gamma=87.688(8) degrees, V=1052.9(3) A3; Z=1; R1=0.1143, R2=0.2108 (all data); 0.0705, 0.1823 ((I>2sigmaI)). The structure of [Cd3(H2O)3((O3PCH2)2NH-CH2C6H4-COOH)2].11H2O is built up of cadmium phosphonate layers connected by water-mediated hydrogen bonds between aryl-carboxylic acid groups and water molecules coordinated to Cd2+ ions of adjacent layers (C-OH...H2O...H2O-Cd2+). The title compound was characterized by IR spectroscopy and energy dispersive X-ray, elemental, and thermogravimetric analyses. Furthermore, temperature-dependent X-ray diffraction data are presented. [Cd3(H2O)3((O3PCH2)2NH-CH2C6H4-COOH)2].11H2O can be reversibly dehydrated, and mechanical stress and grinding in the presence of water leads to the intercalation of additional water molecules.

  16. Interactions of Organic Additives with Ionic Crystal Hydrates

    Science.gov (United States)

    Füredi-Milhofer, H.; Sikirić, M.; Tunik, L.; Filipović-Vinceković, N.; Garti, N.

    The interactions of two groups of hydrated model crystals, calcium hydrogenphosphate dihydrate (DCPD) vs. octacalcium phosphate (OCP) and calcium oxalate monohydrate (COM) vs. calcium oxalate dihydrate (COD) with different organic additives are considered. DCPD precipitates as platelet-like crystals with the dominant faces shielded by hydrated layers and charged lateral faces. In the second system COM has charged surfaces, while all faces of COD are covered with layers containing water molecules. The organic molecules tested include negatively charged, flexible and rigid small and macromolecules (glutamic and aspartic acid, citrate, hexaammonium polyphosphate, phytate and polyaspartate) and anionic surfactants (sodium dodecyl sulphate, SDS, sodium diisooctyl sulfosuccinate, AOT, sodium cholate NaC and disodium oleoamido PEG-2 sulfosuccinate, PEG). Two types of effects have been demonstrated: (1) Effect on crystal growth morphology: Flexible organic molecules with high charge density and anionic surfactants affected the growth morphology of DCPD and COM by selectively interacting with the charged lateral faces while rigid molecules (phytate, polyaspartate) specifically recognized the dominant (010) face of DCPD due to structural and stereochemical compatibility. (2) Effect on phase composition: Anionic surfactants at concentrations above the cmc promoted growth of OCP and COD respectively by selectively adsorbing at, and inhibiting growth oif nuclei of DCPD and/or COM, which were dominant in the respective control systems. The effect was especially pronounced in the calcium oxalate precipitation system, where in some cases complete reversal of the phase composition occurred. The important role of the hydrated layer, as part of the structure of the investigated crystal hydrates, in the above crystal additive interactions is discussed.

  17. Seismic reflections associated with submarine gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Andreassen, K.

    1995-12-31

    Gas hydrates are often suggested as a future energy resource. This doctoral thesis improves the understanding of the concentration and distribution of natural submarine gas hydrates. The presence of these hydrates are commonly inferred from strong bottom simulating reflection (BSR). To investigate the nature of BSR, this work uses seismic studies of hydrate-related BSRs at two different locations, one where gas hydrates are accepted to exist and interpreted to be very extensive (in the Beaufort Sea), the other with good velocity data and downhole logs available (offshore Oregon). To ascertain the presence of free gas under the BSR, prestack offset data must supplement near-vertical incidence seismic data. A tentative model for physical properties of sediments partially saturated with gas hydrate and free gas is presented. This model, together with drilling information and seismic data containing the BSR beneath the Oregon margin and the Beaufort Sea, made it possible to better understand when to apply the amplitude-versus-offset (AVO) method to constrain BSR gas hydrate and gas models. Distribution of natural gas hydrates offshore Norway and Svalbard is discussed and interpreted as reflections from the base of gas hydrate-bearing sediments, overlying sediments containing free gas. Gas hydrates inferred to exist at the Norwegian-Svalbard continental margin correlate well with Cenozoic depocenters, and the associated gas is assumed to be mainly biogenic. Parts of that margin have a high potential for natural gas hydrates of both biogenic and thermogenic origin. 235 refs., 86 figs., 4 tabs.

  18. Handbook of gas hydrate properties and occurrence

    Energy Technology Data Exchange (ETDEWEB)

    Kuustraa, V.A.; Hammershaimb, E.C.

    1983-12-01

    This handbook provides data on the resource potential of naturally occurring hydrates, the properties that are needed to evaluate their recovery, and their production potential. The first two chapters give data on the naturally occurring hydrate potential by reviewing published resource estimates and the known and inferred occurrences. The third and fourth chapters review the physical and thermodynamic properties of hydrates, respectively. The thermodynamic properties of hydrates that are discussed include dissociation energies and a simplified method to calculate them; phase diagrams for simple and multi-component gases; the thermal conductivity; and the kinetics of hydrate dissociation. The final chapter evaluates the net energy balance of recovering hydrates and shows that a substantial positive energy balance can theoretically be achieved. The Appendices of the Handbook summarize physical and thermodynamic properties of gases, liquids and solids that can be used in designing and evaluating recovery processes of hydrates. 158 references, 67 figures, 47 tables.

  19. Separation of water through gas hydrate formation

    DEFF Research Database (Denmark)

    Boch Andersen, Torben; Thomsen, Kaj

    2009-01-01

    Gas hydrate is normally recognized as a troublemaker in the oil and gas industry. However, gas hydrate has some interesting possibilities when used in connection with separation of water. Nordic Sugar has investigated the possibility of using gas hydrates for concentration of sugar juice. The goa...... volumes and the needs for high pressure. The process could be interesting for concentration of heat sensitive, high value products......Gas hydrate is normally recognized as a troublemaker in the oil and gas industry. However, gas hydrate has some interesting possibilities when used in connection with separation of water. Nordic Sugar has investigated the possibility of using gas hydrates for concentration of sugar juice. The goal...... of the project was to formulate an alternative separation concept, which can replace the traditional water evaporation process in the sugar production. Work with the separation concept showed that gas hydrates can be used for water separation. The process is not suitable for sugar production because of large...

  20. Low temperature X-ray diffraction studies of natural gas hydrate samples from the Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Rawn, C.J. [Oak Ridge National Laboratory, Oak Ridge, TN (United States). Materials Science and Technology Div.; Sassen, R. [Texas A and M Univ., College Station, TX (United States). Geochemical and Environmental Research Group; Ulrich, S.M.; Phelps, T.J. [Oak Ridge National Laboratory, Oak Ridge, TN (United States). Biosciences Div.; Chakoumakos, B.C. [Oak Ridge National Laboratory, Oak Ridge, TN (United States). Neutron Scattering Science Div.; Payzant, E.A. [Oak Ridge National Laboratory, Oak Ridge, TN (United States). Center for Nanophase Materials Science

    2008-07-01

    Quantitative studies of natural clathrate hydrates are hampered by the difficulties associated with obtaining pristine samples for the sea floor without comprising their integrity. This paper discussed X-ray power diffraction studies conducted to measure natural gas hydrate samples obtained from the Green Canyon in the Gulf of Mexico. Data on the hydrate deposits were initially collected in 2002. The X-ray diffraction data were collected in order to examine the structure 2 (s2) gas hydrates as functions of temperature and time. A diffractometer with a theta-theta goniometer modified with a helium closed cycle refrigerator and temperature controller was used. Aragonite, quartz and halite phases were determined in the decomposed sample. Refined phase fractions for both the ice and the s2 hydrate were obtained as a function of temperature. Results of the study demonstrated that the amount of hydrates decreased with increasing temperatures and amounts of time. Large pieces of the hydrate showed heterogenous ice content. Dissociation rates were higher at lower temperatures. It was concluded that unusual trends observed for the smaller lattice parameter of the hydrates resulted from the formation of ice layers that acted as barriers to the released gases and caused increased isostatic pressures around the hydrate core. 9 refs., 6 figs.

  1. Well log characterization of natural gas hydrates

    Science.gov (United States)

    Collett, Timothy S.; Lee, Myung W.

    2011-01-01

    In the last 25 years we have seen significant advancements in the use of downhole well logging tools to acquire detailed information on the occurrence of gas hydrate in nature: From an early start of using wireline electrical resistivity and acoustic logs to identify gas hydrate occurrences in wells drilled in Arctic permafrost environments to today where wireline and advanced logging-while-drilling tools are routinely used to examine the petrophysical nature of gas hydrate reservoirs and the distribution and concentration of gas hydrates within various complex reservoir systems. The most established and well known use of downhole log data in gas hydrate research is the use of electrical resistivity and acoustic velocity data (both compressional- and shear-wave data) to make estimates of gas hydrate content (i.e., reservoir saturations) in various sediment types and geologic settings. New downhole logging tools designed to make directionally oriented acoustic and propagation resistivity log measurements have provided the data needed to analyze the acoustic and electrical anisotropic properties of both highly inter-bedded and fracture dominated gas hydrate reservoirs. Advancements in nuclear-magnetic-resonance (NMR) logging and wireline formation testing have also allowed for the characterization of gas hydrate at the pore scale. Integrated NMR and formation testing studies from northern Canada and Alaska have yielded valuable insight into how gas hydrates are physically distributed in sediments and the occurrence and nature of pore fluids (i.e., free-water along with clay and capillary bound water) in gas-hydrate-bearing reservoirs. Information on the distribution of gas hydrate at the pore scale has provided invaluable insight on the mechanisms controlling the formation and occurrence of gas hydrate in nature along with data on gas hydrate reservoir properties (i.e., permeabilities) needed to accurately predict gas production rates for various gas hydrate

  2. Thermal conductivity of hydrate-bearing sediments

    Science.gov (United States)

    Cortes, Douglas D.; Martin, Ana I.; Yun, Tae Sup; Francisca, Franco M.; Santamarina, J. Carlos; Ruppel, Carolyn

    2009-11-01

    A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate-saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate-bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces.

  3. Thermal conductivity of hydrate-bearing sediments

    Science.gov (United States)

    Cortes, D.D.; Martin, A.I.; Yun, T.S.; Francisca, F.M.; Santamarina, J.C.; Ruppel, C.

    2009-01-01

    A thorough understanding of the thermal conductivity of hydrate-bearing sediments is necessary for evaluating phase transformation processes that would accompany energy production from gas hydrate deposits and for estimating regional heat flow based on the observed depth to the base of the gas hydrate stability zone. The coexistence of multiple phases (gas hydrate, liquid and gas pore fill, and solid sediment grains) and their complex spatial arrangement hinder the a priori prediction of the thermal conductivity of hydrate-bearing sediments. Previous studies have been unable to capture the full parameter space covered by variations in grain size, specific surface, degree of saturation, nature of pore filling material, and effective stress for hydrate-bearing samples. Here we report on systematic measurements of the thermal conductivity of air dry, water- and tetrohydrofuran (THF)-saturated, and THF hydrate-saturated sand and clay samples at vertical effective stress of 0.05 to 1 MPa (corresponding to depths as great as 100 m below seafloor). Results reveal that the bulk thermal conductivity of the samples in every case reflects a complex interplay among particle size, effective stress, porosity, and fluid-versus-hydrate filled pore spaces. The thermal conductivity of THF hydrate-bearing soils increases upon hydrate formation although the thermal conductivities of THF solution and THF hydrate are almost the same. Several mechanisms can contribute to this effect including cryogenic suction during hydrate crystal growth and the ensuing porosity reduction in the surrounding sediment, increased mean effective stress due to hydrate formation under zero lateral strain conditions, and decreased interface thermal impedance as grain-liquid interfaces are transformed into grain-hydrate interfaces. Copyright 2009 by the American Geophysical Union.

  4. The effect of hydrate saturation on water retention curves in hydrate-bearing sediments

    Science.gov (United States)

    Mahabadi, Nariman; Zheng, Xianglei; Jang, Jaewon

    2016-05-01

    The experimental measurement of water retention curve in hydrate-bearing sediments is critically important to understand the behavior of hydrate dissociation and gas production. In this study, tetrahydrofuran (THF) is selected as hydrate former. The pore habit of THF hydrates is investigated by visual observation in a transparent micromodel. It is confirmed that THF hydrates are not wetting phase on the quartz surface of the micromodel and occupy either an entire pore or part of pore space resulting in change in pore size distribution. And the measurement of water retention curves in THF hydrate-bearing sediments with hydrate saturation ranging from Sh = 0 to Sh = 0.7 is conducted for excess water condition. The experimental results show that the gas entry pressure and the capillary pressure increase with increasing hydrate saturation. Based on the experimental results, fitting parameters for van Genuchten equation are suggested for different hydrate saturation conditions.

  5. Aspectos clínicos do entrópio de desenvolvimento em cães da raça Shar Pei Clinical aspects of developmental entropion in Shar Pei dogs

    Directory of Open Access Journals (Sweden)

    F.A.B. Viana

    2006-04-01

    Full Text Available Avaliaram-se os aspectos clínicos do entrópio de desenvolvimento em filhotes de cães da raça Shar Pei. Utilizaram-se 50 animais com idades entre 18 e 128 dias, que apresentavam graus variáveis de inversão palpebral e lesões oculares, as quais foram classificadas de acordo com um modelo específico proposto. As lesões encontradas foram fotofobia, epífora, inversão da margem palpebral, blefarospasmo, conjuntivite, quemose, edema, erosão e vascularização da córnea e phthisis bulbi.The clinical aspects of entropion in puppies of the Shar Pei breed were studied using 50 animals, 18 to 128 day-old, that presented variable degrees of palpebral inversion and ocular lesions. The ocular lesions were classified according to a specific model. Photophobia, epiphora, palpebral margins inversion, blepharospasm, conjuntivitis, quemosis, corneal edema, erosion and vascularization and phthisis bulbi were observed.

  6. Gas hydrate decomposition recorded by authigenic barite at pockmark sites of the northern Congo Fan

    Science.gov (United States)

    Kasten, Sabine; Nöthen, Kerstin; Hensen, Christian; Spieß, Volkhard; Blumenberg, Martin; Schneider, Ralph R.

    2012-12-01

    The geochemical cycling of barium was investigated in sediments of pockmarks of the northern Congo Fan, characterized by surface and subsurface gas hydrates, chemosynthetic fauna, and authigenic carbonates. Two gravity cores retrieved from the so-called Hydrate Hole and Worm Hole pockmarks were examined using high-resolution pore-water and solid-phase analyses. The results indicate that, although gas hydrates in the study area are stable with respect to pressure and temperature, they are and have been subject to dissolution due to methane-undersaturated pore waters. The process significantly driving dissolution is the anaerobic oxidation of methane (AOM) above the shallowest hydrate-bearing sediment layer. It is suggested that episodic seep events temporarily increase the upward flux of methane, and induce hydrate formation close to the sediment surface. AOM establishes at a sediment depth where the upward flux of methane from the uppermost hydrate layer counterbalances the downward flux of seawater sulfate. After seepage ceases, AOM continues to consume methane at the sulfate/methane transition (SMT) above the hydrates, thereby driving the progressive dissolution of the hydrates "from above". As a result the SMT migrates downward, leaving behind enrichments of authigenic barite and carbonates that typically precipitate at this biogeochemical reaction front. Calculation of the time needed to produce the observed solid-phase barium enrichments above the present-day depths of the SMT served to track the net downward migration of the SMT and to estimate the total time of hydrate dissolution in the recovered sediments. Methane fluxes were higher, and the SMT was located closer to the sediment surface in the past at both sites. Active seepage and hydrate formation are inferred to have occurred only a few thousands of years ago at the Hydrate Hole site. By contrast, AOM-driven hydrate dissolution as a consequence of an overall net decrease in upward methane flux seems to

  7. Animated molecular dynamics simulations of hydrated caesium-smectite interlayers

    Directory of Open Access Journals (Sweden)

    Sposito Garrison

    2002-09-01

    Full Text Available Computer animation of center of mass coordinates obtained from 800 ps molecular dynamics simulations of Cs-smectite hydrates (1/3 and 2/3 water monolayers provided information concerning the structure and dynamics of the interlayer region that could not be obtained through traditional simulation analysis methods. Cs+ formed inner sphere complexes with the mineral surface, and could be seen to jump from one attracting location near a layer charge site to the next, while water molecules were observed to migrate from the hydration shell of one ion to that of another. Neighboring ions maintained a partial hydration shell by sharing water molecules, such that a single water molecule hydrated two ions simultaneously for hundreds of picoseconds. Cs-montmorillonite hydrates featured the largest extent of this sharing interaction, because interlayer ions were able to inhabit positions near surface cavities as well as at their edges, close to oxygen triads. The greater positional freedom of Cs+ within the montmorillonite interlayer, a result of structural hydroxyl orientation and low tetrahedral charge, promoted the optimization of distances between cations and water molecules required for water sharing. Preference of Cs+ for locations near oxygen triads was observed within interlayer beidellite and hectorite. Water molecules also could be seen to interact directly with the mineral surface, entering its surface cavities to approach attracting charge sites and structural hydroxyls. With increasing water content, water molecules exhibited increased frequency and duration of both cavity habitation and water sharing interactions. Competition between Cs+ and water molecules for surface sites was evident. These important cooperative and competitive features of interlayer molecular behavior were uniquely revealed by animation of an otherwise highly complex simulation output.

  8. An Improved Clearing and Mounting Solution to Replace Chloral Hydrate in Microscopic Applications

    Directory of Open Access Journals (Sweden)

    Thomas S. Villani

    2013-05-01

    Full Text Available Premise of the study: This study presents Visikol™, a new proprietary formulation that can be used as an efficient replacement for chloral hydrate as a clearing agent for microscopic examination. In the United States, chloral hydrate is regulated and therefore difficult to acquire. Methods and Results: Fresh and dry samples of the following plants: ginger (Zingiber officinale, maté (Ilex paraguariensis, lime basil (Ocimum americanum, oregano (Origanum vulgare, and mouse-ear cress (Arabidopsis thaliana, were cleared using Visikol or chloral hydrate solution and compared using a light microscope. Conclusions: This new method can be used successfully to clear specimens, allowing identification of diagnostic characteristics for the identification of plant materials. Visikol is as effective as chloral hydrate in providing clarity and resolution of all tissues examined. Tissues become transparent, allowing observation of deeper layers of cells and making it effective in research, botanical and quality control, and for educational applications.

  9. Gas hydrate, fluid flow and free gas: Formation of the bottom-simulating reflector

    Science.gov (United States)

    Haacke, R. Ross; Westbrook, Graham K.; Hyndman, Roy D.

    2007-09-01

    Gas hydrate in continental margins is commonly indicated by a prominent bottom-simulating seismic reflector (BSR) that occurs a few hundred metres below the seabed. The BSR marks the boundary between sediments containing gas hydrate above and free gas below. Most of the reflection amplitude is caused by the underlying free gas. Gas hydrate can occur without a BSR, however, and the controls on its formation are not well understood. Here we describe two complementary mechanisms for free gas accumulation beneath the gas hydrate stability zone (GHSZ). The first is the well-recognised hydrate recycling mechanism that generates gas from dissociating hydrate when the base of the GHSZ moves upward relative to hydrate-bearing sediment. The second is a recently identified mechanism in which the relationship between the advection and diffusion of dissolved gas with the local solubility curve allows the liquid phase to become saturated in a thick layer beneath the GHSZ when hydrate is present near its base. This mechanism for gas production (called the solubility-curvature mechanism) is possible in systems where the influence of diffusion becomes important relative to the influence of advection and where the gas-water solubility decreases to a minimum several hundred metres below the GHSZ. We investigate a number of areas in which gas hydrate occurs to determine where gas formation is dominated by the solubility-curvature mechanism and where it is dominated by hydrate recycling. We show that the former is dominant in areas with low rates of upward fluid flow (such as old, rifted continental margins), low rates of seafloor uplift, and high geothermal gradient and/or pressure. Conversely, free-gas formation is dominated by hydrate recycling where there are rapid rates of upward fluid flow and seabed uplift (such as in subduction zone accretionary wedges). Using these two mechanisms to investigate the formation of free gas beneath gas hydrate in continental margins, we are able

  10. Synthesis of hydrated lutetium carbonate

    Energy Technology Data Exchange (ETDEWEB)

    Song Liu [South China Univ. of Technology, Dept. of Applied Chemistry, Guangdong (China); Rong-jun Ma [Changsha Research Institute of Minig and Metallurgy, Hunan (China)

    1997-09-01

    Crystalline lutetium carbonate was synthesized for the corresponding chloride using ammonium bicarbonate as precipitant. The chemical analyses suggest that the synthesized lutetium carbonate is a hydrated basic carbonate or oxycarbonate. The X-ray powder diffraction data are presented. The IR data for the compound show the presence of two different carbonate groups. There is no stable intermediate carbonate in the process of thermal decomposition of the lutetium carbonate. (au) 15 refs.

  11. Separation of macromolecular proteins and rejection of toxic heavy metal ions by PEI/cSMM blend UF membranes.

    Science.gov (United States)

    Kanagaraj, P; Nagendran, A; Rana, D; Matsuura, T; Neelakandan, S

    2015-01-01

    The charged surface modifying macromolecule (cSMM) was blended into the casting solution of poly(ether imide) (PEI) to prepare surface modified ultrafiltration membranes by phase inversion technique. The separation of proteins including bovine serum albumin, egg albumin, pepsin and trypsin was investigated by the fabricated membranes. On increasing cSMM content, solute rejection decreases whereas membrane flux increases. The pore size and surface porosity of the 5 wt% cSMM blend PEI membranes increases to 41.4 Å and 14.8%, respectively. Similarly, the molecular weight cut-off of the membranes ranged from 20 to 45 kDa, depending on the various compositions of the prepared membranes. The toxic heavy metal ions Cu(II), Cr(III), Zn(II) and Pb(II) from aqueous solutions were subjected to rejection by the prepared blended membrane with various concentration of polyethyleneimine (PETIM) as water soluble polymeric ligand. It was found that the rejection behavior of metal ion depends on the PETIM concentration and the stability complexation of metal ion with ligand.

  12. Crystallite size distributions of marine gas hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Klapp, S.A.; Bohrmann, G.; Abegg, F. [Bremen Univ., Bremen (Germany). Research Center of Ocean Margins; Hemes, S.; Klein, H.; Kuhs, W.F. [Gottingen Univ., Gottingen (Germany). Dept. of Crystallography

    2008-07-01

    Experimental studies were conducted to determine the crystallite size distributions of natural gas hydrate samples retrieved from the Gulf of Mexico, the Black Sea, and a hydrate ridge located near offshore Oregon. Synchrotron radiation technology was used to provide the high photon fluxes and high penetration depths needed to accurately analyze the bulk sediment samples. A new beam collimation diffraction technique was used to measure gas hydrate crystallite sizes. The analyses showed that gas hydrate crystals were globular in shape. Mean crystallite sizes ranged from 200 to 400 {mu}m for hydrate samples taken from the sea floor. Larger grain sizes in the hydrate ridge samples suggested differences in hydrate formation ages or processes. A comparison with laboratory-produced methane hydrate samples showed half a lognormal curve with a mean value of 40{mu}m. Results of the study showed that a cautious approach must be adopted when transposing crystallite-size sensitive physical data from laboratory-made gas hydrates to natural settings. It was concluded that crystallite size information may also be used to resolve the formation ages of gas hydrates when formation processes and conditions are constrained. 48 refs., 1 tab., 9 figs.

  13. IMPORTANCE OF HYDRATION IN SPORTS

    Directory of Open Access Journals (Sweden)

    Goran Vasić

    2008-08-01

    Full Text Available Importance of hydration is detrmined by importance of functions of water in the human organism: i.e. regulation of body temperature, transport, excretion of waste materials through urine, digestion of food which is facilititated by saliva and gastric juices, maintenance of flexibility of organs and tissues About 60 % body mass of an adult person (males: 61 %, females: 54 % is made up of water. Water content of a newly born baby reaches 77 %, and it is up to 50 % in adults. It is very important for sportsmen to provide adequate hydration during and after the time of bodily activities. A symptom of water shortage is thirst. However, thirst is a late response of an organism and it occurs when dehydration has already taken place. Minimum in take of fluids in humans should range between one-and-half to two liters. It has been known for a long time that there is no success in sport without proper hydration in a sportsman.

  14. The effect of reservoir heterogeneity on gas production from hydrate accumulations in the permafrost

    Energy Technology Data Exchange (ETDEWEB)

    Reagan, M. T.; Kowalsky, M B.; Moridis, G. J.; Silpngarmlert, S.

    2010-05-01

    The quantity of hydrocarbon gases trapped in natural hydrate accumulations is enormous, leading to significant interest in the evaluation of their potential as an energy source. Large volumes of gas can be readily produced at high rates for long times from methane hydrate accumulations in the permafrost by means of depressurization-induced dissociation combined with conventional technologies and horizontal or vertical well configurations. Initial studies on the possibility of natural gas production from permafrost hydrates assumed homogeneity in intrinsic reservoir properties and in the initial condition of the hydrate-bearing layers (either due to the coarseness of the model or due to simplifications in the definition of the system). These results showed great promise for gas recovery from Class 1, 2, and 3 systems in the permafrost. This work examines the consequences of inevitable heterogeneity in intrinsic properties, such as in the porosity of the hydrate-bearing formation, or heterogeneity in the initial state of hydrate saturation. Heterogeneous configurations are generated through multiple methods: (1) through defining heterogeneous layers via existing well-log data, (2) through randomized initialization of reservoir properties and initial conditions, and (3) through the use of geostatistical methods to create heterogeneous fields that extrapolate from the limited data available from cores and well-log data. These extrapolations use available information and established geophysical methods to capture a range of deposit properties and hydrate configurations. The results show that some forms of heterogeneity, such as horizontal stratification, can assist in production of hydrate-derived gas. However, more heterogeneous structures can lead to complex physical behavior within the deposit and near the wellbore that may obstruct the flow of fluids to the well, necessitating revised production strategies. The need for fine discretization is crucial in all cases to

  15. Pore fluid geochemistry from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    Science.gov (United States)

    Torres, M.E.; Collett, T.S.; Rose, K.K.; Sample, J.C.; Agena, W.F.; Rosenbaum, E.J.

    2011-01-01

    The BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well was drilled and cored from 606.5 to 760.1. m on the North Slope of Alaska, to evaluate the occurrence, distribution and formation of gas hydrate in sediments below the base of the ice-bearing permafrost. Both the dissolved chloride and the isotopic composition of the water co-vary in the gas hydrate-bearing zones, consistent with gas hydrate dissociation during core recovery, and they provide independent indicators to constrain the zone of gas hydrate occurrence. Analyses of chloride and water isotope data indicate that an observed increase in salinity towards the top of the cored section reflects the presence of residual fluids from ion exclusion during ice formation at the base of the permafrost layer. These salinity changes are the main factor controlling major and minor ion distributions in the Mount Elbert Well. The resulting background chloride can be simulated with a one-dimensional diffusion model, and the results suggest that the ion exclusion at the top of the cored section reflects deepening of the permafrost layer following the last glaciation (???100 kyr), consistent with published thermal models. Gas hydrate saturation values estimated from dissolved chloride agree with estimates based on logging data when the gas hydrate occupies more than 20% of the pore space; the correlation is less robust at lower saturation values. The highest gas hydrate concentrations at the Mount Elbert Well are clearly associated with coarse-grained sedimentary sections, as expected from theoretical calculations and field observations in marine and other arctic sediment cores. ?? 2009 Elsevier Ltd.

  16. Investigation into the Formation and Adhesion of Cyclopentane Hydrates on Mechanically Robust Vapor-Deposited Polymeric Coatings.

    Science.gov (United States)

    Sojoudi, Hossein; Walsh, Matthew R; Gleason, Karen K; McKinley, Gareth H

    2015-06-09

    Blockage of pipelines by formation and accumulation of clathrate hydrates of natural gases (also called gas hydrates) can compromise project safety and economics in oil and gas operations, particularly at high pressures and low temperatures such as those found in subsea or arctic environments. Cyclopentane (CyC5) hydrate has attracted interest as a model system for studying natural gas hydrates, because CyC5, like typical natural gas hydrate formers, is almost fully immiscible in water; and thus CyC5 hydrate formation is governed not only by thermodynamic phase considerations but also kinetic factors such as the hydrocarbon/water interfacial area, as well as mass and heat transfer constraints, as for natural gas hydrates. We present a macroscale investigation of the formation and adhesion strength of CyC5 hydrate deposits on bilayer polymer coatings with a range of wettabilities. The polymeric bilayer coatings are developed using initiated chemical vapor deposition (iCVD) of a mechanically robust and densely cross-linked polymeric base layer (polydivinylbenzene or pDVB) that is capped with a covalently attached thin hydrate-phobic fluorine-rich top layer (poly(perfluorodecyl acrylate) or pPFDA). The CyC5 hydrates are formed from CyC5-in-water emulsions, and differential scanning calorimetry (DSC) is used to confirm the thermal dissociation properties of the solid hydrate deposits. We also investigate the adhesion of the CyC5 hydrate deposits on bare and bilayer polymer-coated silicon and steel substrates. Goniometric measurements with drops of CyC5-in-water emulsions on the coated steel substrates exhibit advancing contact angles of 148.3 ± 4.5° and receding contact angles of 142.5 ± 9.8°, indicating the strongly emulsion-repelling nature of the iCVD coatings. The adhesion strength of the CyC5 hydrate deposits is reduced from 220 ± 45 kPa on rough steel substrates to 20 ± 17 kPa on the polymer-coated steel substrates. The measured strength of CyC5 hydrate

  17. Fabrication of positively charged nanofiltration membrane via the layer-by-layer assembly of graphene oxide and polyethylenimine for desalination

    Science.gov (United States)

    Nan, Qian; Li, Pei; Cao, Bing

    2016-11-01

    Highly positively charged nanofiltration (NF) membranes have been prepared via a layer-by-layer (LbL) self-assembly technique using graphene oxide (GO) and polyethyleneimine (PEI). The high aspect ratio and unique 2D structure of GO nanosheets enabled them to be easily assembled on the membrane surface, and the intrinsic low resistant channels within the GO nanosheets resulted in a high water flux of the membrane. By assembled a PEI layer on the membrane outer surface, the composite membrane exhibited high positive charge and resulted in the high rejections to multivalent ions. The effects of deposition time, PEI and GO concentrations on separation performance of the NF membranes were detailed studied. The best performance among all the membranes was achieved with salt rejections of 93.9% and 38.1% for Mg2+ and Na+, and a water flux of 4.2 L/m2 h bar at 30 °C and 0.5 MPa. The attractive performance of these NF membranes showed a great potential in the industrial application of water softening.

  18. The potential use of a layer-by-layer strategy to develop LDPE antimicrobial films coated with silver nanoparticles for packaging applications.

    Science.gov (United States)

    Azlin-Hasim, Shafrina; Cruz-Romero, Malco C; Cummins, Enda; Kerry, Joseph P; Morris, Michael A

    2016-01-01

    Commercial low-density polyethylene (LDPE) films were UV/ozone treated and coated using a layer-by-layer (LbL) technique by alternating the deposition of polyethyleneimine (PEI) and poly(acrylic acid) (PAA) polymer solutions and antimicrobial silver (Ag). The effects of the initial pH of the PEI/PAA polymer solutions alternating layers (pH 10.5/4 or 9/6.5) on the antimicrobial activity of the developed LbL coatings combined with Ag against Gram-negative and Gram-positive bacteria were investigated. The results from fourier transform infrared spectroscopy and toluidine blue O assay showed that LDPE LbL coated using PEI/PAA polymer solutions with initial pH of 10.5/4 significantly increased the presence of carboxylic acid groups and after Ag attachment the coating had higher antimicrobial activity against both Gram-negative and Gram-positive bacteria compared to the LDPE LbL coated using PEI/PAA polymer solutions with initial pH of 9/6.5. The LDPE LbL coated films using non-modified pH PEI/PAA polymer solutions decreased the water contact-angle indicating an increased hydrophilicity of the film, also increased the tensile strength and roughness of LDPE LbL coated films compared to uncoated LbL samples. The LDPE LbL coated films attached with Ag(+) were UV/ozone treated for 20 min to oxidise Ag(+) to Ag(0). The presence of Ag(0) (Ag nanoparticles (NPs)) on the LDPE LbL coated films was confirmed by XRD, UV-vis spectrophotometer and colour changes. The overall results demonstrated that the LbL technique has the potential to be used as a coating method containing antimicrobial Ag NPs and that the manufactured films could potentially be applied as antimicrobial packaging.

  19. Study of Formation Mechanisms of Gas Hydrate

    Science.gov (United States)

    Yang, Jia-Sheng; Wu, Cheng-Yueh; Hsieh, Bieng-Zih

    2015-04-01

    Gas hydrates, which had been found in subsurface geological environments of deep-sea sediments and permafrost regions, are solid crystalline compounds of gas molecules and water. The estimated energy resources of hydrates are at least twice of that of the conventional fossil fuel in the world. Gas hydrates have a great opportunity to become a dominating future energy. In the past years, many laboratory experiments had been conducted to study chemical and thermodynamic characteristics of gas hydrates in order to investigate the formation and dissociation mechanisms of hydrates. However, it is difficult to observe the formation and dissociation of hydrates in a porous media from a physical experiment directly. The purpose of this study was to model the dynamic formation mechanisms of gas hydrate in porous media by reservoir simulation. Two models were designed for this study: 1) a closed-system static model with separated gas and water zones; this model was a hydrate equilibrium model to investigate the behavior of the formation of hydrates near the initial gas-water contact; and 2) an open-system dynamic model with a continuous bottom-up gas flow; this model simulated the behavior of gas migration and studied the formation of hydrates from flowed gas and static formation water in porous media. A phase behavior module was developed in this study for reservoir simulator to model the pressure-volume-temperature (PVT) behavior of hydrates. The thermodynamic equilibriums and chemical reactions were coupled with the phase behavior module to have functions modelling the formation and dissociation of hydrates from/to water and gas. The simulation models used in this study were validated from the code-comparison project proposed by the NETL. According to the modelling results of the closed-system static model, we found that predominated location for the formation of hydrates was below the gas-water contact (or at the top of water zone). The maximum hydrate saturation

  20. Preparation and characterization of polymer blend based on sulfonated poly (ether ether ketone) and polyetherimide (SPEEK/PEI) as proton exchange membranes for fuel cells

    Energy Technology Data Exchange (ETDEWEB)

    Hashim, Nordiana; Ali, Ab Malik Marwan [Ionic Material and Devices Research Laboratory, Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia); Lepit, Ajis; Rasmidi, Rosfayanti [Faculty of Applied Sciences, Universiti Teknologi MARA Sabah, Beg Berkunci 71, 88997 Kota Kinabalu (Malaysia); Subban, Ri Hanum Yahaya [Faculty of Applied Sciences, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia); Institute of Science, Universiti Teknologi MARA, 40450 Shah Alam (Malaysia); Yahya, Muhd Zu Azhan [Faculty of Defence Science & Technology, Universiti Pertahanan Nasional Malaysia, 57000 Kuala Lumpur (Malaysia)

    2015-08-28

    Blends of sulfonated poly (ether ether ketone) (SPEEK) and polyetherimide (PEI) were prepared in five different weight ratios using N-methyl-2-pyrrolidone (NMP) as solvent by the solution cast technique. The degree of sulfonation (DS) of the sulfonated PEEK was determined from deuterated dimethyl sulfoxide (DMSO-d{sub 6}) solution of the purified polymer using {sup 1}H NMR method. The properties studied in the present investigation includes conductivity, water uptake, thermal stability and structure analysis of pure SPEEK as well as SPEEK-PEI polymer blend membranes. The experimental results show that the conductivity of the membranes increased with increase in temperature from 30 to 80°C, except for that of pure SPEEK membrane which increased with temperature from 30 to 60°C while its conductivity decreased with increasing temperature from 60 to 80°C. The conductivity of 70wt.%SPEEK-30wt.%PEI blend membrane at 80% relative humidity (RH) is found to be 1.361 × 10{sup −3} Scm{sup −1} at 30°C and 3.383 × 10{sup −3} Scm{sup −1} at 80°C respectively. It was also found that water uptake and thermal stability of the membranes slightly improved upon blending with PEI. Structure analysis was carried out using Fourier Transform Infrared (FTIR) spectroscopy which revealed considerable interactions between sulfonic acid group of SPEEK and imide groups of PEI. Modification of SPEEK by blending with PEI shows good potential for improving the electrical and physical properties of proton exchange membranes.

  1. Hydrothermal synthesis of nanostructured hybrids based on iron oxide and branched PEI polymers. Influence of high pressure on structure and morphology

    Energy Technology Data Exchange (ETDEWEB)

    Popescu, L.M., E-mail: mpopescu@imnr.ro [National R& D Institute for Non-ferrous and Rare Metals, 102 Biruintei Blvd, Pantelimon, Judetul Ilfov (Romania); Piticescu, R.M., E-mail: roxana@imnr.ro [National R& D Institute for Non-ferrous and Rare Metals, 102 Biruintei Blvd, Pantelimon, Judetul Ilfov (Romania); Petriceanu, M., E-mail: mirelap@imnr.ro [National R& D Institute for Non-ferrous and Rare Metals, 102 Biruintei Blvd, Pantelimon, Judetul Ilfov (Romania); Ottaviani, M.F., E-mail: maria.ottaviani@uniurb.it [University of Urbino “Carlo Bo”, Department of Earth, Life and Environmental Sciences, Urbino (Italy); Cangiotti, M., E-mail: michela.cangiotti@uniurb.it [University of Urbino “Carlo Bo”, Department of Earth, Life and Environmental Sciences, Urbino (Italy); Vasile, E., E-mail: eugeniuvasile@yahoo.com [University Politehnica of Bucharest, Bucharest (Romania); National R& D Institute for Non-ferrous and Rare Metals, 102 Biruintei Blvd, Pantelimon, Judetul Ilfov (Romania); Dîrtu, M.M., E-mail: marinela.dirtu@uclouvain.be [Institute of Condensed Mater and Nanosciences, Molecules, Solids and Reactivity (IMCN/MOST), Université Catholique de Louvain, Place L. Pasteur 1, 1348 Louvain-la-Neuve (Belgium); Wolff, M., E-mail: mariusz.wolff@uclouvain.be [Institute of Condensed Mater and Nanosciences, Molecules, Solids and Reactivity (IMCN/MOST), Université Catholique de Louvain, Place L. Pasteur 1, 1348 Louvain-la-Neuve (Belgium); Garcia, Y., E-mail: yann.garcia@uclouvain.be [Institute of Condensed Mater and Nanosciences, Molecules, Solids and Reactivity (IMCN/MOST), Université Catholique de Louvain, Place L. Pasteur 1, 1348 Louvain-la-Neuve (Belgium); and others

    2015-07-01

    Homogeneous hybrids in which iron oxide nanoparticles are entrapped within polymer structure are of interest for their potential applications in biomedical field, such as diagnostic, therapeutic and theranostic purposes. For this reason, hybrid nanomaterials based on branched polyethyleneimine (PEI) and iron oxide with different ratios were synthesized in a single step by hydrothermal procedure at high pressure and low temperature. Iron oxide is formed in the presence of branched PEI and the interaction between them takes place in the reaction medium. The influence of synthesis parameters on the hybrid formation, as well as chemical and structural properties was studied by means of FTIR, DSC-TG, HRTEM, electron paramagnetic resonance (EPR), magnetic measurements (SQUID) and {sup 57}Fe Mössbauer analyses. It has been shown that synthesis parameters influence thermal stability and morphology of the hybrids. FeO(OH) crystallites of 2–5 nm are formed. Iron oxyhydroxide nanoparticles strongly entrapped in PEI structure are obtained. The low and distributed values of the specific spontaneous magnetisation in samples prepared under the same pressure conditions support the presence of very fine FeO(OH) nanoparticles, which formation and magnetic properties are depending on the mass ratio between iron oxide and PEI. - Highlights: • Polyethyleneimine (PEI) – iron oxide hybrids were synthesized by hydrothermal method. • Synthesis parameters influence thermal stability and morphology of the hybrids. • Small crystallites of FeO(OH) with size between 2 and 5 nm are formed. • Formation of stable hybrid nanostructures in the pressure range 1000–3000 atm. • FeO(OH) nanoparticles are entrapped in PEI structure at low inorganic–organic ratio.

  2. Qualitative Assessment of the Symptoms and Impact of Pancreatic Exocrine Insufficiency (PEI) to Inform the Development of a Patient-Reported Outcome (PRO) Instrument.

    Science.gov (United States)

    Johnson, Colin D; Arbuckle, Rob; Bonner, Nicola; Connett, Gary; Dominguez-Munoz, Enrique; Levy, Philippe; Staab, Doris; Williamson, Nicola; Lerch, Markus M

    2017-03-22

    Pancreatic exocrine insufficiency (PEI) affects patients with chronic pancreatitis (CP) and cystic fibrosis (CF) who produce insufficient digestive pancreatic enzymes. Common symptoms include steatorrhoea, diarrhea, and abdominal pain. The objective of the study was to develop and test the content validity of a patient-reported outcome (PRO) instrument assessing PEI symptoms and their impact on health-related quality of life. Instrument development was supported by a literature review, expert physician interviews (n = 10: Germany 4, UK 3, France 3), and exploratory, qualitative, concept-elicitation interviews with patients with CF and CP with PEI (n = 61: UK 29, Germany 18, France 14) and expert physicians (n = 10). Cognitive debriefing of the draft instrument was then performed with patients with PEI (n = 37: UK 24, Germany 8, France 5), and feasibility was assessed with physicians (n = 3). For all interviews, verbatim transcripts were qualitatively analysed using thematic analysis methods and Atlas.ti computerized qualitative software. All themes were data driven rather than a priori. Patient interviews elicited symptoms and impacts not reported in the literature. Six symptom concepts emerged: pain, bloating, bowel symptoms, nausea/vomiting, eating problems, and tiredness/fatigue. Six impact domains were also identified. A 45-item instrument was developed in English, French, and German for testing in cognitive debriefing patient interviews. Following cognitive debriefing, 18 items were deleted. Rigorous qualitative patient research and expert clinical input supported development of a PEI-specific PRO with the potential to aid management and monitoring of unmet needs among patients with PEI. The next step is to perform psychometric evaluation of the resulting instrument.

  3. Spatiotemporal characterization of hydration process of asymmetric polymeric wound dressings for decubitus ulcers.

    Science.gov (United States)

    Górska, Anna; Dorożyński, Przemyslaw; Węglarz, Władysław P; Jasiński, Krzysztof; Kurek, Mateusz; Jachowicz, Renata; Klaja, Jolanta; Kulinowski, Piotr

    2017-04-13

    Pressure ulcers belong to the most chalenging clinical problems. As hydration level of such wounds is important for optimal healing, preparation of new wound dressing (WD) materials for pressure ulcers requires thorough in vitro evaluation as prerequisite to final in vivo testing. The aims of the study were to: (a) develop a simple method of preparation of asymmetric polymeric membrane, (b) to propose a set of in vitro methods for membrane characterization during hydration. A polyvinyl alcohol asymmetric membrane with homogeneous skin layer and porous spongy layer was developed with nonadhesive properties and ability to absorb and retain the water. Complementary methods, including magnetic resonance imaging, allowed quantitative assessment of spatiotemporal aspects of membrane hydration, that is, global water uptake; swelling; local hydration in terms of proton density mapping; spatial distribution of T2 relaxation time; Young's modulus; piercing resistance. The proposed method of initial wound dressing evaluation seems to be promising to compare various WD formulations, to assess the time required to prepare WD membrane to be applied to the wound and to assess how long WD retains desired working properties. The developed asymmetric membrane seems to be a good candidate for further evaluation. It was found that: Young's modulus of hydrated membrane was comparable to those of human skin; asymmetrical structure was retained during the entire hydration period; each layer had its own distinct, hydration related, properties and their spatiotemporal evolution; relatively slow changes of membrane properties during the potential WD application time-span of several hours was observed. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2017. © 2017 Wiley Periodicals, Inc.

  4. SEISMIC STUDIES OF MARINE GAS HYDRATES

    Institute of Scientific and Technical Information of China (English)

    SONG Haibin

    2003-01-01

    We give a brief introduction of developments of seismic methods in the studies of marine gas hydrates. Then we give an example of seismic data processing for BSRs in western Nankai accretionary prism, a typical gas hydrate distribution region. Seismic data processing is proved to be important to obtain better images of BSRs distribution. Studies of velocity structure of hydrated sediments are useful for better understanding the distribution of gas hydrates. Using full waveform inversion, we successfully derived high-resolution velocity model of a double BSR in eastern Nankai Trough area. Recent survey and research show that gas hydrates occur in the marine sediments of the South China Sea and East China Sea.But we would like to say seismic researches on gas hydrate in China are very preliminary.

  5. Development of Alaskan gas hydrate resources

    Energy Technology Data Exchange (ETDEWEB)

    Kamath, V.A.; Sharma, G.D.; Patil, S.L.

    1991-06-01

    The research undertaken in this project pertains to study of various techniques for production of natural gas from Alaskan gas hydrates such as, depressurization, injection of hot water, steam, brine, methanol and ethylene glycol solutions through experimental investigation of decomposition characteristics of hydrate cores. An experimental study has been conducted to measure the effective gas permeability changes as hydrates form in the sandpack and the results have been used to determine the reduction in the effective gas permeability of the sandpack as a function of hydrate saturation. A user friendly, interactive, menu-driven, numerical difference simulator has been developed to model the dissociation of natural gas hydrates in porous media with variable thermal properties. A numerical, finite element simulator has been developed to model the dissociation of hydrates during hot water injection process.

  6. In silico studies of the properties of water hydrating a small protein

    Science.gov (United States)

    Sinha, Sudipta Kumar; Jana, Madhurima; Chakraborty, Kausik; Bandyopadhyay, Sanjoy

    2014-12-01

    Atomistic molecular dynamics simulation of an aqueous solution of the small protein HP-36 has been carried out with explicit solvent at room temperature. Efforts have been made to explore the influence of the protein on the relative packing and ordering of water molecules around its secondary structures, namely, three α-helices. The calculations reveal that the inhomogeneous water ordering and density distributions around the helices are correlated with their relative hydrophobicity. Importantly, we have identified the existence of a narrow relatively dehydrated region containing randomly organized "quasi-free" water molecules beyond the first layer of "bound" waters at the protein surface. These water molecules with relatively weaker binding energies form the transition state separating the "bound" and "free" water molecules at the interface. Further, increased contribution of solid-like caging motions of water molecules around the protein is found to be responsible for reduced fluidity of the hydration layer. Interestingly, we notice that the hydration layer of helix-3 is more fluidic with relatively higher entropy as compared to the hydration layers of the other two helical segments. Such characteristics of helix-3 hydration layer correlate well with the activity of HP-36, as helix-3 contains the active site of the protein.

  7. Terahertz Time Domain Spectroscopy for Structure-II Gas Hydrates

    DEFF Research Database (Denmark)

    Takeya, Kei; Zhang, Caihong; Kawayama, Iwao

    2009-01-01

    For the nondestructive inspection of gas hydrates, terahertz (THz) time-domain spectroscopy (TDS) was applied to tetrahydrofuran (THF) hydrate and propane hydrate. The absorption of propane hydrate monotonically increases with frequency, similar to the case of ice, while THF hydrate has a charact...

  8. Clinker mineral hydration at reduced relative humidities

    DEFF Research Database (Denmark)

    Jensen, Ole Mejlhede

    1998-01-01

    This report deals with gas phase hydration of pure cement clinker minerals at reduced relative humidities. This is an important subject in relation to modern high performance concrete which may self-desiccate during hydration. In addition the subject has relevance to storage stability where...... prehydration may occur. In the report both theoretical considerations and experimental data are presented. It is suggested that the initiation of hydration during water vapour exposure is nucleation controlled....

  9. From Black Hole to Hydrate Hole: Gas hydrates, authigenic carbonates and vent biota as indicators of fluid migration at pockmark sites of the Northern Congo Fan

    Science.gov (United States)

    Kasten, S.; Schneider, R.; Spiess, V.; Cruise Participants Of M56b

    2003-04-01

    A recent high-resolution seismic, echosounder and video survey combined with detailed geological and geochemical sampling of pockmark sites on the Northern Congo Fan was carried out with RV Meteor in November/December 2002 in the frame of the project "CONGO" (BMBF/BEO "Geotechnologien"). These investigations revealed the extensive occurrence of surface and sub-surface gas hydrates as well as characteristic features of fluid venting such as clams (Calyptogena), tube worms (Pogonophera) and huge amounts of authigenic carbonates. In a first approach the patchyness in the occurrence of these features was mapped in relation to pockmark structure and seismic reflectors. Detailed sampling of three pockmarks by gravity corer showed that gas hydrates are present at and close to the sediment surface and often occur as several distinct layers and/or veins intercalated with hemipelagic muds. The depth of the upper boundary of these hydrate-bearing sediments increases from the center towards the edge of the pockmark structures. Pore water concentration profiles of sulfate and methane document the process of anaerobic methane oxidation above the hydrate-bearing layers. For those cores which contained several gas hydrate layers preliminary pore water profiles suggest the occurrence of more than one zone of anaerobic methane oxidation. Authigenic carbonates are found in high abundance, irregularly distributed within the pockmarks close to the sediment surface. These carbonates occur in a wide variety with respect to size, shape, structure and mineralogy. Their formation is associated with high amounts of bicarbonate released by the process of anaerobic methane oxidation. In the gravity cores authigenic carbonates are always present above hydrate-bearing sections. However, the quantities and characteristics of these authigenic minerals in relation to venting and microbial activity as well as to gas hydrate dissociation are not clear yet. Unraveling this relationship will be a major

  10. Polyethylenimine Interfacial Layers in Inverted Organic Photovoltaic Devices: Effects of Ethoxylation and Molecular Weight on Efficiency and Temporal Stability.

    Science.gov (United States)

    Courtright, Brett A E; Jenekhe, Samson A

    2015-12-02

    We report a comparative study of polyethylenimine (PEI) and ethoxylated-polyethylenimine (PEIE) cathode buffer layers in high performance inverted organic photovoltaic devices. The work function of the indium-tin oxide (ITO)/zinc oxide (ZnO) cathode was reduced substantially (Δφ = 0.73-1.09 eV) as the molecular weight of PEI was varied from 800 g mol(-1) to 750 000 g mol(-1) compared with the observed much smaller reduction when using a PEIE thin film (Δφ = 0.56 eV). The reference inverted polymer solar cells based on the small band gap polymer PBDTT-FTTE (ITO/ZnO/PBDTT-FTTE:PC70BM/MoO3/Ag), without a cathode buffer layer, had an average power conversion efficiency (PCE) of 6.06 ± 0.22%. Incorporation of a PEIE cathode buffer layer in the same PBDTT-FTTE:PC70BM blend devices gave an enhanced performance with a PCE of 7.37 ± 0.53%. In contrast, an even greater photovoltaic efficiency with a PCE of 8.22 ± 0.10% was obtained in similar PBDTT-FTTE:PC70BM blend solar cells containing a PEI cathode buffer layer. The temporal stability of the inverted polymer solar cells was found to increase with increasing molecular weight of the cathode buffer layer. The results show that PEI is superior to PEIE as a cathode buffer layer in high performance organic photovoltaic devices and that the highest molecular weight PEI interlayer provides the highest temporal stability.

  11. Prediction of Refrigerant Gas Hydrates Formation Conditions

    Institute of Scientific and Technical Information of China (English)

    Deqing Liang; Ruzhu Wang; Kaihua Guo; Shuanshi Fan

    2001-01-01

    A fugacity model was developed for prediction of mixed refrigerant gas hydrates formation conditions based on the molecule congregation and solution theories. In this model, g as hydrates were regarded as non-ideal solid solution composed of water groups and guest molecules, and the expressions of fugacity of guest molecules in hydrate phase was proposed accordingly. It has been shown that the developed model can indicate successfully the effect of guest-guest molecule interaction. The results showed that the model can describe better the characteristics of phase equilibrium of mixed refrigerant gas hydrates and predictions are in good agreement with experimental data.

  12. Desalination utilizing clathrate hydrates (LDRD final report).

    Energy Technology Data Exchange (ETDEWEB)

    Simmons, Blake Alexander; Bradshaw, Robert W.; Dedrick, Daniel E.; Cygan, Randall Timothy (Sandia National Laboratories, Albuquerque, NM); Greathouse, Jeffery A. (Sandia National Laboratories, Albuquerque, NM); Majzoub, Eric H. (University of Missouri, Columbia, MO)

    2008-01-01

    Advances are reported in several aspects of clathrate hydrate desalination fundamentals necessary to develop an economical means to produce municipal quantities of potable water from seawater or brackish feedstock. These aspects include the following, (1) advances in defining the most promising systems design based on new types of hydrate guest molecules, (2) selection of optimal multi-phase reactors and separation arrangements, and, (3) applicability of an inert heat exchange fluid to moderate hydrate growth, control the morphology of the solid hydrate material formed, and facilitate separation of hydrate solids from concentrated brine. The rate of R141b hydrate formation was determined and found to depend only on the degree of supercooling. The rate of R141b hydrate formation in the presence of a heat exchange fluid depended on the degree of supercooling according to the same rate equation as pure R141b with secondary dependence on salinity. Experiments demonstrated that a perfluorocarbon heat exchange fluid assisted separation of R141b hydrates from brine. Preliminary experiments using the guest species, difluoromethane, showed that hydrate formation rates were substantial at temperatures up to at least 12 C and demonstrated partial separation of water from brine. We present a detailed molecular picture of the structure and dynamics of R141b guest molecules within water cages, obtained from ab initio calculations, molecular dynamics simulations, and Raman spectroscopy. Density functional theory calculations were used to provide an energetic and molecular orbital description of R141b stability in both large and small cages in a structure II hydrate. Additionally, the hydrate of an isomer, 1,2-dichloro-1-fluoroethane, does not form at ambient conditions because of extensive overlap of electron density between guest and host. Classical molecular dynamics simulations and laboratory trials support the results for the isomer hydrate. Molecular dynamics simulations

  13. Role of electromechanical and mechanoelectric effects in protein hydration under hydrostatic pressure.

    Science.gov (United States)

    Danielewicz-Ferchmin, Irena; Banachowicz, Ewa M; Ferchmin, A Ryszard

    2011-10-21

    Recent measurements of lysozyme hydration water density under non-denaturing pressure show that it is higher than that of bulk water in the same conditions. High protein hydration layer density has earlier been observed at ambient conditions and ascribed to electrostriction. We calculate the pressure-induced protein mean surface charge density increment Δσ. Within the hydration layer, the higher fields due to Δσ lead to an additional water compression via electrostriction. The increment Δσ is considered as due to a mechanoelectric effect in protein molecules. The mean value of the effective mechanoelectric coefficient d is calculated and compared with piezoelectric coefficients of amino acids and their compounds. This journal is © the Owner Societies 2011

  14. Numerical studies of gas production from several CH4 hydrate zones at the Mallik site, Mackenzie Delta, Canada

    Science.gov (United States)

    Moridis, G.J.; Collett, T.S.; Dallimore, S.R.; Satoh, T.; Hancock, S.; Weatherill, B.

    2004-01-01

    The Mallik site represents an onshore permafrost-associated gas hydrate accumulation in the Mackenzie Delta, Northwest Territories, Canada. A gas hydrate research well was drilled at the site in 1998. The objective of this study is the analysis of various gas production scenarios from five methane hydrate-bearing zones at the Mallik site. In Zone #1, numerical simulations using the EOSHYDR2 model indicated that gas production from hydrates at the Mallik site was possible by depressurizing a thin free gas zone at the base of the hydrate stability field. Horizontal wells appeared to have a slight advantage over vertical wells, while multiwell systems involving a combination of depressurization and thermal stimulation offered superior performance, especially when a hot noncondensible gas was injected. Zone #2, which involved a gas hydrate layer with an underlying aquifer, could yield significant amounts of gas originating entirely from gas hydrates, the volumes of which increased with the production rate. However, large amounts of water were also produced. Zones #3, #4 and #5 were lithologically isolated gas hydrate-bearing deposits with no underlying zones of mobile gas or water. In these zones, thermal stimulation by circulating hot water in the well was used to induce dissociation. Sensitivity studies indicated that the methane release from the hydrate accumulations increased with the gas hydrate saturation, the initial formation temperature, the temperature of the circulating water in the well, and the formation thermal conductivity. Methane production appears to be less sensitive to the specific heat of the rock and of the hydrate, and to the permeability of the formation. ?? 2004 Published by Elsevier B.V.

  15. Influência da temperatura no desempenho mecânico de compósitos PEI/fibras de vidro Influence from the temperature on the mechanical behavior of PEI/glass fiber composites

    Directory of Open Access Journals (Sweden)

    Gustavo H. Oliveira

    2009-01-01

    Full Text Available Os compósitos poliméricos vêm ganhando grande destaque devido aos avanços tecnológicos conquistados pelas indústrias, principalmente a aeroespacial. Estes avanços têm como uma de várias finalidades a obtenção de compósitos com baixa massa específica associada às elevadas resistência mecânica e rigidez. Comparando os compósitos termoplásticos aos termorrígidos, pode ser destacado como suas principais vantagens: processamento mais rápido pela ausência de um ciclo de cura; baixa absorção de umidade; excelente resistência química; maior temperatura de serviço; baixo custo de transporte e estocagem; maior resistência ao impacto; maior rigidez e a possibilidade de serem reciclados. Devido às grandes variações de temperatura que estes materiais estão sujeitos durante sua vida útil como artefatos de aplicação aeronáutica, é de extrema importância a realização de estudos do seu comportamento mecânico a elevadas temperaturas, uma vez que a estas temperaturas as propriedades do compósito podem ser modificadas. O presente trabalho visa avaliar o comportamento mecânico (tração, fadiga e cisalhamento interlaminar, tanto em temperatura ambiente como a 80 °C de compósitos termoplásticos de matriz PEI (poli(éter-imida reforçados com fibras de vidro. Observou-se que os valores de resistências à tração, cisalhamento e fadiga do laminado PEI/fibras de vidro foram superiores aos encontrados para o laminado de epóxi/fibras de vidro. Entretanto, em todos os casos foram observadas quedas significativas nas propriedades mecânicas obtidas a 80 °C, em comparação com aquelas à temperatura ambiente.Polymeric composites have been used due to the technological progress in industries, mainly the aerospace. These advances are aimed at obtaining composites with low specific gravity associated with high mechanical properties and stiffness. The main advantages of thermoplastics over thermoset laminates include: fast

  16. Waters of Hydration of Cupric Hydrates: A Comparison between Heating and Absorbance Methods

    Science.gov (United States)

    Barlag, Rebecca; Nyasulu, Frazier

    2011-01-01

    The empirical formulas of four cupric hydrates are determined by measuring the absorbance in aqueous solution. The Beer-Lambert Law is verified by constructing a calibration curve of absorbance versus known Cu[superscript 2+](aq) concentration. A solution of the unknown hydrate is prepared by using 0.2-0.3 g of hydrate, and water is added such…

  17. Hydration in soccer: a review

    Directory of Open Access Journals (Sweden)

    Monteiro Cristiano Ralo

    2003-01-01

    Full Text Available Hydration should be considered before, during and after the exercise. This review intends to approach the main points of hydration process in soccer. The replacement of fluids during exercise is proportional to some factors, such as: exercise intensity; climatic conditions; the athlete's acclimatization; the athlete's physical conditioning; physiologic individual characteristics and the player's biomechanics. Performance is improved when players ingest not only water but also carbohydrate. The rates that carbohydrate and water are absorbed by the organism are limited by the rates of gastric emptying and intestinal absorption. The composition of drinks offered to the players should be influenced by the relative importance of the need of supplying carbohydrates or water; it should be remembered that the depletion of carbohydrate can result in fatigue and decrease of performance, but it is not usually a life-threatening condition. The addition of carbohydrate in these drinks increases the concentrations of blood glucose, increases the use of external fuel through the increase of the glucose oxidation in the muscles and it spares muscle glycogen. So, the ingestion of carbohydrate before and during the exercise can delay the emergence of fatigue and increase the players' performance. Several tactics can be used to avoid dehydration, like hyperhydration before exercise and player's acclimatization. The ideal situation to restore the player's fluid losses is between the sessions of exercises. Since soccer is a sport with quite peculiar characteristics related to hydration, the players should be concerned and educated about the importance of fluid ingestion before, during and after the exercise.

  18. X-ray computed-tomography observations of water flow through anisotropic methane hydrate-bearing sand

    Energy Technology Data Exchange (ETDEWEB)

    Seol, Yongkoo; Kneafsey, Timothy J.

    2009-06-01

    We used X-ray computed tomography (CT) to image and quantify the effect of a heterogeneous sand grain-size distribution on the formation and dissociation of methane hydrate, as well as the effect on water flow through the heterogeneous hydrate-bearing sand. A 28 cm long sand column was packed with several segments having vertical and horizontal layers with sands of different grain-size distributions. During the hydrate formation, water redistribution occurred. Observations of water flow through the hydrate-bearing sands showed that water was imbibed more readily into the fine sand, and that higher hydrate saturation increased water imbibition in the coarse sand due to increased capillary strength. Hydrate dissociation induced by depressurization resulted in different flow patterns with the different grain sizes and hydrate saturations, but the relationships between dissociation rates and the grain sizes could not be identified using the CT images. The formation, presence, and dissociation of hydrate in the pore space dramatically impact water saturation and flow in the system.

  19. Protein dynamics: hydration and cavities

    Directory of Open Access Journals (Sweden)

    K. Heremans

    2005-08-01

    Full Text Available The temperature-pressure behavior of proteins seems to be unique among the biological macromolecules. Thermodynamic as well as kinetic data show the typical elliptical stability diagram. This may be extended by assuming that the unfolded state gives rise to volume and enthalpy-driven liquid-liquid transitions. A molecular interpretation follows from the temperature and the pressure dependence of the hydration and cavities. We suggest that positron annihilation spectroscopy can provide additional quantitative evidence for the contributions of cavities to the dynamics of proteins. Only mature amyloid fibrils that form from unfolded proteins are very resistant to pressure treatment.

  20. Versatile dual organic interface layer for performance enhancement of polymer solar cells

    Science.gov (United States)

    Li, Zhiqi; Liu, Chunyu; Zhang, Zhihui; Li, Jinfeng; Zhang, Liu; Zhang, Xinyuan; Shen, Liang; Guo, Wenbin; Ruan, Shengping

    2016-11-01

    The electron transport layer plays a crucial role on determining electron injection and extraction, resulting from the effect of balancing charge transport and reducing the interfacial energy barrier. Decreasing the inherent incompatibility and enhancing electrical contact via employing appropriate buffer layer at the surface of hydrophobic organic active layer and hydrophilic inorganic electrode are also essential for charge collection. Herein, we demonstrate that an efficient dual polyelectrolytes interfacial layer composed of polyethylenimine (PEI) and conducting poly(9,9-dihexylfluorenyl-2,7-diyl) (PDHFD) is incorporated to investigate the interface energetics and electron transport in polymer solar cells (PSCs). The composited PEI/PDHFD interface layer (PPIL) overcomed the low conductivity of bare PEI polymer, which decreased series resistance and facilitated electron extraction at the ITO/PPIL-active layer interface. The introduction of the interface energy state of the PPIL reduced the work function of ITO so that it can mate the top of the valence band of the photoactive materials and promoted the formation of ohmic contact at ITO electrode interface. As a result, the composited PPIL tuned energy alignment and accelerated the electron transfer, leading to significantly increased photocurrent and power conversion efficiency (PCE) of the devices based on various representative polymer:fullerene systems.

  1. Formation rate of natural gas hydrate

    Energy Technology Data Exchange (ETDEWEB)

    Mork, Marit

    2002-07-01

    The rate of methane hydrate and natural gas hydrate formation was measured in a 9.5 litre stirred tank reactor of standard design. The experiments were performed to better understand the performance and scale-up of a reactor for continuous production of natural gas hydrates. The hydrate formation rate was measured at steady-state conditions at pressures between 70 and 90 bar and temperatures between 7 and 15 deg C. Between 44 and 56 % of the gas continuously supplied to the reactor was converted to hydrate. The experimental results show that the rate of hydrate formation is strongly influenced by gas injection rate and pressure. The effect of stirring rate is less significant and subcooling has no observable effect on the formation rate. Hydrate crystal concentration and gas composition do not influence the hydrate formation rate. Observations of produced hydrate crystals indicate that the crystals are elongated, about 5 micron in diameter and 10 micron long. Analysis of the results shows that the rate of hydrate formation is dominated by gas-liquid mass transfer. A mass transfer model, the bubble-to-crystal model, was developed for the hydrate formation rate in a continuous stirred tank reactor, given in terms of concentration driving force and an overall mass transfer coefficient. The driving force is the difference between the gas concentration at the gas-liquid interface and at the hydrate crystal surface. These concentrations correspond to the solubility of gas in water at experimental temperature and pressure and the solubility of gas at hydrate equilibrium temperature and experimental pressure, respectively. The overall mass transfer coefficient is expressed in terms of superficial gas velocity and impeller power consumption, parameters commonly used in study of stirred tank reactors. Experiments and modeling show that the stirred tank reactor has a considerable potential for increased production capacity. However, at higher hydrate production rates the

  2. Identification of a mechanism of transformation of clathrate hydrate structures I to II or H.

    Science.gov (United States)

    Yoshioki, Shuzo

    2012-07-01

    Binary mixed-gas hydrates including methane and other guest gases demonstrate a structural transition between the sI and sII phases. Under increasing pressure pure methane hydrate exhibits a phase transition first from sI to sII and then to sH. But the mechanism of the transformation from sI to sII or sH has not yet been identified. Recently, molecular dynamics simulations of methane hydrates suggest there may exist uncommon 15-hedral cages (5¹²6³), linking the sI and sII cages. In addition, xenon hydrate involving 15-hedral cages has been synthesized and named an hsI hydrate. Based on the hsI cages, we propose a mechanism for the transition of sI to sII or sH at atomic level resolution. The sI hydrate is first transformed to hsI, and hsI is further transformed to sII. Upon compression, hsI is transformed to sH owing to depletion of atomic layers. The mechanism of transformation speculated here calls for experimental verification.

  3. Simulation experiments on gas production from hydrate-bearing sediments

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Experiments were made on 58 sediment samples from four sites(1244,1245,1250 and 1251) of ODP204 at five temperature points(25,35,45,55 and 65℃) to simulate methane production from hydrate-bearing sediments.Simulation results from site 1244 show that the gas components consist mainly of methane and carbon dioxide,and heavy hydrocarbons more than C2+ cannot be detected.This site also gives results,similar to those from the other three,that the methane production is controlled by experimental temperatures,generally reaching the maximum gas yields per gram sediment or TOC under lower temperatures(25 and 35 ℃).In other words,the methane amount could be related to the buried depth of sediments,given the close relation between the depth and temperature.Sediments less than 1200 m below seafloor are inferred to still act as a biogenic gas producer to pour methane into the present hydrate zone,while sedimentary layers more than 1200 m below seafloor have become too biogenically exhausted to offer any biogas,but instead they produce thermogenic gas to give additional supply to the hydrate formation in the study area.

  4. Hydration and Nanoconfined Water: Insights from Computer Simulations.

    Science.gov (United States)

    Alarcón, Laureano M; Rodríguez Fris, J A; Morini, Marcela A; Sierra, M Belén; Accordino, S A; Montes de Oca, J M; Pedroni, Viviana I; Appignanesi, Gustavo A

    2015-01-01

    The comprehension of the structure and behavior of water at interfaces and under nanoconfinement represents an issue of major concern in several central research areas like hydration, reaction dynamics and biology. From one side, water is known to play a dominant role in the structuring, the dynamics and the functionality of biological molecules, governing main processes like protein folding, protein binding and biological function. In turn, the same principles that rule biological organization at the molecular level are also operative for materials science processes that take place within a water environment, being responsible for the self-assembly of molecular structures to create synthetic supramolecular nanometrically-sized materials. Thus, the understanding of the principles of water hydration, including the development of a theory of hydrophobicity at the nanoscale, is imperative both from a fundamental and an applied standpoint. In this work we present some molecular dynamics studies of the structure and dynamics of water at different interfaces or confinement conditions, ranging from simple model hydrophobic interfaces with different geometrical constraints (in order to single out curvature effects), to self-assembled monolayers, proteins and phospholipid membranes. The tendency of the water molecules to sacrifice the lowest hydrogen bond (HB) coordination as possible at extended interfaces is revealed. This fact makes the first hydration layers to be highly oriented, in some situations even resembling the structure of hexagonal ice. A similar trend to maximize the number of HBs is shown to hold in cavity filling, with small subnanometric hydrophobic cavities remaining empty while larger cavities display an alternation of filled and dry states with a significant inner HB network. We also study interfaces with complex chemical and geometrical nature in order to determine how different conditions affect the local hydration properties. Thus, we show some

  5. Layer-by-layer assembled carbon nanotube-acetylcholinesterase/biopolymer renewable interfaces: SPR and electrochemical characterization.

    Science.gov (United States)

    Zhang, Yuanyuan; Arugula, Mary A; Kirsch, Jeffrey S; Yang, Xiaoyun; Olsen, Eric; Simonian, Aleksandr L

    2015-02-03

    Developing simple, reliable, and cost-effective methods of renewing an inhibited biocatalyst (e.g., enzymatic interfaces) on biosensors is needed to advance multiuse, reusable sensor applications. We report a method for the renewal of layer-by-layer (LbL) self-assembled inhibition-based enzymatic interfaces in multiwalled carbon nanotube (MWCNT) armored acetylcholinesterase (AChE) biosensors. The self-assembly process of MWCNT dispersed enzymes/biopolymers was investigated using surface plasmon resonance (SPR). The LbL fabrication consisted of alternating cushion layers of positively charged CNT-polyethylenimine (CNT-PEI) and negatively charged CNT-deoxyribonucleic acid (CNT-DNA) and a functional interface consisting of alternating layers of CNT-PEI and negatively charged CNT-acetylcholine esterase (CNT-AChE, pH 7.4). The observed SPR response signal increased while assembling the different layers, indicating the buildup of multiple layers on the Au surface. A partial desorption of the top enzymatic layer in the LbL structure was observed with a desorption strategy employing alkaline treatment. This indicates that the strong interaction of CNT-biopolymer conjugates with the Au surface was a result of both electrostatic interactions between biopolymers and the surface binding energy from CNTs: the closer the layers are to the Au surface, the stronger the interactions. In contrast, a similar LbL assembly of soluble enzyme/polyelectrolytes resulted in stronger desorption on the surface after the alkaline treatment; this led to the investigation of AChE layer removal, permanently inhibited after pesticide exposure on glassy carbon (GC) electrodes, while keeping the cushion layers intact. The desorption strategy permitted the SPR and electrochemical electrode surfaces to be regenerated multiple times by the subsequent self-assembly of fresh PEI/AChE layers. Flow-mode electrochemical amperometric analysis demonstrated good stability toward the determination of

  6. Ergonomic Analysis of UI’s BicyclesUsing Posture Evaluation Index (PEI Method in Virtual Environment

    Directory of Open Access Journals (Sweden)

    Erlinda Muslim

    2010-10-01

    Full Text Available This research was conducted to study ergonomic aspect from University of Indonesia bicycle in virtual environment. Software Jack 6.0 was used to analyze it. PEI was used as approach that integrated the results of three methods: Lower Back Analysis, Ovako Working Posture Analysis, and Rapid Upper Limb Assessment. The research objective is to evaluate existing design of University of Indonesia bicycle and to determine the most ergonomic redesign which concern with handlebar height and saddle height modification. The result showed that the most ergonomic design of University of Indonesia bicycle is the one with the highest handlebar height (22 cm and the lowest saddle height (11 cm.

  7. Involvement of canine oral papillomavirus in generalized oral and cutaneous verrucosis in a Chinese Shar Pei dog.

    Science.gov (United States)

    Sundberg, J P; Smith, E K; Herron, A J; Jenson, A B; Burk, R D; Van Ranst, M

    1994-03-01

    Severe papillomatosis developed in the oral cavity and spread throughout the haired skin of the trunk and limbs of an 8-month-old female Chinese Shar Pei dog. The dog had received corticosteroids prior to referral, which was associated with the onset of demodecosis and papillomatosis. Papillomavirus structural antigens were detected in biopsies by immunohistochemistry using a panel of monoclonal and polyclonal antibodies. An 8.2-kilobase papillomavirus-specific DNA molecule was detected in the cutaneous lesions by high stringency Southern blot hybridization using a cloned canine oral papillomavirus DNA probe. Restriction enzyme analysis revealed that the virus in the cutaneous lesions was identical to the canine oral papillomavirus. Discontinuation of the steroids combined with the use of a mitocide, antibiotics, and an autogenous vaccine resolved the demodecosis and papillomatosis. This case report suggests that corticosteroid-induced immunosuppression can expand the tissue tropism of papillomaviruses.

  8. Two-Sided Surface Oxidized Cellulose Membranes Modified with PEI: Preparation, Characterization and Application for Dyes Removal

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2017-09-01

    Full Text Available Porous regenerated cellulose (RC membranes were prepared with cotton linter pulp as a raw material. These membranes were first oxidized on both sides by a modified (2,2,6,6-tetramethylpiperidin-1-yloxyl (TEMPO oxidation system using a controlled oxidation reaction technique. Then, the oxidized RC membranes were functionalized with polyethylenimine (PEI via the glutaraldehyde crosslinking method to obtain bifunctional (carboxyl and amino porous RC membranes, as revealed by Fourier transform infrared spectroscopy (FT-IR, elemental analysis and zeta potential measurement. The scanning electron microscopy (SEM and the tests of the mechanical properties and permeability characteristics of modified RC membranes demonstrated that the porous structure and certain mechanical properties could be retained. The adsorption performance of the modified membranes towards dyes was subsequently investigated. The modified membranes displayed good adsorption capacities, rapid adsorption equilibrium and removal efficiencies towards both anionic (xylenol orange (XO and cationic (methylene blue (MB dyes, making them suitable bioadsorbents for wastewater treatment.

  9. O ENVELHECIMENTO, A DOENÇA DE ALZHEIMER E AS CONTRIBUIÇÕES DO PROGRAMA DE ENRIQUECIMENTO INSTRUMENTAL (PEI

    Directory of Open Access Journals (Sweden)

    Antonia Rozeli Roberto de Oliveira

    2010-06-01

    Full Text Available This article suggests that the aging process has unique and distinct features. A distinction is made between normal and pathological aging. Actually we are concerned that a successful aging is in close relationship with the pre-vention of diseases, and maintenance of physical and cognitive activities. Epidemiological studies show that elderly people with mild cognitive deficts are at greater risk of developing Alzheimer's disease. This disease affects brain function, primarily memory, and also speech, executive functions, praxias and gnosias. Besides the current pharmacological approach, alterna-tive therapies, like neuropsychological rehabilitation, are in current use and contributes in a great amount to the improvement of cognitive and behav-ioral functions. In this article we gave special attention using PEI and EAM, in neuropsychological rehabilitation programs directed to Alzheimer`s dis-ease, focusing the improvement of residual functions and aiming the reduc-tion of the impact that this disease brings to the quality of life.

  10. Nano-TiO2 reinforced PEEK/PEI blends as biomaterials for load-bearing implant applications.

    Science.gov (United States)

    Díez-Pascual, Ana M; Díez-Vicente, Angel L

    2015-03-11

    Biocompatible ternary nanocomposites based on poly(ether ether ketone) (PEEK)/poly(ether imide) (PEI) blends reinforced with bioactive titanium dioxide (TiO2) nanoparticles were fabricated via ultrasonication followed by melt-blending. The developed biomaterials were characterized using FT-IR, SEM, XRD, DSC, TGA, and DMA. Further, their water-absorption, tensile, tribological, dielectric, and antibacterial properties were evaluated. PEI acts as a coupling agent, since it can interact both with PEEK via π-π stacking and polar interactions as well as with the nanoparticles through hydrogen bonding, as corroborated by the FT-IR spectra, which resulted in a homogeneous titania dispersion within the biopolymer blend without applying any particle surface treatment or polymer functionalization. A change from promotion to retardation in the crystallization rate of the matrix was found with increasing TiO2 concentration, while its crystalline structure remained unaltered. The nanoparticles stiffened, strengthened, and toughened the matrix simultaneously, and the optimal properties were achieved at 4.0 wt % TiO2. More interesting, the tensile properties were retained after steam sterilization in an autoclave or exposure to a simulated body fluid (SBF). The nanocomposites also displayed reduced water absorption though higher thermal stability, storage modulus, glass transition temperature, dielectric constant, and dielectric loss compared to the control blend. Further, remarkable enhancements in the tribological properties under both SBF and dry environments were attained. The nanoparticles conferred antibacterial action versus Gram-positive and Gram-negative bacteria in the presence and the absence of UV light, and the highest inhibition was attained at 4.0 wt % nanoparticle concentration. These nanocomposites are expected to be used in long-term load-bearing implant applications.

  11. Structural alterations of fully hydrated human stratum corneum

    Energy Technology Data Exchange (ETDEWEB)

    Charalambopoulou, G.Ch.; Steriotis, Th.A.; Hauss, Th.; Stubos, A.K.; Kanellopoulos, N.K

    2004-07-15

    The diffusional barrier function of skin is associated with the superficial epidermal layer, the stratum corneum, a highly complex biomembrane consisting of a staggered corneocyte arrangement in a lipid lamellar continuum. One of the key elements for stratum corneum barrier function is its hydration state. In the present work, the membrane neutron diffraction method is employed to reveal important stratum corneum structural changes that emanate upon water uptake. Increasing stratum corneum water content was observed to lead reversibly to the progressive disruption of the highly ordered lipid configuration and the distortion of the system's barrier functio000.

  12. Fabrication of Core-Shell PEI/pBMP2-PLGA Electrospun Scaffold for Gene Delivery to Periodontal Ligament Stem Cells

    Directory of Open Access Journals (Sweden)

    Qiao Xie

    2016-01-01

    Full Text Available Bone tissue engineering is the most promising technology for enhancing bone regeneration. Scaffolds loaded with osteogenic factors improve the therapeutic effect. In this study, the bioactive PEI (polyethylenimine/pBMP2- (bone morphogenetic protein-2 plasmid- PLGA (poly(D, L-lactic-co-glycolic acid core-shell scaffolds were prepared using coaxial electrospinning for a controlled gene delivery to hPDLSCs (human periodontal ligament stem cells. The pBMP2 was encapsulated in the PEI phase as a core and PLGA was employed to control pBMP2 release as a shell. First, the scaffold characterization and mechanical properties were evaluated. Then the gene release behavior was analyzed. Our results showed that pBMP2 was released at high levels in the first few days, with a continuous release behavior in the next 28 days. At the same time, PEI/pBMP2 showed high transfection efficiency. Moreover, the core-shell electrospun scaffold showed BMP2 expression for a much longer time (more than 28 days compared with the single axial electrospun scaffold, as evaluated by qRT-PCR and western blot after culturing with hPDLSCs. These results suggested that the core-shell PEI/pBMP2-PLGA scaffold fabricated by coaxial electrospinning had a good gene release behavior and showed a prolonged expression time with a high transfection efficiency.

  13. Elucidating the interplay between DNA-condensing and free polycations in gene transfection through a mechanistic study of linear and branched PEI

    DEFF Research Database (Denmark)

    Dai, Zhuojun; Gjetting, Torben; Mattebjerg, Maria Ahlm;

    2011-01-01

    In the present study we compare LPEI and BPEI characteristics related to DNA condensation and their role as free polycation chains in gene transfection. Using radioactive 32P labeled DNA, we investigated the effect of free PEI chains on the cellular uptake of polyplexes. Our investigations show d...

  14. Co-delivery of Doxorubicin Encapsulated PLGA Nanoparticles and Bcl-xL shRNA Using Alkyl-Modified PEI into Breast Cancer Cells.

    Science.gov (United States)

    Ebrahimian, Mahboubeh; Taghavi, Sahar; Mokhtarzadeh, Ahad; Ramezani, Mohammad; Hashemi, Maryam

    2017-02-24

    In recent years, much effort has been focused on an appropriate combination of chemotherapeutic drugs and nucleic acids to exploit additive or synergistic therapeutic effects and overcome many obstacles such as the reduction of side effects and drug resistance. Short hairpin RNA (shRNA) has designed to allow the production of small interfering RNA (siRNA) within the cells and offer long-lasting silencing of target genes. In this study, alkyl-modified polyethylenimine (PEI 10 kD) was used for co-delivery of doxorubicin (DOX) encapsulated into poly lactic-co-glycolic acid (PLGA) nanoparticles (NPs) and Bcl-xL shRNA (one class of molecules that block apoptosis of tumor cells) into breast cancer cells. Our results demonstrated that modification of PEI with alkyl chain could enhance the induction of apoptosis in tumor cells by suppression of Bcl-xL gene using Bcl-xL shRNA more than PEI alone. On the other hand, DOX encapsulated into PLGA had more synergistic effect with shRNA in comparison with DOX alone. In conclusion, combination of PLGA-DOX NPs and alkyl-PEI/shRNA complexes may have promising applications in breast cancer therapy.

  15. Dynamics of a photoexcited hydrated electron

    NARCIS (Netherlands)

    Pshenichnikov, M.S.; Baltuška, A.; Wiersma, D.A.; Kärtner, F.X.

    2004-01-01

    Combining photon-echo and frequency-resolved pump-probe techniques with extremely short laser pulses that consist of only few optical cycles, we investigate the dynamics of the equilibrated hydrated electron. The pure dephasing time of the hydrated electron deduced from the photon-echo measurements

  16. Gas hydrate inhibition of drilling fluid additives

    Energy Technology Data Exchange (ETDEWEB)

    Xiaolan, L.; Baojiang, S.; Shaoran, R. [China Univ. of Petroleum, Dongying (China). Inst. of Petroleum Engineering

    2008-07-01

    Gas hydrates that form during offshore well drilling can have adverse impacts on well operational safety. The hydrates typically form in the risers and the annulus between the casing and the drillstring, and can stop the circulation of drilling fluids. In this study, experiments were conducted to measure the effect of drilling fluid additives on hydrate inhibition. Polyalcohols, well-stability control agents, lubricating agents, and polymeric materials were investigated in a stirred tank reactor at temperatures ranging from -10 degree C to 60 degrees C. Pressure, temperature, and torque were used to detect onset points of hydrate formation and dissociation. The inhibitive effect of the additives on hydrate formation was quantified. Phase boundary shifts were measured in terms of temperature difference or sub-cooling gained when chemicals were added to pure water. Results showed that the multiple hydroxyl groups in polyalcohol chemicals significantly inhibited hydrate formation. Polymeric and polyacrylamide materials had only a small impact on hydrate formation, while sulfonated methyl tannins were found to increase hydrate formation. 6 refs., 1 tab., 4 figs.

  17. Hydration shells exchange charge with their protein

    DEFF Research Database (Denmark)

    Abitan, Haim; Lindgård, Per-Anker; Nielsen, Bjørn Gilbert;

    2010-01-01

    Investigation of the interaction between a protein and its hydration shells is an experimental and theoretical challenge. Here, we used ultrasonic pressure waves in aqueous solutions of a protein to explore the conformational states of the protein and its interaction with its hydration shells. In...

  18. A new geotechnical gas hydrates research laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Grozic, J.L.H. [Calgary Univ., AB (Canada)

    2003-07-01

    Gas hydrates encapsulate natural gas molecules in a very compact form, as ice-like compounds composed of water molecules. Permafrost environments and offshore areas contain vast quantities of gas hydrates within soil and rock. This paper describes the role played by gas hydrates in submarine slope instability, their potential as a sustainable energy source, and their effects on global climate change. A new state-of-the-art laboratory located at the University of Calgary, which was developed to study the geomechanical behaviour of gas hydrate-sediment mixtures, was also presented. A specialized high pressure low temperature triaxial apparatus capable of performing a suite of tests on gas hydrate-sediment mixtures is housed in this laboratory. Extensive renovations were required in order to enable the use of methane gas to simulate natural hydrate formation conditions. The laboratory is specifically designed to examine the properties and behaviour of reconstituted gas hydrate-sediment mixtures and natural gas hydrate core samples. 26 refs., 9 figs.

  19. Investigations into surfactant/gas hydrate relationship

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, Rudy; Zhang, Guochang; Dearman, Jennifer; Woods, Charles [Swalm School of Chemical Engineering, Mississippi State University, Mississippi State, MS 39762 (United States)

    2007-03-15

    Gas hydrates have unique physical properties portending useful industrial applications of gas storage, gas separation, or water desalination. When gas hydrates were found in the early 1990s to occur naturally and abundantly in seafloors, three other primary interests and concerns emerged: potential new energy source, climate threat from their greenhouse gases, and seafloor instabilities. This paper presents research showing how anionic synthetic surfactants helped develop an industrial gas hydrate storage process for natural gas and how naturally-occurring in-situ anionic biosurfactants influence the formation and placement of gas hydrates in ocean sediments. The catalytic effects, mechanisms, and surface specificities imparted by synthetic surfactants in the gas storage process and imparted by biosurfactants in porous media are discussed. The Bacillus subtilis bacterium that is indigenous to gas hydrate mounds in the Gulf of Mexico was cultured in the laboratory. Its biosurfactant was separated and found to catalyze gas hydrates in porous media. The experiments indicate that seafloor-biosurfactants can be produced rapidly in-situ to achieve threshold concentrations whereby hydrates are promoted. The biosurfactants accumulate and promote hydrate formation on specific mineral surfaces such as sodium montmorillonite. (author)

  20. Raman Spectroscopic Studies of Methane Gas Hydrates

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Berg, Rolf W.

    2009-01-01

    A brief review of the Raman spectroscopic studies of methane gas hydrates is given, supported by some new measurements done in our laboratory.......A brief review of the Raman spectroscopic studies of methane gas hydrates is given, supported by some new measurements done in our laboratory....

  1. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Donn McGuire; Steve Runyon; Richard Sigal; Bill Liddell; Thomas Williams; George Moridis

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. Hot Ice No. 1 was planned to test the Ugnu and West Sak sequences for gas hydrates and a concomitant free gas accumulation on Anadarko's 100% working interest acreage in section 30 of Township 9N, Range 8E of the Harrison Bay quadrangle of the North Slope of Alaska. The Ugnu and West Sak intervals are favorably positioned in the hydrate-stability zone over an area extending from Anadarko's acreage westward to the vicinity of the aforementioned gas-hydrate occurrences. This suggests that a large, north-to-south trending gas-hydrate accumulation may exist in that area. The presence of gas shows in the Ugnu and West Sak reservoirs in wells situated eastward and down dip of the Hot Ice location indicate that a free-gas accumulation may be trapped by gas hydrates. The Hot Ice No. 1 well was designed to core from the surface to the base of the West Sak interval using the

  2. Compound Natural Gas Hydrate: A Natural System for Separation of Hydrate-Forming Gases

    Science.gov (United States)

    Max, M. D.; Osegovic, J. P.

    2007-12-01

    Natural processes that separate materials from a mixture may exert a major influence on the development of the atmospheres and surfaces of planets, moons, and other planetary bodies. Natural distillation and gravity separation, amongst others, are well known means of differentiating materials through liquid-gas partitioning. One of the least known attributes of clathrate (gas) hydrates is their potential effect on the evolution of planetary system oceans and atmospheres. Gas hydrates separate gases from mixtures of gases by concentrating preferred hydrate-forming materials (HFM) guests within the water-molecule cage structure of crystalline hydrate. Different HFMs have very different fields of stability. When multiple hydrate formers are present, a preference series based on their selective uptake exists. Compound hydrate, which is formed from two or more species of HFM, extract preferred HFM from a mixture in very different proportions to their relative percentages of the original mixture. These compound hydrates can have different formation and dissociation conditions depending on the evolution of the environment. That is, the phase boundary of the compound hydrate that is required for dissociation lies along a lower pressure - higher temperature course. Compound hydrates respond to variations in temperature, pressure, and HFM composition. On Earth, the primary naturally occurring hydrate of interest to global climate modeling is methane hydrate. Oceanic hydrate on Earth is the largest store of carbon in the biosphere that is immediately reactive to environmental change, and is capable of releasing large amounts of methane into the atmosphere over a short geological time span. Hydrate formation is essentially metastable and is very sensitive to environmental change and to gas flux. Where natural variations in temperature and pressure varies so that hydrate will form and dissociate in some cyclical manner, such as in oceans where sea level is capable of rising and

  3. A novel unstable duplication upstream of HAS2 predisposes to a breed-defining skin phenotype and a periodic fever syndrome in Chinese Shar-Pei dogs.

    Directory of Open Access Journals (Sweden)

    Mia Olsson

    2011-03-01

    Full Text Available Hereditary periodic fever syndromes are characterized by recurrent episodes of fever and inflammation with no known pathogenic or autoimmune cause. In humans, several genes have been implicated in this group of diseases, but the majority of cases remain unexplained. A similar periodic fever syndrome is relatively frequent in the Chinese Shar-Pei breed of dogs. In the western world, Shar-Pei have been strongly selected for a distinctive thick and heavily folded skin. In this study, a mutation affecting both these traits was identified. Using genome-wide SNP analysis of Shar-Pei and other breeds, the strongest signal of a breed-specific selective sweep was located on chromosome 13. The same region also harbored the strongest genome-wide association (GWA signal for susceptibility to the periodic fever syndrome (p(raw = 2.3 × 10⁻⁶, p(genome = 0.01. Dense targeted resequencing revealed two partially overlapping duplications, 14.3 Kb and 16.1 Kb in size, unique to Shar-Pei and upstream of the Hyaluronic Acid Synthase 2 (HAS2 gene. HAS2 encodes the rate-limiting enzyme synthesizing hyaluronan (HA, a major component of the skin. HA is up-regulated and accumulates in the thickened skin of Shar-Pei. A high copy number of the 16.1 Kb duplication was associated with an increased expression of HAS2 as well as the periodic fever syndrome (p < 0.0001. When fragmented, HA can act as a trigger of the innate immune system and stimulate sterile fever and inflammation. The strong selection for the skin phenotype therefore appears to enrich for a pleiotropic mutation predisposing these dogs to a periodic fever syndrome. The identification of HA as a major risk factor for this canine disease raises the potential of this glycosaminoglycan as a risk factor for human periodic fevers and as an important driver of chronic inflammation.

  4. Flow injection chemiluminescence immunoassay of microcystin-LR by using PEI-modified magnetic beads as capturer and HRP-functionalized silica nanoparticles as signal amplifier.

    Science.gov (United States)

    Lu, Jusheng; Wei, Wei; Yin, Lihong; Pu, Yuepu; Liu, Songqin

    2013-03-07

    A rapid sandwiched immunoassay of microcystin-LR (MC-LR) in water is proposed with flow injection chemiluminescence detection. The magnetic beads (MBs) were first modified with polyethyleneimine (PEI) by acylamide bond between the carboxyl group on the surface of MBs and the primary amine group in PEI, followed by immobilizing of anti-MC-LR (Ab1) onto PEI with glutaraldehyde as linkage. The resulting Ab1 modified MBs captured the target MC-LR in water, reacted with the horseradish peroxidase and anti-MC-LR co-immobilized silica nanoparticles, and were detected with flow injection chemiluminescence. When using PEI/MBs as the carrier of anti-MC-LR, the CL signal was greatly enhanced up to 9-fold compared to that using MBs without PEI modification. The CL signal was further amplified 13-fold when Si/Ab2 was used as the signal probe. Under the optimal conditions, the present immunoassay exhibited a wide quantitative range from 0.02 to 200 μg L(-1) with a detection limit of 0.006 μg L(-1), which was much lower than the WHO provisional guideline limit of 1.0 μg L(-1) for MC-LR in drinking water. The relative standard deviation was 4.8% and the recoveries for the spiked samples ranged from 84% to 115%, which indicated acceptable precision and accuracy for MC-LR. The present method is easier to perform and less time-consuming (the entire analysis process lasted about 40 minutes) and has been applied to the detection of MC-LR in different water samples successfully.

  5. Effect of miR-146a/bFGF/PEG-PEI Nanoparticles on Inflammation Response and Tissue Regeneration of Human Dental Pulp Cells

    Directory of Open Access Journals (Sweden)

    Lu Liu

    2016-01-01

    Full Text Available Introduction. Inflammation in dental pulp cells (DPCs initiated by Lipopolysaccharide (LPS results in dental pulp necrosis. So far, whether there is a common system regulating inflammation response and tissue regeneration remains unknown. miR-146a is closely related to inflammation. Basic fibroblast growth factor (bFGF is an important regulator for differentiation. Methods. To explore the effect of miR-146a/bFGF on inflammation and tissue regeneration, polyethylene glycol-polyethyleneimine (PEG-PEI was synthesized, and physical characteristics were analyzed by dynamic light scattering and gel retardation analysis. Cell absorption, transfection efficiency, and cytotoxicity were assessed. Alginate gel was combined with miR-146a/PEG-PEI nanoparticles and bFGF. Drug release ratio was measured by ultraviolet spectrophotography. Proliferation and odontogenic differentiation of DPCs with 1 μg/mL LPS treatment were determined. Results. PEG-PEI prepared at N/P 2 showed complete gel retardation and smallest particle size and zeta potential. Transfection efficiency of PEG-PEI was higher than lipo2000. Cell viability decreased as N/P ratio increased. Drug release rate amounted to 70% at the first 12 h and then maintained slow release afterwards. Proliferation and differentiation decreased in DPCs with LPS treatment, whereas they increased in miR-146a/bFGF gel group. Conclusions. PEG-PEI is a promising vector for gene therapy. miR-146a and bFGF play critical roles in inflammation response and tissue regeneration of DPCs.

  6. Overview on Hydrate Coring, Handling and Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Jon Burger; Deepak Gupta; Patrick Jacobs; John Shillinglaw

    2003-06-30

    Gas hydrates are crystalline, ice-like compounds of gas and water molecules that are formed under certain thermodynamic conditions. Hydrate deposits occur naturally within ocean sediments just below the sea floor at temperatures and pressures existing below about 500 meters water depth. Gas hydrate is also stable in conjunction with the permafrost in the Arctic. Most marine gas hydrate is formed of microbially generated gas. It binds huge amounts of methane into the sediments. Worldwide, gas hydrate is estimated to hold about 1016 kg of organic carbon in the form of methane (Kvenvolden et al., 1993). Gas hydrate is one of the fossil fuel resources that is yet untapped, but may play a major role in meeting the energy challenge of this century. In June 2002, Westport Technology Center was requested by the Department of Energy (DOE) to prepare a ''Best Practices Manual on Gas Hydrate Coring, Handling and Analysis'' under Award No. DE-FC26-02NT41327. The scope of the task was specifically targeted for coring sediments with hydrates in Alaska, the Gulf of Mexico (GOM) and from the present Ocean Drilling Program (ODP) drillship. The specific subjects under this scope were defined in 3 stages as follows: Stage 1: Collect information on coring sediments with hydrates, core handling, core preservation, sample transportation, analysis of the core, and long term preservation. Stage 2: Provide copies of the first draft to a list of experts and stakeholders designated by DOE. Stage 3: Produce a second draft of the manual with benefit of input from external review for delivery. The manual provides an overview of existing information available in the published literature and reports on coring, analysis, preservation and transport of gas hydrates for laboratory analysis as of June 2003. The manual was delivered as draft version 3 to the DOE Project Manager for distribution in July 2003. This Final Report is provided for records purposes.

  7. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Bill Liddell

    2005-03-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Oil-field engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in Arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrates agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is a cost-shared partnership between Maurer Technology, Anadarko Petroleum, Noble Corporation, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to help identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. As part of the project work scope, team members drilled and cored the HOT ICE No. 1 on Anadarko leases beginning in January 2003 and completed in March 2004. Due to scheduling constraints imposed by the Arctic drilling season, operations at the site were suspended between April 21, 2003 and January 30, 2004. An on-site core analysis laboratory was designed, constructed and used for determining physical characteristics of frozen core immediately after it was retrieved from the well. The well was drilled from a new and innovative Anadarko Arctic Platform that has a greatly reduced footprint and environmental impact. Final efforts of the project were to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists for future hydrate operations. Unfortunately, no gas hydrates were encountered in this well; however, a wealth of information was generated

  8. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Buddy King

    2004-07-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The work scope drilled and cored a well The HOT ICE No.1 on Anadarko leases beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists developing reservoir models. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this report.

  9. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Buddy King

    2004-06-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the final stages of a cost shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The work scope drilled and cored a well The HOT ICE No.1 on Anadarko leases beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists developing reservoir models. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this report.

  10. Lithological controls on gas hydrate saturation: Insights from signal classification of NMR downhole data

    Science.gov (United States)

    Bauer, Klaus; Kulenkampff, Johannes; Henninges, Jan; Spangenberg, Erik

    2016-04-01

    Nuclear magnetic resonance (NMR) downhole data are analyzed with a new strategy to study gas hydrate-bearing sediments in the Mackenzie Delta (NW Canada). NMR logging is a powerful tool to study geological reservoir formations. The measurements are based on interactions between the magnetic moments of protons in geological formation water and an external magnetic field. Inversion of the measured raw data provides so-called transverse relaxation time (T2) distribution curves or spectra. Different parts of the T2 curve are related with distinct pore radii and corresponding fluid components. A common practice in the analysis of T2 distribution curves is to extract single-valued parameters such as apparent total porosity. Moreover, the derived total NMR apparent porosity and the gamma-gamma density log apparent porosity can be combined to estimate gas hydrate saturation in hydrate-bearing sediments. To avoid potential loss of information, in our new approach we analyze the entire T2 distribution curves as quasi-continuous signals to characterize the rock formation. The approach is applied to NMR data measured in gas hydrate research well Mallik 5L-38. We use self-organizing maps, a neural network clustering technique, to subdivide the data set of NMR T2 distribution curves into classes with a similar and distinctive signal shape. The method includes (1) preparation of data vectors, (2) unsupervised learning, (3) cluster definition, and (4) classification and depth mapping of all NMR signals. Each signal class thus represents a specific pore size distribution which can be interpreted in terms of distinct lithologies and reservoir types. A key step in the interpretation strategy is to reconcile the NMR classes with other log data not considered in the clustering analysis, such as gamma ray, photo-electric factor, hydrate saturation, and other logs. Our results defined six main lithologies within the target zone. Gas hydrate layers were recognized by their low signal

  11. Peptide isolated from Cry1Ab16 toxin present in Bacillus thuringiensis: Synthesis and morphology data for layer-by-layer films studied by atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Alexandra Plácido

    2016-09-01

    Full Text Available The peptide PcL342-354C was obtained from the Cry1Ab16 toxin present in Bacillus thuringiensis (“Computational Modeling Deduced Three Dimensional Structure of Cry1Ab16 Toxin from B. thuringiensis AC11” (Kashyap, 2012 [1]. In this data article, we report the synthesis and characterization of the PcL342-354C peptide by MALDI-TOF/TOF mass spectrometry. In addition, the preparation of layer-by-layer films is shown based on interspersion of this peptide with both polyethylenimine (PEI and poly(sodium 4-styrenesulfonate (PSS, self-assembled on ITO (indium tin oxide electrodes. The morphology of the ITO/PEI/PSS/PcL342-354C film was analyzed using atomic force microscopy (AFM. We also evaluated the effect of the number of bilayers in ITO/PEI/(PSS/PcL342-354Cn on the morphology of the film using AFM amplitude images. Further details about this study were published elsewhere, “Layer-by-layer films containing peptides of the Cry1Ab16 toxin from B. thuringiensis for potential biotechnological applications,” (Plácido et al., 2016 [2].

  12. Peptide isolated from Cry1Ab16 toxin present in Bacillus thuringiensis: Synthesis and morphology data for layer-by-layer films studied by atomic force microscopy.

    Science.gov (United States)

    Plácido, Alexandra; de Oliveira Farias, Emanuel Airton; Marani, Mariela M; Gomes Vasconcelos, Andreanne; Leite, José R S A; Delerue-Matos, Cristina

    2016-09-01

    The peptide PcL342-354C was obtained from the Cry1Ab16 toxin present in Bacillus thuringiensis ("Computational Modeling Deduced Three Dimensional Structure of Cry1Ab16 Toxin from B. thuringiensis AC11" (Kashyap, 2012) [1]). In this data article, we report the synthesis and characterization of the PcL342-354C peptide by MALDI-TOF/TOF mass spectrometry. In addition, the preparation of layer-by-layer films is shown based on interspersion of this peptide with both polyethylenimine (PEI) and poly(sodium 4-styrenesulfonate) (PSS), self-assembled on ITO (indium tin oxide) electrodes. The morphology of the ITO/PEI/PSS/PcL342-354C film was analyzed using atomic force microscopy (AFM). We also evaluated the effect of the number of bilayers in ITO/PEI/(PSS/PcL342-354C) n on the morphology of the film using AFM amplitude images. Further details about this study were published elsewhere, "Layer-by-layer films containing peptides of the Cry1Ab16 toxin from B. thuringiensis for potential biotechnological applications," (Plácido et al., 2016) [2].

  13. Layer-by-Layer modification of poly (methyl methacrylate) intra ocular lens: drug delivery applications.

    Science.gov (United States)

    Manju, S; Kunnatheeri, Sreenivasan

    2010-01-01

    Even though infection followed by Intra ocular lens (IOL) implantation is a rare complication, therapeutic options are limited and it affects the vision seriously. Interestingly, IOL itself acts as substrate for the adhesion and proliferation of bacteria. An approach to facilitate antibacterial drug adsorption onto the surface of IOL through the modification of IOL surface using the concept of Layer-by-Layer (LbL) formation without sacrificing the vital optical features of the IOLs is presented here. Polyelectroylte multilayers incorporating ampicillin was fabricated on the IOLs using LbL deposition of Poly (sodium 4-styrenesulfonate) (PSS) and Poly (ethylenimine) (PEI). Altogether six layers were formed. The layer formation enabled the IOL to adsorb the drug and modulated the release in a sustained fashion. It appears that using this strategy, IOLs could be modified using a variety of degradable or non-degradable materials to precisely control the delivery of active components to protect eye and the device.

  14. Experimental Study of Natural Gas Storage in Hydrates

    Institute of Scientific and Technical Information of China (English)

    孙志高; 王如竹; 郭开华; 樊栓狮

    2004-01-01

    Hydrate formation rate plays an important role in the making of hydrates for natural gas storage. The effect of sodium dodecyl sulfate (SDS), alkyl polysaccharide glycoside (APG) and cyclopentane (CP) on natural gas hydrate formation rate, induction time and storage capacity was studied. Micellar surfactant solutions were found to increase hydrate formation rate in a quiescent system and improve hydrate formation rate and natural gas storage capacity. The process of hydrate formation includes two stages with surfactant presence. Hydrate forms quickly in the first stage, and then the formation rate is slowed down. Surfactants (SDS or APG) reduce the induction time of hydrate formation. The effect of an anionic surfactant (SDS) on gas storage in hydrates is more pronounced compared to a nonionic surfactant (APG). CP also reduces the induction time of hydrate formation, but can not improve the natural gas storage capacity in hydrates.

  15. THCM Coupled Model for Hydrate-Bearing Sediments: Data Analysis and Design of New Field Experiments (Marine and Permafrost Settings)

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, Marcelo J. [Texas A & M Univ., College Station, TX (United States); Santamarina, J. Carlos [King Abdullah Univ. of Science and Technology (Saudi Arabia)

    2017-02-14

    Gas hydrates are solid compounds made of water molecules clustered around low molecular weight gas molecules such as methane, hydrogen, and carbon dioxide. Methane hydrates form under pressure (P) and temperature (T) conditions that are common in sub-permafrost layers and in deep marine sediments. Stability conditions constrain the occurrence of gas hydrates to submarine sediments and permafrost regions. The amount of technically recoverable methane trapped in gas hydrate may exceed 104tcf. Gas hydrates are a potential energy resource, can contribute to climate change, and can cause large-scale seafloor instabilities. In addition, hydrate formation can be used for CO2 sequestration (also through CO2-CH4 replacement), and efficient geological storage seals. The experimental study of hydrate bearing sediments has been hindered by the very low solubility of methane in water (lab testing), and inherent sampling difficulties associated with depressurization and thermal changes during core extraction. This situation has prompted more decisive developments in numerical modeling in order to advance the current understanding of hydrate bearing sediments, and to investigate/optimize production strategies and implications. The goals of this research has been to addresses the complex thermo-hydro-chemo-mechanical THCM coupled phenomena in hydrate-bearing sediments, using a truly coupled numerical model that incorporates sound and proven constitutive relations, satisfies fundamental conservation principles. Analytical solutions aimed at verifying the proposed code have been proposed as well. These tools will allow to better analyze available data and to further enhance the current understanding of hydrate bearing sediments in view of future field experiments and the development of production technology.

  16. Methane Recovery from Hydrate-bearing Sediments

    Energy Technology Data Exchange (ETDEWEB)

    J. Carlos Santamarina; Costas Tsouris

    2011-04-30

    Gas hydrates are crystalline compounds made of gas and water molecules. Methane hydrates are found in marine sediments and permafrost regions; extensive amounts of methane are trapped in the form of hydrates. Methane hydrate can be an energy resource, contribute to global warming, or cause seafloor instability. This study placed emphasis on gas recovery from hydrate bearing sediments and related phenomena. The unique behavior of hydrate-bearing sediments required the development of special research tools, including new numerical algorithms (tube- and pore-network models) and experimental devices (high pressure chambers and micromodels). Therefore, the research methodology combined experimental studies, particle-scale numerical simulations, and macro-scale analyses of coupled processes. Research conducted as part of this project started with hydrate formation in sediment pores and extended to production methods and emergent phenomena. In particular, the scope of the work addressed: (1) hydrate formation and growth in pores, the assessment of formation rate, tensile/adhesive strength and their impact on sediment-scale properties, including volume change during hydrate formation and dissociation; (2) the effect of physical properties such as gas solubility, salinity, pore size, and mixed gas conditions on hydrate formation and dissociation, and it implications such as oscillatory transient hydrate formation, dissolution within the hydrate stability field, initial hydrate lens formation, and phase boundary changes in real field situations; (3) fluid conductivity in relation to pore size distribution and spatial correlation and the emergence of phenomena such as flow focusing; (4) mixed fluid flow, with special emphasis on differences between invading gas and nucleating gas, implications on relative gas conductivity for reservoir simulations, and gas recovery efficiency; (5) identification of advantages and limitations in different gas production strategies with

  17. Gas Hydrate Storage of Natural Gas

    Energy Technology Data Exchange (ETDEWEB)

    Rudy Rogers; John Etheridge

    2006-03-31

    Environmental and economic benefits could accrue from a safe, above-ground, natural-gas storage process allowing electric power plants to utilize natural gas for peak load demands; numerous other applications of a gas storage process exist. A laboratory study conducted in 1999 to determine the feasibility of a gas-hydrates storage process looked promising. The subsequent scale-up of the process was designed to preserve important features of the laboratory apparatus: (1) symmetry of hydrate accumulation, (2) favorable surface area to volume ratio, (3) heat exchanger surfaces serving as hydrate adsorption surfaces, (4) refrigeration system to remove heat liberated from bulk hydrate formation, (5) rapid hydrate formation in a non-stirred system, (6) hydrate self-packing, and (7) heat-exchanger/adsorption plates serving dual purposes to add or extract energy for hydrate formation or decomposition. The hydrate formation/storage/decomposition Proof-of-Concept (POC) pressure vessel and supporting equipment were designed, constructed, and tested. This final report details the design of the scaled POC gas-hydrate storage process, some comments on its fabrication and installation, checkout of the equipment, procedures for conducting the experimental tests, and the test results. The design, construction, and installation of the equipment were on budget target, as was the tests that were subsequently conducted. The budget proposed was met. The primary goal of storing 5000-scf of natural gas in the gas hydrates was exceeded in the final test, as 5289-scf of gas storage was achieved in 54.33 hours. After this 54.33-hour period, as pressure in the formation vessel declined, additional gas went into the hydrates until equilibrium pressure/temperature was reached, so that ultimately more than the 5289-scf storage was achieved. The time required to store the 5000-scf (48.1 hours of operating time) was longer than designed. The lower gas hydrate formation rate is attributed to a

  18. Mass fractionation of noble gases in synthetic methane hydrate: Implications for naturally occurring gas hydrate dissociation

    Science.gov (United States)

    Hunt, Andrew G.; Stern, Laura; Pohlman, John W.; Ruppel, Carolyn; Moscati, Richard J.; Landis, Gary P.

    2013-01-01

    As a consequence of contemporary or longer term (since 15 ka) climate warming, gas hydrates in some settings may presently be dissociating and releasing methane and other gases to the ocean-atmosphere system. A key challenge in assessing the impact of dissociating gas hydrates on global atmospheric methane is the lack of a technique able to distinguish between methane recently released from gas hydrates and methane emitted from leaky thermogenic reservoirs, shallow sediments (some newly thawed), coal beds, and other sources. Carbon and deuterium stable isotopic fractionation during methane formation provides a first-order constraint on the processes (microbial or thermogenic) of methane generation. However, because gas hydrate formation and dissociation do not cause significant isotopic fractionation, a stable isotope-based hydrate-source determination is not possible. Here, we investigate patterns of mass-dependent noble gas fractionation within the gas hydrate lattice to fingerprint methane released from gas hydrates. Starting with synthetic gas hydrate formed under laboratory conditions, we document complex noble gas fractionation patterns in the gases liberated during dissociation and explore the effects of aging and storage (e.g., in liquid nitrogen), as well as sampling and preservation procedures. The laboratory results confirm a unique noble gas fractionation pattern for gas hydrates, one that shows promise in evaluating modern natural gas seeps for a signature associated with gas hydrate dissociation.

  19. Hydration Properties of Ground Granulated Blast-Furnace Slag (GGBS Under Different Hydration Environments

    Directory of Open Access Journals (Sweden)

    Shuhua LIU

    2017-02-01

    Full Text Available The hydration properties of various cementitious materials containing Ground Granulated Blast-furnace Slag (GGBS, two alkali-activated slag cements (AAS-1 and AAS-2 in which sodium silicate and sodium hydroxide act as alkaline activators respectively, supersulfated cement (SSC and slag Portland cement(PSC, are compared with ordinary Portland cement (OPC to investigate the effect of activating environment on the hydration properties in this study by determining the compressive strength of the pastes, the hydration heat of binders within 96 hours, and the hydration products at age of 28 days. The results show that C-S-H gels are the main hydrated products for all cementitious systems containing GGBS. Ca(OH2 is the hydration products of OPC and PSC paste. However, ettringite and gypsum crystals instead of Ca(OH2 are detected in SSC paste. Additionally, tobermorite, a crystalline C-S-H, and calcite are hydrated products in AAS-1. Tobermorite, cowlesite and calcite are hydrated products of AAS-2 as well. Based on strength results, AAS-1 paste exhibits the highest compressive strength followed by POC, PSC, SSC in order at all testing ages and AAS-2 give the lowest compressive strength except for the early age at 3 days, which is higher than SSC but still lower than PSC. From hydration heat analysis, alkalinity in the reaction solution is a vital factor influencing the initial hydration rate and the initial hydration rate from higher to lower is AAS-2, AAS-1, OPC, PSC and SSC. Although AAS possesses a faster reaction rate in the initial hours, cumulative hydration heat of AAS is comparably lower than that of OPC, but higher than those of PSC and SSC in turn, which indicates that the hydration heat of clinkers is much higher than that of slag.DOI: http://dx.doi.org/10.5755/j01.ms.23.1.14934

  20. Detection and Production of Methane Hydrate

    Energy Technology Data Exchange (ETDEWEB)

    George Hirasaki; Walter Chapman; Gerald Dickens; Colin Zelt; Brandon Dugan; Kishore Mohanty; Priyank Jaiswal

    2011-12-31

    This project seeks to understand regional differences in gas hydrate systems from the perspective of as an energy resource, geohazard, and long-term climate influence. Specifically, the effort will: (1) collect data and conceptual models that targets causes of gas hydrate variance, (2) construct numerical models that explain and predict regional-scale gas hydrate differences in 2-dimensions with minimal 'free parameters', (3) simulate hydrocarbon production from various gas hydrate systems to establish promising resource characteristics, (4) perturb different gas hydrate systems to assess potential impacts of hot fluids on seafloor stability and well stability, and (5) develop geophysical approaches that enable remote quantification of gas hydrate heterogeneities so that they can be characterized with minimal costly drilling. Our integrated program takes advantage of the fact that we have a close working team comprised of experts in distinct disciplines. The expected outcomes of this project are improved exploration and production technology for production of natural gas from methane hydrates and improved safety through understanding of seafloor and well bore stability in the presence of hydrates. The scope of this project was to more fully characterize, understand, and appreciate fundamental differences in the amount and distribution of gas hydrate and how this would affect the production potential of a hydrate accumulation in the marine environment. The effort combines existing information from locations in the ocean that are dominated by low permeability sediments with small amounts of high permeability sediments, one permafrost location where extensive hydrates exist in reservoir quality rocks and other locations deemed by mutual agreement of DOE and Rice to be appropriate. The initial ocean locations were Blake Ridge, Hydrate Ridge, Peru Margin and GOM. The permafrost location was Mallik. Although the ultimate goal of the project was to understand

  1. Prospecting for marine gas hydrate resources

    Science.gov (United States)

    Boswell, Ray; Shipp, Craig; Reichel, Thomas; Shelander, Dianna; Saeki, Tetsuo; Frye, Matthew; Shedd, William; Collett, Timothy S.; McConnell, Daniel R.

    2016-01-01

    As gas hydrate energy assessment matures worldwide, emphasis has evolved away from confirmation of the mere presence of gas hydrate to the more complex issue of prospecting for those specific accumulations that are viable resource targets. Gas hydrate exploration now integrates the unique pressure and temperature preconditions for gas hydrate occurrence with those concepts and practices that are the basis for conventional oil and gas exploration. We have aimed to assimilate the lessons learned to date in global gas hydrate exploration to outline a generalized prospecting approach as follows: (1) use existing well and geophysical data to delineate the gas hydrate stability zone (GHSZ), (2) identify and evaluate potential direct indications of hydrate occurrence through evaluation of interval of elevated acoustic velocity and/or seismic events of prospective amplitude and polarity, (3) mitigate geologic risk via regional seismic and stratigraphic facies analysis as well as seismic mapping of amplitude distribution along prospective horizons, and (4) mitigate further prospect risk through assessment of the evidence of gas presence and migration into the GHSZ. Although a wide range of occurrence types might ultimately become viable energy supply options, this approach, which has been tested in only a small number of locations worldwide, has directed prospect evaluation toward those sand-hosted, high-saturation occurrences that were presently considered to have the greatest future commercial potential.

  2. Gas Hydrates Research Programs: An International Review

    Energy Technology Data Exchange (ETDEWEB)

    Jorge Gabitto; Maria Barrufet

    2009-12-09

    Gas hydrates sediments have the potential of providing a huge amount of natural gas for human use. Hydrate sediments have been found in many different regions where the required temperature and pressure conditions have been satisfied. Resource exploitation is related to the safe dissociation of the gas hydrate sediments. Basic depressurization techniques and thermal stimulation processes have been tried in pilot efforts to exploit the resource. There is a growing interest in gas hydrates all over the world due to the inevitable decline of oil and gas reserves. Many different countries are interested in this valuable resource. Unsurprisingly, developed countries with limited energy resources have taken the lead in worldwide gas hydrates research and exploration. The goal of this research project is to collect information in order to record and evaluate the relative strengths and goals of the different gas hydrates programs throughout the world. A thorough literature search about gas hydrates research activities has been conducted. The main participants in the research effort have been identified and summaries of their past and present activities reported. An evaluation section discussing present and future research activities has also been included.

  3. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Buddy King

    2004-03-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is in the second year of a three-year endeavor being sponsored by Maurer Technology, Noble, and Anadarko Petroleum, in partnership with the DOE. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition. We plan to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. We also plan to design and implement a program to safely and economically drill, core and produce gas from arctic hydrates. The current work scope is to drill and core a well on Anadarko leases in FY 2003 and 2004. We are also using an on-site core analysis laboratory to determine some of the physical characteristics of the hydrates and surrounding rock. The well is being drilled from a new Anadarko Arctic Platform that will have minimal footprint and environmental impact. We hope to correlate geology, geophysics, logs, and drilling and production data to allow reservoir models to be calibrated. Ultimately, our goal is to form an objective technical and economic evaluation of reservoir potential in Alaska.

  4. Methane hydrate stability and anthropogenic climate change

    Directory of Open Access Journals (Sweden)

    D. Archer

    2007-07-01

    Full Text Available Methane frozen into hydrate makes up a large reservoir of potentially volatile carbon below the sea floor and associated with permafrost soils. This reservoir intuitively seems precarious, because hydrate ice floats in water, and melts at Earth surface conditions. The hydrate reservoir is so large that if 10% of the methane were released to the atmosphere within a few years, it would have an impact on the Earth's radiation budget equivalent to a factor of 10 increase in atmospheric CO2.

    Hydrates are releasing methane to the atmosphere today in response to anthropogenic warming, for example along the Arctic coastline of Siberia. However most of the hydrates are located at depths in soils and ocean sediments where anthropogenic warming and any possible methane release will take place over time scales of millennia. Individual catastrophic releases like landslides and pockmark explosions are too small to reach a sizable fraction of the hydrates. The carbon isotopic excursion at the end of the Paleocene has been interpreted as the release of thousands of Gton C, possibly from hydrates, but the time scale of the release appears to have been thousands of years, chronic rather than catastrophic.

    The potential climate impact in the coming century from hydrate methane release is speculative but could be comparable to climate feedbacks from the terrestrial biosphere and from peat, significant but not catastrophic. On geologic timescales, it is conceivable that hydrates could release as much carbon to the atmosphere/ocean system as we do by fossil fuel combustion.

  5. Methane hydrate stability and anthropogenic climate change

    Directory of Open Access Journals (Sweden)

    D. Archer

    2007-04-01

    Full Text Available Methane frozen into hydrate makes up a large reservoir of potentially volatile carbon below the sea floor and associated with permafrost soils. This reservoir intuitively seems precarious, because hydrate ice floats in water, and melts at Earth surface conditions. The hydrate reservoir is so large that if 10% of the methane were released to the atmosphere within a few years, it would have an impact on the Earth's radiation budget equivalent to a factor of 10 increase in atmospheric CO2.

    Hydrates are releasing methane to the atmosphere today in response to anthropogenic warming, for example along the Arctic coastline of Siberia. However most of the hydrates are located at depths in soils and ocean sediments where anthropogenic warming and any possible methane release will take place over time scales of millennia. Individual catastrophic releases like landslides and pockmark explosions are too small to reach a sizable fraction of the hydrates. The carbon isotopic excursion at the end of the Paleocene has been interpreted as the release of thousands of Gton C, possibly from hydrates, but the time scale of the release appears to have been thousands of years, chronic rather than catastrophic.

    The potential climate impact in the coming century from hydrate methane release is speculative but could be comparable to climate feedbacks from the terrestrial biosphere and from peat, significant but not catastrophic. On geologic timescales, it is conceivable that hydrates could release much carbon to the atmosphere/ocean system as we do by fossil fuel combustion.

  6. Proton percolation on hydrated lysozyme powders

    OpenAIRE

    Careri, G; Giansanti, A; Rupley, John A.

    1986-01-01

    The framework of percolation theory is used to analyze the hydration dependence of the capacitance measured for protein samples of pH 3-10, at frequencies from 10 kHz to 4 MHz. For all samples there is a critical value of the hydration at which the capacitance sharply increases with increase in hydration level. The threshold hc = 0.15 g of water per g of protein is independent of pH below pH 9 and shows no solvent deuterium isotope effect. The fractional coverage of the surface at hc is in cl...

  7. Glass powder blended cement hydration modelling

    Science.gov (United States)

    Saeed, Huda

    The use of waste materials in construction is among the most attractive options to consume these materials without affecting the environment. Glass is among these types of potential waste materials. In this research, waste glass in powder form, i.e. glass powder (GP) is examined for potential use in enhancing the characteristics of concrete on the basis that it is a pozzolanic material. The experimental and the theoretical components of the work are carried out primarily to prove that glass powder belongs to the "family" of the pozzolanic materials. The chemical and physical properties of the hydrated activated glass powder and the hydrated glass powder cement on the microstructure level have been studied experimentally and theoretically. The work presented in this thesis consists of two main phases. The first phase contains experimental investigations of the reaction of glass powder with calcium hydroxide (CH) and water. In addition, it includes experiments that are aimed at determining the consumption of water and CH with time. The reactivity, degree of hydration, and nature of the pore solution of the glass powder-blended cement pastes and the effect of adding different ratios of glass powder on cement hydration is also investigated. The experiments proved that glass powder has a pozzolanic effect on cement hydration; hence it enhances the chemical and physical properties of cement paste. Based on the experimental test results, it is recommended to use a glass powder-to-cement ratio (GP/C) of 10% as an optimum ratio to achieve the best hydration and best properties of the paste. Two different chemical formulas for the produced GP C-S-H gel due to the pure GP and GP-CH pozzolanic reaction hydration are proposed. For the pure GP hydration, the produced GP C-S-H gel has a calcium-to-silica ratio (C/S) of 0.164, water-to-silica ratio (H/S) of 1.3 and sodium/silica ratio (N/S) of 0.18. However, for the GP-CH hydration, the produced GP C-S-H gel has a C/S ratio of 1

  8. Modeling of stability of gas hydrates under permafrost in an environment of surface climatic change – terrestrial case, Beaufort-Mackenzie basin, Canada

    Directory of Open Access Journals (Sweden)

    J. Majorowicz

    2011-09-01

    Full Text Available Modeling of the onset of permafrost formation and succeeding gas hydrate formation in the changing surface temperature environment has been done for the Beaufort-Mackenzie Basin (BMB. Numerical 1-D modeling is constrained by deep heat flow from deep well bottom hole temperatures, deep conductivity, present permafrost thickness and thickness of Type I gas hydrates. Latent heat effects were applied to the model for the entire ice bearing permafrost and Type I hydrate intervals. Modeling for a set of surface temperature forcing during the glacial-interglacial history including the last 14 Myr was performed. Two scenarios of gas formation were considered; case 1: formation of gas hydrate from gas entrapped under deep geological seals and case 2: formation of gas hydrate from gas in a free pore space simultaneously with permafrost formation. In case 1, gas hydrates could have formed at a depth of about 0.9 km only some 1 Myr ago. In case 2, the first gas hydrate formed in the depth range of 290–300 m shortly after 6 Myr ago when the GST dropped from −4.5 °C to −5.5. °C. The gas hydrate layer started to expand both downward and upward subsequently. These models show that the gas hydrate zone, while thinning persists under the thick body of BMB permafrost through the current interglacial warming periods.

  9. Effect of Some Admixtures on the Hydration of Silica Fume and Hydrated Lime

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The effects of sodium salt of naphthalene formaldehyde sulfonic acid and stearic acid on the hydration of silica fume and Ca(0H)2 have been investigated. The hydration was carried out at 60℃ and W/S ratio of 4 for various time intervals namely, 1, 3, 7 and 28 days and in the presence of 0.2% and 5% superplasticizer and stearic acid. The results of the hydration kinetics show that both admixtures accelerate the hydration reaction of silica fume and calcium hydroxide during the first 7 days. Whereas, after 28 days hydration there is no significant effect. Generally, most of free calcium hydroxide seems to be consumed after 28 days. In addition, the phase composition as well as the microstructure of the formed hydrates was examined by using X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM) respectively.

  10. Polylysine-modified polyethylenimine (PEI-PLL) mediated VEGF gene delivery protects dopaminergic neurons in cell culture and in rat models of Parkinson's Disease (PD).

    Science.gov (United States)

    Sheikh, Muhammad Abid; Malik, Yousra Saeed; Xing, Zhenkai; Guo, Zhaopei; Tian, Huayu; Zhu, Xiaojuan; Chen, Xuesi

    2017-05-01

    Parkinson's Disease (PD) is a chronic neurodegenerative disorder characterized by motor deficits which result from the progressive loss of dopaminergic neurons. Gene therapy using growth factors such as VEGF seems to be a viable approach for potential therapeutic treatment of PD. In this study, we utilized a novel non-viral gene carrier designated as PEI-PLL synthesized by our laboratory to deliver VEGF gene to study its effect by using both cell culture as well as animal models of PD. For cell culture experiments, we utilized 6-hydroxydopamine (6-OHDA) mediated cell death model of MN9D cells following transfection with either a control plasmid or VEGF expressing plasmid. As compared to control transfected cells, PEI-PLL mediated VEGF gene delivery to MN9D cells resulted in increased cell viability, increase in the number of Tyrosine hydroxylase (TH) positive cells and decreased apoptosis following 6-OHDA insult. Next, we studied the therapeutic potential of PEI-PLL mediated VEGF gene delivery in SNPc by using unilateral 6-OHDA Medial forebrain bundle (MFB) lesion model of PD in rats. VEGF administration prevented the loss of motor functions induced by 6-OHDA as determined by behavior analysis. Similarly, VEGF inhibited the 6-OHDA mediated loss of DA neurons in Substantia Nigra Pars Compacta (SNPc) as well as DA nerve fibers in striatum as determined by TH immunostaining. In addition, PEI-PLL mediated VEGF gene delivery also prevented apoptosis and microglial activation in PD rat models. Together, these results clearly demonstrated the beneficial effects of PEI-PLL mediated VEGF gene delivery on dopaminergic system in both cell culture and animal models of PD. In this report, we exploited the potential of PEI-PLL to deliver VEGF gene for the potential therapeutic treatment of PD by using both cell culture and animal models of PD. To the best of our knowledge, this is the first report describing the use of novel polymeric gene carriers for the delivery of VEGF gene

  11. Theoretical Investigation on the Adsorption of Ag+ and Hydrated Ag+ Cations on Clean Si(111)Surface

    Institute of Scientific and Technical Information of China (English)

    SHENG Yong-Li; LI Meng-Hua; WANG Zhi-Guo; LIU Yong-Jun

    2008-01-01

    In this paper,the adsorption of Ag+ and hydrated Ag+ cations on clean Si(111)surface were investigated by using cluster(Gaussian 03)and periodic(DMol3)ab initio calculations.Si(111)surface was described with cluster models(Si14H17 and Si22H21)and a four-silicon layer slab with periodic boundary conditions.The effect of basis set superposition error(BSSE)was taken into account by applying the counterpoise correction.The calculated results indicated that the binding energies between hydrated Ag+ cations and clean Si(111)surface are large,suggesting a strong interaction between hydrated Ag+ cations and the semiconductor surface.With the increase of number,water molecules form hydrogen bond network with one another and only one water molecule binds directly to the Ag+ cation.The Ag+ cation in aqueous solution will safely attach to the clean Si(111)surface.

  12. Polyionic complex of single-walled carbon nanotubes and PEG-grafted-hyperbranched polyethyleneimine (PEG-PEI-SWNT) for an improved doxorubicin loading and delivery: development and in vitro characterization.

    Science.gov (United States)

    Farvadi, Fakhrossadat; Tamaddon, AliMohammad; Sobhani, Zahra; Abolmaali, Samira Sadat

    2016-05-13

    To take advantages of single-walled carbon nanotubes (SWNTs) for cellular delivery of chemotherapeutic agents (e.g. doxorubicin) in order to decrease general toxicities of doxorubicin (DOX) and to promote the efficacy, we aimed to develop a novel approach to stabilize SWNTs through consequent steps of oxidation and PEG-g-PEI polyionic complexation (PEG-PEI-SWNT). The DOX loading capacity of modified SWNTs was about 900%. Moreover, it showed an enhanced dispersibility in physiologic-stimulated medium. DOX release was prolonged, independent of dilution, and exhibited an acidic pH-stimulated release. Therefore, PEG-PEI-SWNT could be used for cancer chemotherapy in vivo.

  13. Three-dimensional distribution of gas hydrate beneath southern Hydrate Ridge: Constraints from ODP Leg 204

    Science.gov (United States)

    Trehu, A.M.; Long, P.E.; Torres, M.E.; Bohrmann, G.; Rack, F.R.; Collett, T.S.; Goldberg, D.S.; Milkov, A.V.; Riedel, M.; Schultheiss, P.; Bangs, N.L.; Barr, S.R.; Borowski, W.S.; Claypool, G.E.; Delwiche, M.E.; Dickens, G.R.; Gracia, E.; Guerin, G.; Holland, M.; Johnson, J.E.; Lee, Y.-J.; Liu, C.-S.; Su, X.; Teichert, B.; Tomaru, H.; Vanneste, M.; Watanabe, M. E.; Weinberger, J.L.

    2004-01-01

    Large uncertainties about the energy resource potential and role in global climate change of gas hydrates result from uncertainty about how much hydrate is contained in marine sediments. During Leg 204 of the Ocean Drilling Program (ODP) to the accretionary complex of the Cascadia subduction zone, we sampled the gas hydrate stability zone (GHSZ) from the seafloor to its base in contrasting geological settings defined by a 3D seismic survey. By integrating results from different methods, including several new techniques developed for Leg 204, we overcome the problem of spatial under-sampling inherent in robust methods traditionally used for estimating the hydrate content of cores and obtain a high-resolution, quantitative estimate of the total amount and spatial variability of gas hydrate in this structural system. We conclude that high gas hydrate content (30-40% of pore space or 20-26% of total volume) is restricted to the upper tens of meters below the seafloor near the summit of the structure, where vigorous fluid venting occurs. Elsewhere, the average gas hydrate content of the sediments in the gas hydrate stability zone is generally <2% of the pore space, although this estimate may increase by a factor of 2 when patchy zones of locally higher gas hydrate content are included in the calculation. These patchy zones are structurally and stratigraphically controlled, contain up to 20% hydrate in the pore space when averaged over zones ???10 m thick, and may occur in up to ???20% of the region imaged by 3D seismic data. This heterogeneous gas hydrate distribution is an important constraint on models of gas hydrate formation in marine sediments and the response of the sediments to tectonic and environmental change. ?? 2004 Published by Elsevier B.V.

  14. Experimental Investigation of Effect on Hydrate Formation in Spray Reactor

    Directory of Open Access Journals (Sweden)

    Jianzhong Zhao

    2015-01-01

    Full Text Available The effects of reaction condition on hydrate formation were conducted in spray reactor. The temperature, pressure, and gas volume of reaction on hydrate formation were measured in pure water and SDS solutions at different temperature and pressure with a high-pressure experimental rig for hydrate formation. The experimental data and result reveal that additives could improve the hydrate formation rate and gas storage capacity. Temperature and pressure can restrict the hydrate formation. Lower temperature and higher pressure can promote hydrate formation, but they can increase production cost. So these factors should be considered synthetically. The investigation will promote the advance of gas storage technology in hydrates.

  15. A Hydrate Database: Vital to the Technical Community

    Directory of Open Access Journals (Sweden)

    D Sloan

    2007-06-01

    Full Text Available Natural gas hydrates may contain more energy than all the combined other fossil fuels, causing hydrates to be a potentially vital aspect of both energy and climate change. This article is an overview of the motivation, history, and future of hydrate data management using a CODATA vehicle to connect international hydrate databases. The basis is an introduction to the Gas Hydrate Markup Language (GHML to connect various hydrate databases. The accompanying four articles on laboratory hydrate data by Smith et al., on field hydrate data by L?wner et al., on hydrate modeling by Wang et al., and on construction of a Chinese gas hydrate system by Xiao et al. provide details of GHML in their respective areas.

  16. Lithological control on gas hydrate saturation as revealed by signal classification of NMR logging data

    Science.gov (United States)

    Bauer, Klaus; Kulenkampff, Johannes; Henninges, Jan; Spangenberg, Erik

    2015-09-01

    In this paper, nuclear magnetic resonance (NMR) downhole logging data are analyzed with a new strategy to study gas hydrate-bearing sediments in the Mackenzie Delta (NW Canada). In NMR logging, transverse relaxation time (T2) distribution curves are usually used to determine single-valued parameters such as apparent total porosity or hydrocarbon saturation. Our approach analyzes the entire T2 distribution curves as quasi-continuous signals to characterize the rock formation. We apply self-organizing maps, a neural network clustering technique, to subdivide the data set of NMR curves into classes with a similar and distinctive signal shape. The method includes (1) preparation of data vectors, (2) unsupervised learning, (3) cluster definition, and (4) classification and depth mapping of all NMR signals. Each signal class thus represents a specific pore size distribution which can be interpreted in terms of distinct lithologies and reservoir types. A key step in the interpretation strategy is to reconcile the NMR classes with other log data not considered in the clustering analysis, such as gamma ray, hydrate saturation, and other logs. Our results defined six main lithologies within the target zone. Gas hydrate layers were recognized by their low signal amplitudes for all relaxation times. Most importantly, two subtypes of hydrate-bearing shaly sands were identified. They show distinct NMR signals and differ in hydrate saturation and gamma ray values. An inverse linear relationship between hydrate saturation and clay content was concluded. Finally, we infer that the gas hydrate is not grain coating, but rather, pore filling with matrix support is the preferred growth habit model for the studied formation.

  17. Vibrational dynamics of hydration water in amylose

    CERN Document Server

    Cavatorta, F; Albanese, G; Angelini, N

    2002-01-01

    We present a study of the dynamical properties of hydration water associated with amylose helices, based on low-temperature vibrational spectra collected using the TOSCA inelastic spectrometer at ISIS. The structural constraints of the polysaccharidic chains favour the formation of a high-density structure for water, which has been suggested by Imberty and Perez on the basis of conformational analysis. According to this model, hydration water can only enter the pores formed by six adjacent helices and completely fills the pores at a hydration level of about 0.27-g water/g dry amylose. Our measurements show that the dynamical behaviour of hydration water is similar to that observed in high-density amorphous ice. (orig.)

  18. ConocoPhillips Gas Hydrate Production Test

    Energy Technology Data Exchange (ETDEWEB)

    Schoderbek, David; Farrell, Helen; Howard, James; Raterman, Kevin; Silpngarmlert, Suntichai; Martin, Kenneth; Smith, Bruce; Klein, Perry

    2013-06-30

    Work began on the ConocoPhillips Gas Hydrates Production Test (DOE award number DE-NT0006553) on October 1, 2008. This final report summarizes the entire project from January 1, 2011 to June 30, 2013.

  19. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Donn McGuire; Thomas Williams; Bjorn Paulsson; Alexander Goertz

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a drilling hazard by the oil and gas industry for years. Drilling engineers working in Russia, Canada and the USA have documented numerous problems, including drilling kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrates as a potential energy source agree that the resource potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained from physical samples taken from actual hydrate-bearing rocks. This gas-hydrate project is a cost-shared partnership between Maurer Technology, Anadarko Petroleum, Noble Corporation, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The project team drilled and continuously cored the Hot Ice No. 1 well on Anadarko-leased acreage beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and used for determining physical characteristics of hydrates and surrounding rock. After the well was logged, a 3D vertical seismic profile (VSP) was recorded to calibrate the shallow geologic section with seismic data and to investigate techniques to better resolve lateral subsurface variations of potential hydrate-bearing strata. Paulsson Geophysical Services, Inc. deployed their 80 level 3C clamped borehole seismic receiver array in the wellbore to record samples every 25 ft. Seismic vibrators were successively positioned at 1185 different surface positions in a circular pattern around the wellbore. This technique generated a 3D image of the subsurface. Correlations were

  20. Formulating formation mechanism of natural gas hydrates.

    Science.gov (United States)

    Palodkar, Avinash V; Jana, Amiya K

    2017-07-25

    A large amount of energy, perhaps twice the total amount of all other hydrocarbon reserves combined, is trapped within gas hydrate deposits. Despite emerging as a potential energy source for the world over the next several hundred years and one of the key factors in causing future climate change, gas hydrate is poorly known in terms of its formation mechanism. To address this issue, a mathematical formulation is proposed in the form of a model to represent the physical insight into the process of hydrate growth that occurs on the surface and in the irregular nanometer-sized pores of the distributed porous particles. To evaluate the versatility of this rigorous model, the experimental data is used for methane (CH4) and carbon dioxide (CO2) hydrates grown in different porous media with a wide range of considerations.

  1. Hydrate Control for Gas Storage Operations

    Energy Technology Data Exchange (ETDEWEB)

    Jeffrey Savidge

    2008-10-31

    The overall objective of this project was to identify low cost hydrate control options to help mitigate and solve hydrate problems that occur in moderate and high pressure natural gas storage field operations. The study includes data on a number of flow configurations, fluids and control options that are common in natural gas storage field flow lines. The final phase of this work brings together data and experience from the hydrate flow test facility and multiple field and operator sources. It includes a compilation of basic information on operating conditions as well as candidate field separation options. Lastly the work is integrated with the work with the initial work to provide a comprehensive view of gas storage field hydrate control for field operations and storage field personnel.

  2. Quantifying hydrate formation and kinetic inhibition

    Energy Technology Data Exchange (ETDEWEB)

    Sloan, E.D.; Subramanian, S.; Matthews, P.N.; Lederhos, J.P.; Khokhar, A.A. [Colorado School of Mines, Golden, CO (United States). Center for Hydrate Research

    1998-08-01

    In the Prausnitz tradition, molecular and macroscopic evidence of hydrate formation and kinetic inhibition is presented. On the microscopic level, the first Raman spectra are presented for the formation of both uninhibited and inhibited methane hydrates with time. This method has the potential to provide a microscopic-based kinetics model. Three macroscopic aspects of natural gas hydrate kinetic inhibition are also reported: (1) The effect of hydrate dissociation residual structures was measured, which has application in decreasing the time required for subsequent formation. (2) The performance of a kinetic inhibitor (poly(N-vinylcaprolactam) or PVCap) was measured and correlated as a function of PVCap molecular weight and concentrations of PVCap, methanol, and salt in the aqueous phase. (3) Long-duration test results indicated that the use of PVCap can prevent pipeline blockage for a time exceeding the aqueous phase residence time in some gas pipelines.

  3. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Ali Kadaster; Bill Liddell; Tommy Thompson; Thomas Williams; Michael Niedermayr

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project was a cost-shared partnership between Maurer Technology, Noble Corporation, Anadarko Petroleum, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. The work scope included drilling and coring a well (Hot Ice No. 1) on Anadarko leases beginning in FY 2003 and completed in 2004. During the first drilling season, operations were conducted at the site between January 28, 2003 to April 30, 2003. The well was spudded and drilled to a depth of 1403 ft. Due to the onset of warmer weather, work was then suspended for the season. Operations at the site were continued after the tundra was re-opened the following season. Between January 12, 2004 and March 19, 2004, the well was drilled and cored to a final depth of 2300 ft. An on-site core analysis laboratory was built and implemented for determining physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. Final efforts of the project are to correlate geology, geophysics, logs, and drilling and

  4. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Bill Liddell

    2004-11-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is a cost-shared partnership between Maurer Technology, Anadarko Petroleum, Noble Corporation, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to help identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. As part of the project work scope, team members drilled and cored a well (the Hot Ice No. 1) on Anadarko leases beginning in January 2003 and completed in March 2004. Due to scheduling constraints imposed by the Arctic drilling season, operations at the site were suspended between April 21, 2003 and January 30, 2004. An on-site core analysis laboratory was constructed and used for determining physical characteristics of frozen core immediately after it was retrieved from the well. The well was drilled from a new and innovative Anadarko Arctic Platform that has a greatly reduced footprint and environmental impact. Final efforts of the project were to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists for future hydrate operations. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained

  5. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Thomas E. Williams; Keith Millheim; Bill Liddell

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. This gas-hydrate project is a cost-shared partnership between Maurer Technology, Anadarko Petroleum, Noble Corporation, and the U.S. Department of Energy's Methane Hydrate R&D program. The purpose of the project is to build on previous and ongoing R&D in the area of onshore hydrate deposition to help identify, quantify and predict production potential for hydrates located on the North Slope of Alaska. As part of the project work scope, team members drilled and cored a well (the Hot Ice No. 1) on Anadarko leases beginning in January 2003 and completed in March 2004. Due to scheduling constraints imposed by the Arctic drilling season, operations at the site were suspended between April 21, 2003 and January 30, 2004. An on-site core analysis laboratory was constructed and used for determining physical characteristics of frozen core immediately after it was retrieved from the well. The well was drilled from a new and innovative Anadarko Arctic Platform that has a greatly reduced footprint and environmental impact. Final efforts of the project were to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists for future hydrate operations. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained

  6. Experimental Dissociation of Methane Hydrates Through Depressurization

    Science.gov (United States)

    Borgfeldt, T.; Flemings, P. B.; Meyer, D.; You, K.

    2015-12-01

    We dissociated methane hydrates by stepwise depressurization. The initial hydrates were formed by injecting gas into a cylindrical sample of brine-saturated, coarse-grained sand at hydrate-stable conditions with the intention of reaching three-phase equilibrium. The sample was initially at 1°C with a pore pressure of 1775 psi and a salinity of 7 wt. % NaBr. The depressurization setup consisted of one pump filled with tap water attached to the confining fluid port and a second pump attached to the inlet port where the methane was injected. Depressurization was conducted over sixteen hours at a constant temperature of 1°C. The pore pressure was stepwise reduced from 1775 psi to atmospheric pressure by pulling known volumes of gas from the sample. After each extraction, we recorded the instantaneous and equilibrium pore pressure. 0.503 moles of methane were removed from the sample. The pore pressure decreased smoothly and nonlinearly with the cumulative gas withdrawn from the sample. We interpret that hydrate began to dissociate immediately with depressurization, and it continued to dissociate when the pressure decreased below the three-phase pressure for 1°C and 0 wt. % salinity. Two breaks in slope in the pressure vs. mass extracted data are bounded by smooth, nonlinear curves with differing slopes on either side. We attribute the breaks to dissociation of three zones of hydrate concentration. We created a box model to simulate the experimental behavior. For a 10% initial gas saturation (estimated from the hydrate formation experiment and based on mass conservation), an initial hydrate saturation of 55% is required to match the total methane extracted from the sample. Future experiments will be conducted over a longer timespan while monitoring hydrate dissociation with CT imaging throughout the process.

  7. Hydration of polyethylene glycol-grafted liposomes.

    OpenAIRE

    Tirosh, O; Barenholz, Y.; Katzhendler, J; Priev, A

    1998-01-01

    This study aimed to characterize the effect of polyethylene glycol of 2000 molecular weight (PEG2000) attached to a dialkylphosphatidic acid (dihexadecylphosphatidyl (DHP)-PEG2000) on the hydration and thermodynamic stability of lipid assemblies. Differential scanning calorimetry, densitometry, and ultrasound velocity and absorption measurements were used for thermodynamic and hydrational characterization. Using a differential scanning calorimetry technique we showed that each molecule of PEG...

  8. Preservation of methane hydrate at 1 atm

    Science.gov (United States)

    Stern, L.A.; Circone, S.; Kirby, S.H.; Durham, W.B.

    2001-01-01

    A "pressure-release" method that enables reproducible bulk preservation of pure, porous, methane hydrate at conditions 50 to 75 K above its equilibrium T (193 K) at 1 atm is refined. The amount of hydrate preserved by this method appears to be greatly in excess of that reported in the previous citations, and is likely the result of a mechanism different from ice shielding.

  9. Adsorption of hydrated hydroxide and hydronium ions on Ag(1 1 1). A quantum mechanical investigation

    Science.gov (United States)

    Patrito, E. M.; Paredes-Olivera, P.

    2003-03-01

    In this paper we have studied comparatively the adsorption of hydroxide and hydronium ions, extending our previous study on hydronium adsorption [J. Phys. Chem. B. 105 (2001) 7227] and emphasizing the adsorption of hydroxide. The calculations were performed on the 111 surface of silver using ab initio quantum mechanical methods (Hartree-Fock+Moller-Plesset second order perturbation theory). The adsorption was investigated for the bare and the hydrated ions (up to three water molecules). Binding energies, equilibrium structures and charge transfer processes were investigated. While the successive hydration of hydronium detaches the ion from the surface, the hydrated hydroxide anion remains specifically adsorbed. Charge transfer processes between the adsorbates and the surface were studied using electron density difference plots and effective charges obtained from Mulliken populations and from surface-dipole moment curves. The energetics of the surface reactions leading to the formation of the hydrated hydronium and hydroxide ions from the bare adsorbed ions and water molecules was also investigated. Both reactions are exothermic mainly due to the formation of strong hydrogen bonds. The effect of an external homogeneous electric field perpendicular to the surface on different adsorbate properties was investigated for the bare and hydrated hydroxide ion in order to model the environment of the electrical double layer. The electric field affects the orientation of the water molecules on the surface and the hydroxide surface distance.

  10. Hydration of the cyanide ion: an ab initio quantum mechanical charge field molecular dynamics study.

    Science.gov (United States)

    Moin, Syed Tarique; Hofer, Thomas S

    2014-12-21

    This paper presents an ab initio quantum mechanical charge field molecular dynamics simulation study of the cyanide anion (CN(-)) in aqueous solution where hydrogen bond formation plays a dominant role in the hydration process. Preferential orientation of water hydrogens compared to oxygen atoms was quantified in terms of radial, angular as well as coordination number distributions. All structural results indicate that the water hydrogens are attracted towards CN(-) atoms, thus contributing to the formation of the hydration layer. Moreover, a clear picture of the local arrangement of water molecules around the ellipsoidal CN(-) ion is provided via angular-radial distribution and spatial distribution functions. Apart from the structural analysis, the evaluation of water dynamics in terms of ligand mean residence times and H-bond correlation functions indicates the weak structure making capacity of the CN(-) ion. The similar values of H-bond lifetimes obtained for the NHwat and CHwat bonds indicate an isokinetic behaviour of these H-bonds, since there is a very small difference in the magnitude of the lifetimes. On the other hand, the H-bond lifetimes between water molecules of the hydration shell, and between solute and solvent evidence the slightly stable hydration of the CN(-). Overall, the H-bonding dominates in the hydration process of the cyanide anion enabling it to become soluble in the aqueous environment associated to chemical and biological processes.

  11. Evaluating the mucoadhesive properties of drug delivery systems based on hydrated thiolated alginate.

    Science.gov (United States)

    Davidovich-Pinhas, Maya; Harari, Offer; Bianco-Peled, Havazelet

    2009-05-21

    Mucoadhesive polymers have been proposed as drug delivery carriers due to their ability to adhere to the mucus layer. A relatively new class of mucoadhesive polymers, termed thiomers, was suggested as an improved carrier capable of creating disulfide covalent bond with the mucus. Since the wet physiological environment is likely to cause any delivery system to adsorb water and arrive hydrated to its target, studying the performance of mucoadhesive systems in their hydrated form is of major importance. Model thiomer, alginate-thiol, were synthesized and characterized the product using Nuclear Magnetic Resonance (NMR), Fourier Transform Infra Red spectroscopy (FTIR). The swelling behavior was determined gravimetrically and found to be affected from the thiolation. Interactions between the alginate-thiol and mucin glycoproteins, which are believed to be an outcome of disulfide bonds, were verified using rheology experiments. Adhesion of hydrated tablets with different cross linking densities to porcine's fresh small intestine tissue were characterized using a Lloyd Tensile Machine. It was shown that the thiolation did not improve the adhesion properties of hydrated tablets. It appears that the benefit achieved by adding thiol group to the polymer in dry tablet form was flawed in hydrated form due to formation of inter-molecular disulfide junctions.

  12. O ENVELHECIMENTO, A DOENÇA DE ALZHEIMER E AS CONTRIBUIÇÕES DO PROGRAMA DE ENRIQUECIMENTO INSTRUMENTAL (PEI

    Directory of Open Access Journals (Sweden)

    Antonia Rozeli Roberto de Oliveira

    2010-01-01

    Full Text Available Ese artículo tiene como propuesta presentar el envejecimiento como un proceso individualizado con potencialidades únicas y distintas, haciendo distinción entre la vejez normal y la patológica. Se enfatiza que el envejecimiento exitoso depende en gran parte de la prevención de enfermedades, adecuado condicionamiento físico y preservación de las funciones cognitivas. Sin embargo, estudios epidemiológicos señalan que ancianos con ligeras alteraciones cognitivas presentan un mayor riesgo de desarrollar la Enfermedad de Alzheimer (EA, considerada el diagnóstico más frecuente entre las demencias. Considerándose que esa condición afecta el cerebro, ocasionando perdida de la memoria y el comprometimiento en varias áreas cognitivas (lenguaje, función ejecutiva, praxia, gnosi, etc. son propuestas alternativas de tratamiento más allá de la terapéutica farmacológica caracterizando la rehabilitación neuropsicológica. En ese estudio, en especial, intentase abordar las posibilidades de uso del Programa de Enriquecimiento Instrumental (PEI y de la Experiencia de la Aprendizaje Mediada (EAM en los programas de rehabilitación cognitiva direccionado a la EA, visando favorecer la optimización de las capacidades residuales y disminuir el impacto negativo en la cualidad de vida de estas personas.

  13. Application of PEI-Modified Magnetic Nanoparticles as Gene Transfer Vector for the Genetic Modification of Animals

    Directory of Open Access Journals (Sweden)

    Jinhui Cui

    2012-01-01

    Full Text Available To evaluate the performance of the magnetic nanoparticles as gene transfer vector for breeding transgenic animals, we investigated a new approach to deliver green fluorescent protein (GFP gene to porcine kidney 15 (PK-15 and porcine embryonic fibroblast (PEF cells using PEI-modified magnetic nanoparticles as gene vector. The morphology of the nanoparticles and nanoparticle/DNA complexes was characterized using scanning electron microscopy. It was found that the surface of the particles becomes coarse and rough with increased average diameter, which implied the effective conjugating between nanoparticles with DNA. The zeta potential of nanoparticle/DNA complexes drops down from +29.4 mV to +23.1 mV comparing with pure nanoparticles. Agarose gel electrophoresis experiments show that DNA plasmids can be protected effectively against degradation of exonuclease and endonuclease. The efficiency of gene delivery was affected by the mass ratio of nanoparticle/DNA and the amount of nanoparticle/DNA complexes. We confirm that the most optimal mass ratio of nanoparticle/DNA is 1  :  1 by conducting a series of experiments. This work provides important experimental basis for the application of the magnetic nanoparticles on gene delivery to porcine somatic cells, which is significant for the achieving of breeding new transgenic cloned pigs by using somatic cell nuclear transfer technique.

  14. Water absorption in PEEK and PEI matrices. Contribution to the understanding of water-polar group interactions

    Science.gov (United States)

    Courvoisier, E.; Bicaba, Y.; Colin, X.

    2016-05-01

    The water absorption in two aromatic linear polymers (PEEK and PEI) was studied between 10% and 90% RH at 30, 50 and 70°C. It was found that these polymers display classical Henry and Fick's behaviors. Moreover, they have very close values of equilibrium water concentration C∞ and water diffusivity D presumably because their respective polar groups establish molecular interactions of the same nature with water. This assumption was checked from a literature compilation of values of C∞ and D for a large variety of linear and tridimensional polymers containing a single type of polar group. It was then evidenced that almost all types of carbonyl group (in particular, those belonging to imides, amides and ketones) have the same molar contribution to water absorption, except those belonging to esters which are much less hydrophilic. Furthermore, hydroxyl and sulfone groups are much more hydrophilic than carbonyl groups so that their molar contribution is located on another master curve. On this basis, semi-empirical structure/water transport property relationships were proposed. It was found that C∞ increases exponentially with the concentration of polar groups (presumably because water is doubly bonded), but also with the intensity of their molecular interactions with water. In contrast, D is inversely proportional to C∞, which means that polar group-water interactions slow down the rate of water diffusion.

  15. Surfactant effects on SF6 hydrate formation.

    Science.gov (United States)

    Lee, Bo Ram; Lee, Ju Dong; Lee, Hyun Ju; Ryu, Young Bok; Lee, Man Sig; Kim, Young Seok; Englezos, Peter; Kim, Myung Hyun; Kim, Yang Do

    2009-03-01

    Sulfur hexafluoride (SF(6)) has been widely used in a variety of industrial processes, but it is one of the most potent greenhouse gases. For this reason, it is necessary to separate or collect it from waste gas streams. One separation method is through hydrate crystal formation. In this study, SF(6) hydrate was formed in aqueous surfactant solutions of 0.00, 0.01, 0.05, 0.15 and 0.20 wt% to investigate the effects of surfactants on the hydrate formation rates. Three surfactants, Tween 20 (Tween), sodium dodecyl sulfate (SDS) and linear alkyl benzene sulfonate (LABS), were tested in a semi-batch stirred vessel at the constant temperature and pressures of 276.2 K and 0.78 MPa, respectively. All surfactants showed kinetic promoter behavior for SF(6) hydrate formation. It was also found that SF(6) hydrate formation proceeded in two stages with the second stage being the most rapid. In situ Raman spectroscopy analysis revealed that the increased gas consumption rate with the addition of surfactant was possibly due to the increased gas filling rate in the hydrate cavity.

  16. In Situ Raman Analyses of Natural Gas and Gas Hydrates at Hydrate Ridge, Oregon

    Science.gov (United States)

    Peltzer, E. T.; White, S. N.; Dunk, R. M.; Brewer, P. G.; Sherman, A. D.; Schmidt, K.; Hester, K. C.; Sloan, E. D.

    2004-12-01

    During a July 2004 cruise to Hydrate Ridge, Oregon, MBARI's sea-going laser Raman spectrometer was used to obtain in situ Raman spectra of natural gas hydrates and natural gas venting from the seafloor. This was the first in situ analysis of gas hydrates on the seafloor. The hydrate spectra were compared to laboratory analyses performed at the Center for Hydrate Research, Colorado School of Mines. The natural gas spectra were compared to MBARI gas chromatography (GC) analyses of gas samples collected at the same site. DORISS (Deep Ocean Raman In Situ Spectrometer) is a laboratory model laser Raman spectrometer from Kaiser Optical Systems, Inc modified at MBARI for deployment in the deep ocean. It has been successfully deployed to depths as great as 3600 m. Different sampling optics provide flexibility in adapting the instrument to a particular target of interest. An immersion optic was used to analyze natural gas venting from the seafloor at South Hydrate Ridge ( ˜780 m depth). An open-bottomed cube was placed over the vent to collect the gas. The immersion optic penetrated the side of the cube as did a small heater used to dissociate any hydrate formed during sample collection. To analyze solid hydrates at both South and North Hydrate Ridge ( ˜590 m depth), chunks of hydrate were excavated from the seafloor and collected in a glass cylinder with a mesh top. A stand-off optic was used to analyze the hydrate inside the cylinder. Due to the partial opacity of the hydrate and the small focal volume of the sampling optic, a precision underwater positioner (PUP) was used to focus the laser spot onto the hydrate. PUP is a stand-alone system with three degrees-of-freedom, capable of moving the DORISS probe head with a precision of 0.1 mm. In situ Raman analyses of the gas indicate that it is primarily methane. This is verified by GC analyses of samples collected from the same site. Other minor constituents (such as CO2 and higher hydrocarbons) are present but may be in

  17. Probing the Role of Zr Addition versus Textural Properties in Enhancement of CO 2 Adsorption Performance in Silica/PEI Composite Sorbents

    Energy Technology Data Exchange (ETDEWEB)

    Sakwa-Novak, Miles A.; Holewinski, Adam; Hoyt, Caroline B.; Yoo, Chun-Jae; Chai, Song-Hai; Dai, Sheng; Jones, Christopher W.

    2015-09-01

    Polymeric amines such as poly(ethylenimine) (PEI) supported on mesoporous oxides are promising candidate adsorbents for CO2 capture processes. An important aspect to the design and optimization of these materials is a fundamental understanding of how the properties of the oxide support such as pore structure, particle morphology, and surface properties affect the efficiency of the guest polymer in its interactions with CO2. Previously, the efficiency of impregnated PEI to adsorb CO2 was shown to increase upon the addition of Zr as a surface modifier in SBA-15. However, the efficacy of this method to tune the adsorption performance has not been explored in materials of differing textural and morphological nature. Here, these issues are directly addressed via the preparation of an array of SBA-15 support materials with varying textural and morphological properties, as well as varying content of zirconium doped into the material. Zirconium is incorporated into the SBA-15 either during the synthesis of the SBA-15, or postsynthetically via deposition of Zr species onto pure-silica SBA-15. The method of Zr incorporation alters the textural and morphological properties of the parent SBA-15 in different ways. Importantly, the CO2 capacity of SBA-15 impregnated with PEI increases by a maximum of ~60% with the quantity of doped Zr for a “standard” SBA-15 containing significant microporosity, while no increase in the CO2 capacity is observed upon Zr incorporation for an SBA-15 with reduced microporosity and a larger pore size, pore volume, and particle size. Finally, adsorbents supported on SBA-15 with controlled particle morphology show only modest increases in CO2 capacity upon inclusion of Zr to the silica framework. The data demonstrate that the textural and morphological properties of the support have a more significant impact on the ability of PEI to capture CO2 than the support surface composition.

  18. Effect of Hydrogen Reduction of Silver Ions on the Performance and Structure of New Solid Polymer Electrolyte PEI/Pebax2533/AgBF4 Composite Membranes

    Institute of Scientific and Technical Information of China (English)

    WANG Yanbei; REN Jizhong; LI Hui; DENG Maicun

    2013-01-01

    In this paper,the effect of hydrogen reduction of silver ions on the performance and structure of new solid polymer electrolyte polyetherimide (PEI)/Pebax2533 (Polynylon12/tetramethylene oxide block copolymer,PA12-PTMO)/AgBF4 composite membranes is investigated.For PEI/Pebax2533/AgBF4 composite membranes prepared with different AgBF4 concentration,the permeances of propylene and ethylene increase with the increase of AgBF4 concentration due to the carrier-facilitated transport,resulting in a high selectivity.But for propylene/propane mixture,the mixed-gas selectivity is lower than its ideal selectivity.The hydrogen reduction strongly influences the membrane performance,which causes the decrease of propylene permeance and the increase of propane permeance.With the increase of hydrogen reduction time,the membranes show a clearly color change from white to brow0n,yielding a great selectivity loss.The data of X-ray diffraction and FT-IR prove that silver ions are reduced to Ag after hydrogen reduction,and aggregated on the surface of PEI/Pebax2533/AgBF4 composite membranes.

  19. Experimental investigation of smectite hydration from the simulation of 001 X-ray diffraction lines. Implications for the characterization of mineralogical modifications of the 'argilite' from the Meuse - Haute Marne site as a result of a thermal perturbation; Etude experimentale de l'hydratation des smectites par simulation des raies OOl de diffraction des rayons X. Implications pour l'etude d'une perturbation thermique sur la mineralogie de l'argilite du site Meuse-Haute Marne

    Energy Technology Data Exchange (ETDEWEB)

    Ferrage, E

    2004-10-15

    The structural modifications affecting the reactive mineral constituents of the clay barriers (smectite) and possibly resulting from the thermal pulse related to nuclear waste storage are essentially limited to the amount and location of the layer charge deficit. These modifications likely impact the hydration properties of these minerals, and a specific methodology has thus been developed to describe, using simulation of X-ray diffraction profiles (001 reflections), these hydration properties and specifically the heterogeneity resulting from the inter-stratification of different layer types, each exhibiting a specific hydration state. The detailed study of the hydration properties of a low-charge montmorillonite (octahedral charge) has shown that the affinity of the interlayer cation for water rules the hydration state and the thickness of hydrated smectite layers. If the layer charge is increased, the transition between the different hydration states is shifted, following a water desorption isotherm, towards lower relative humidities. In addition, the hydration of studied beidellites (tetrahedral charge) was shown to be more heterogeneous than that of montmorillonites. The developed methodology also allowed describing the structural modifications resulting from a chemical perturbation (chlorinated anionic background, pH). Finally, the link between the thickness of elementary layers and the amount of interlayer water molecules has been evidenced. A new structure model has also been determined for these interlayer species allowing an improved description of their positional distribution in bi-hydrated interlayers. (author)

  20. mPEG-PCL-g-PEI聚合物纳米粒介导的小干扰RNA递送%Small interfering RNA delivery mediated by mPEG-PCL-g-PEI polymer nanoparticles

    Institute of Scientific and Technical Information of China (English)

    黄伟; 吕明; 高钟镐; 金明姬; 杨长青

    2011-01-01

    本文旨在合成小干扰核糖核酸(siRNA)递送载体聚合物聚乙二醇-聚己内酯-聚乙烯亚胺(mPEG-PCL-g-PEI),并探讨其体外siRNA递送性能.通过开环聚合反应制备二嵌段共聚物聚乙二醉-聚己内酯(mPEG-PCL-OH),将mPEG-PCL-OH的羟基末端依次化学转化为羟基(-COOH)和N-羟基琥珀酰亚胺(-NHS)生成mPEG-PCL-NHS,再将mPEG-PCL-NHS同枝化聚乙烯亚胺(PEI)反应生成三元共聚物mPEG-PCL-g-PEI.应用傅里叶变换红外光谱(FTIR)、核磁共振(NMR)和凝胶渗透色谱(GPC)对聚合物mPEG-PCL-g-PEI进行结构表征;通过复凝聚法制备mPEG-PCL-g-PEI/siRNA纳米粒,并测定其粒径和zeta电位;通过体外细胞MTT测试,比较mPEG-PCL-g-PEI/siRNA纳米粒和PEI/siRNA纳米粒的细胞毒性;通过体外细胞转染实验,考察不同N/P比的mPEG-PCL-g-PEI/siRNA纳米粒对萤火虫荧光素酶基因表达的抑制效率.结果表明,合成的三元聚合物(MPEG5k-PCL1.2k)1.4-g-PEI10k能压缩siRNA形成粒径为50~200 mn的纳米粒,其表面带有正电荷.MTT分析结果显示(mPEG5k-PCL1.2k)1.4-g-PEI10k/siRNA纳米粒的细胞毒性显著小于PEI10K/siRNA纳米粒(P< 0.05).当N/P比在50~150,萤火虫荧光素酶基因的表达显著下调(P<0.01).当N/P比为125时,萤火虫荧光素酶基因表达的抑制效率最大.聚合物mPEG-PCL-g-PEI能递送siRNA进入细胞,抑制靶基因表达,且细胞毒性较低,有望成为一种新型的siRNA递送载体.%The aim of this paper is to report the synthesis of the mPEG-PCL-g-PEI copolymers as small interfering RNA (siRNA) delivery vector, and exploration of the siRNA delivery potential of mPEG-PCL-g-PEI in vitro. The diblock copolymers mPEG-PCL-OH was prepared through the ring-opening polymerization. Then, the hydroxyl terminal (-OH) of mPEG-PCL-OH was chemically converted into the carboxy (-COOH) and N-hydroxysuccinimide (NHS) in turn to prepare mPEG-PCL-NHS. The branched PEI was reacted with mPEG-PCL-NHS to synthesize the ternary

  1. Effects of Fluid Saturation on Gas Recovery from Class-3 Hydrate Accumulations Using Depressurization: Case Study of Yuan-An Ridge Site in Southwestern Offshore Taiwan

    Science.gov (United States)

    Huang, Yi-Jyun; Wu, Cheng-Yueh; Hsieh, Bieng-Zih

    2016-04-01

    Gas hydrates are crystalline compounds in which guest gas molecules are trapped in host lattices of ice crystals. In Taiwan, the significant efforts have recently begun to evaluate the reserves of hydrate because the vast accumulations of gas hydrates had been recognized in southwestern offshore Taiwan. Class-3 type hydrate accumulations are referred to an isolated hydrate layer without an underlying zone of mobile fluids, and the entire hydrate layer may be well within the hydrate stability zone. The depressurization method is a useful dissociation method for gas production from Class-3 hydrate accumulations. The dissociation efficiency is controlled by the responses of hydrate to the propagating pressure disturbance, and the pressure propagation is relating to the amount (or saturation) of the mobile fluid in pore space of the hydrate layer. The purpose of this study is to study the effects of fluid saturation on the gas recovery from a class-3 hydrate accumulation using depressurization method. The case of a class-3 hydrate deposit of Yuan-An Ridge in southwestern offshore Taiwan is studied. The numerical method was used in this study. The reservoir simulator we used to study the dissociation of hydrate and the production of gas was the STARS simulator developed by CMG, which coupled heat transfer, geo-chemical, geo-mechanical, and multiphase fluid flow mechanisms. The study case of Yuan-An Ridge is located in southwestern offshore Taiwan. The hydrate deposit was found by the bottom simulating reflectors (BSRs). The geological structure of the studied hydrate deposit was digitized to build the geological model (grids) of the case. The formation parameters, phase behavior data, rock and fluid properties, and formation's initial conditions were assigned sequentially to grid blocks, and the completion and operation conditions were designed to wellbore blocks to finish the numerical model. The changes of reservoir pressure, temperature, saturation due to the hydrate

  2. Geochemistry of drill core headspace gases and its significance in gas hydrate drilling in Qilian Mountain permafrost

    Science.gov (United States)

    Lu, Zhengquan; Rao, Zhu; He, Jiaxiong; Zhu, Youhai; Zhang, Yongqin; Liu, Hui; Wang, Ting; Xue, Xiaohua

    2015-02-01

    Headspace gases from cores are sampled in the gas hydrate drilling well DK-8 in the Qilian Mountain permafrost. Gas components and carbon isotopes of methane from headspace gas samples are analyzed. The geochemical features of the headspace gases along the well profile are compared with occurrences of gas hydrate, and with the distribution of faults or fractures. Their geochemical significance is finally pointed out in gas hydrate occurrences and hydrocarbon migration. Results show high levels of hydrocarbon concentrations in the headspace gases at depths of 149-167 m, 228-299 m, 321-337 m and 360-380 m. Visible gas hydrate and its associated anomalies occur at 149-167 m and 228-299 m; the occurrence of high gas concentrations in core headspace gases was correlated to gas hydrate occurrences and their associated anomalies, especially in the shallow layers. Gas compositions, gas ratios of C1/ΣC1-5, C1/(C2 + C3), iC4/nC4, and iC5/nC5, and carbon isotopic compositions of methane (δ13C1, PDB‰) indicate that the headspace gases are mainly thermogenic, partly mixed with biodegraded thermogenic sources with small amounts derived from microbial sources. Faults or fracture zones are identified at intervals of 149-167 m, 228-299 m, 321-337 m, and near 360-380 m; significantly higher gas concentrations and lower dryness ratio were found in the headspace gases within the fault or fracture zones compared with areas above these zones. In the shallow zones, low dryness ratios were observed in headspace gases in zones where gas hydrate and faults or fracture zones were found, suggesting that faults or fracture zones serve as migration paths for gases in the deep layers and provide accumulation space for gas hydrate in the shallow layers of the Qilian Mountain permafrost.

  3. 沛县蔬菜生态系统能值分析%Emergy analysis of vegetable ecosystem in Pei County, Jiangsu Province

    Institute of Scientific and Technical Information of China (English)

    付伟; 蒋芳玲; 刘洪文; 吴震

    2011-01-01

    县蔬菜产业发展迅速;但净能值产出率仅略高于江苏省耕地生态系统净能值产出率,可能由于能值产出较高的先进技术推广不够;沛县蔬菜生态系统环境负荷率为1.43,低于江苏省耕地生态系统环境负荷率(2.83),且农药能值投入仅占0.21%,说明沛县蔬菜产业有较强的可持续发展能力和较大的发展潜力.为促进沛县蔬菜产业综合效益的提高和可持续发展,应进一步加强蔬菜产业基础设施及蔬菜产品加工业的建设,加大蔬菜产业的科学技术推广力度,增强沛县蔬菜生态经济系统的产出能力.%The theory of emergy analysis is based on the premise that all forms of energy are from the sun. Different and incomparable forms of energy are therefore unifiable into solar emjoules. In this study, environmental resources and economic characteristics of vegetable ecosystems in Pei County (one of the main production bases of vegetable in Jiangsu Province) were quantitatively analyzed using the theories and methods of ecosystem emergy analysis. A series of emergy indices were developed for evaluating the environment resources and development characters of the vegetable ecosystem in Pei County. These indices simultaneously provided scientific basis for sustainable development of vegetable industry in Pei County. The study showed that: in 2007, vegetable emergy input in Pei County was 1.22Χ 1021 sej. Industrial auxiliary energy input was 7.18Χ 1020 sej, accounting for 58.85% of the total vegetable ecosystem emergy, which suggested that the development of vegetable industry in Pei County relied mainly on industrial auxiliary energy, and had developed beyond traditional agriculture relied mainly on natural conditions. Vegetable ecosystem output in PeiCounty was 3.20Χ 1021 sej, accounting for 39.65% of total agriculture emergy yield, indicating that vegetable industry was one of the strongest pillars of industries in Pei County. Emergy outputs from

  4. Layer-by-Layer Assembly of a Self-Healing Anticorrosion Coating on Magnesium Alloys.

    Science.gov (United States)

    Fan, Fan; Zhou, Chunyu; Wang, Xu; Szpunar, Jerzy

    2015-12-16

    Fabrication of self-healing anticorrosion coatings has attracted attention as it has the ability to extend the service life and prevent the substrate from corrosive attack. However, a coating system with a rapid self-healing ability and an improved corrosion resistance is rarely reported. In this work, we developed a self-healing anticorrosion coating on a magnesium alloy (AZ31). The coating comprises a cerium-based conversion layer, a graphene oxide layer, and a branched poly(ethylene imine) (PEI)/poly(acrylic acid) (PAA) multilayer. We incorporated the graphene oxide as corrosion inhibitors and used the PEI/PAA multilayers to provide the self-healing ability to the coating systems. X-ray diffraction (XRD) and Raman spectroscopy were used to characterize the composition of the multilayers, and scanning electron microscopy (SEM) was used to analyze the surface morphology. The electrochemical impedance spectroscopy (EIS) results illustrate the improved corrosion resistance of the coating. The proposed coating also has a rapid self-healing ability in the presence of water.

  5. Corneal refractive index-hydration relationship by objective refractometry.

    Science.gov (United States)

    Patel, Sudi; Alió, Jorge L

    2012-11-01

    To compare an objective (VCH-1) with a manual subjective Abbé refractometer (MSAR) and evaluate the refractive index (RI)-hydration (H) relationship for the corneal stroma. Epithelial and endothelial layers were removed from a fresh postmortem ovine corneal buttons. RI was measured at both surfaces using (i) MSAR then (ii) VCH-1. The sample was weighed, slowly dehydrated under controlled conditions (2 h), and RI measures were repeated. Sample was oven dried (90°C) for 3 d to obtain dry weight and hydration at each episode of RI measurement. Average difference between individual pairs of measurements obtained using the two refractometers (ΔRI) was 0.00071 (standard deviation ± 0.0029, 95% confidence interval ± 0.0058). Root mean square difference between measurements obtained by the refractometers was 0.0024. There was no relationship between ΔRI and the mean of each measurement pair (r = 0.201, n = 40, p = 0.214). Linear regression revealed a significant relationship between RI and reciprocal of H at both surfaces as follows: anterior (i) RI = 1.355 + 0.111/H (r = -0.852, n = 20, p = <0.001), (ii) RI = 1.357 + 0.105/H (r = -0.849, n = 20, p = <0.001) and posterior (i) RI = 1.353 + 0.085/H (r = -0.882, n = 20, p = <0.001), (ii) RI = 1.350 + 0.088/H (r = -0.813, n = 20, p = <0.001). VCH-1 measurements are in good agreement with MSAR. RI at the anterior stroma was consistently higher suggesting hydration is lower by 1.10 units (6%) compared with the posterior stroma. Dehydration increased RI at both surfaces by similar rates. Current hypothetical models are useful for predicting RI from H for the posterior, but not the anterior, stroma.

  6. Using magnetic resonance imaging to monitor CH4 hydrate formation and spontaneous conversion of CH4 hydrate to CO2 hydrate in porous media.

    Science.gov (United States)

    Baldwin, Bernard A; Stevens, Jim; Howard, James J; Graue, Arne; Kvamme, Bjorn; Aspenes, Erick; Ersland, Geir; Husebø, Jarle; Zornes, David R

    2009-06-01

    Magnetic resonance imaging was used to monitor and quantify methane hydrate formation and exchange in porous media. Conversion of methane hydrate to carbon dioxide hydrate, when exposed to liquid carbon dioxide at 8.27 MPa and approximately 4 degrees C, was experimentally demonstrated with MRI data and verified by mass balance calculations of consumed volumes of gases and liquids. No detectable dissociation of the hydrate was measured during the exchange process.

  7. Controls on Gas Hydrate Formation and Dissociation

    Energy Technology Data Exchange (ETDEWEB)

    Miriam Kastner; Ian MacDonald

    2006-03-03

    The main objectives of the project were to monitor, characterize, and quantify in situ the rates of formation and dissociation of methane hydrates at and near the seafloor in the northern Gulf of Mexico, with a focus on the Bush Hill seafloor hydrate mound; to record the linkages between physical and chemical parameters of the deposits over the course of one year, by emphasizing the response of the hydrate mound to temperature and chemical perturbations; and to document the seafloor and water column environmental impacts of hydrate formation and dissociation. For these, monitoring the dynamics of gas hydrate formation and dissociation was required. The objectives were achieved by an integrated field and laboratory scientific study, particularly by monitoring in situ formation and dissociation of the outcropping gas hydrate mound and of the associated gas-rich sediments. In addition to monitoring with the MOSQUITOs, fluid flow rates and temperature, continuously sampling in situ pore fluids for the chemistry, and imaging the hydrate mound, pore fluids from cores, peepers and gas hydrate samples from the mound were as well sampled and analyzed for chemical and isotopic compositions. In order to determine the impact of gas hydrate dissociation and/or methane venting across the seafloor on the ocean and atmosphere, the overlying seawater was sampled and thoroughly analyzed chemically and for methane C isotope ratios. At Bush hill the pore fluid chemistry varies significantly over short distances as well as within some of the specific sites monitored for 440 days, and gas venting is primarily focused. The pore fluid chemistry in the tub-warm and mussel shell fields clearly documented active gas hydrate and authigenic carbonate formation during the monitoring period. The advecting fluid is depleted in sulfate, Ca Mg, and Sr and is rich in methane; at the main vent sites the fluid is methane supersaturated, thus bubble plumes form. The subsurface hydrology exhibits both

  8. Kinetic studies of gas hydrate formation with low-dosage hydrate inhibitors

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Pipeline blockage by gas hydrates is a serious problem in the petroleum industry.Low-dosage inhibitors have been developed for its cost-effective and environmentally acceptable characteristics.In a 1.072-L reactor with methane,ethane and propane gas mixture under the pressure of about 8.5 MPa at 4 °C,hydrate formation was investigated with low-dosage hydrate inhibitors PVP and GHI1,the change of the compressibility factor and gas composition in the gas phase was analyzed,the gas contents in hydrates were compared with PVP and GHI1 added,and the inhibition mechanism of GHI1 was discussed.The results show that PVP and GHI1 could effectively inhibit the growth of gas hydrates but not nucleation.Under the experimental condition with PVP added,methane and ethane occupied the small cavities of the hydrate crystal unit and the ability of ethane entering into hydrate cavities was weaker than that of methane.GHI1 could effectively inhibit molecules which could more readily form hydrates.The ether and hydroxy group of diethylene glycol monobutyl ether have the responsibility for stronger inhibition ability of GHI1 than PVP.

  9. Development of off-line layer chromatographic and total reflection X-ray fluorescence spectrometric methods for arsenic speciation

    Energy Technology Data Exchange (ETDEWEB)

    Mihucz, Victor G. [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary); Moricz, Agnes M. [L. Eoetvoes University, Department of Chemical Technology and Environmental Chemistry, P.O. Box 32, H-1518 Budapest (Hungary); Kroepfl, Krisztina [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Szikora, Szilvia [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Tatar, Eniko [Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary); L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, P.O. Box 32, H-1518 Budapest (Hungary); Parra, Lue Meru Marco [Universidad Centro-occidental Lisandro Alvarado, Decanato de Agronomia, Departamento de Quimica y Suelos Unidad de Analisis Instrumental, Apartado Postal 4076, Cabudare 3023 (Venezuela); Zaray, Gyula [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary) and Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary) and L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, P.O. Box 32, H-1518 Budapest (Hungary)]. E-mail: zaray@ludens.elte.hu

    2006-11-15

    Rapid and low cost off-line thin layer chromatography-total reflection X-ray fluorescence spectrometry and overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods have been developed for separation of 25 ng of each As(III), As(V), monomethyl arsonic acid and dimethylarsinic acid applying a PEI cellulose stationary phase on plastic sheets and a mixture of acetone/acetic acid/water = 2:1:1 (v/v/v) as eluent system. The type of eluent systems, the amounts (25-1000 ng) of As species applied to PEI cellulose plates, injection volume, development distance, and flow rate (in case of overpressured thin layer chromatography) were taken into consideration for the development of the chromatographic separation. Moreover, a microdigestion method employing nitric acid for the As spots containing PEI cellulose scratched from the developed plates divided into segments was developed for the subsequent total reflection X-ray fluorescence spectrometry analysis. The method was applied for analysis of root extracts of cucumber plants grown in As(III) containing modified Hoagland nutrient solution. Both As(III) and As(V) were detected by applying the proposed thin layer chromatography/overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods.

  10. Experimental characterization of production behavior accompanying the hydrate reformation in methane hydrate bearing sediments

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, T.; Kang, J.M.; Nguyen, H.T. [Seoul National Univ., Seoul (Korea, Republic of); Park, C. [Kangwon National Univ., (Korea, Republic of); Lee, J. [Korea Inst., of Geoscience and Mineral Resources (Korea, Republic of)

    2010-07-01

    This study investigated the production behaviour associated with gas hydrate reformation in methane hydrate-bearing sediment by hot-brine injection. A range of different temperature and brine injection rates were used to analyze the pressure and temperature distribution, the gas production behaviour and the movement of the dissociation front. The study showed that hydrate reformation reduces the production rate considerably at an early time. However, gas production increases during the dissociation, near the outlet because the dissociated methane around the inlet is consumed in reforming the hydrate and increases the hydrate saturation around the outlet. Higher temperature also increases the gas production rate and the speed of the dissociation front. 12 refs., 2 tabs., 4 figs.

  11. Studying methane migration mechanisms at Walker Ridge, Gulf of Mexico, via 3D methane hydrate reservoir modeling

    Energy Technology Data Exchange (ETDEWEB)

    Nole, Michael [University of Texas at Austin; Daigle, Hugh [University of Texas at Austin; Mohanty, Kishore [University of Texas at Austin; Cook, Ann [Ohio State University; Hillman, Jess [Ohio State University

    2015-12-15

    We have developed a 3D methane hydrate reservoir simulator to model marine methane hydrate systems. Our simulator couples highly nonlinear heat and mass transport equations and includes heterogeneous sedimentation, in-situ microbial methanogenesis, the influence of pore size contrast on solubility gradients, and the impact of salt exclusion from the hydrate phase on dissolved methane equilibrium in pore water. Using environmental parameters from Walker Ridge in the Gulf of Mexico, we first simulate hydrate formation in and around a thin, dipping, planar sand stratum surrounded by clay lithology as it is buried to 295mbsf. We find that with sufficient methane being supplied by organic methanogenesis in the clays, a 200x pore size contrast between clays and sands allows for a strong enough concentration gradient to significantly drop the concentration of methane hydrate in clays immediately surrounding a thin sand layer, a phenomenon that is observed in well log data. Building upon previous work, our simulations account for the increase in sand-clay solubility contrast with depth from about 1.6% near the top of the sediment column to 8.6% at depth, which leads to a progressive strengthening of the diffusive flux of methane with time. By including an exponentially decaying organic methanogenesis input to the clay lithology with depth, we see a decrease in the aqueous methane supplied to the clays surrounding the sand layer with time, which works to further enhance the contrast in hydrate saturation between the sand and surrounding clays. Significant diffusive methane transport is observed in a clay interval of about 11m above the sand layer and about 4m below it, which matches well log observations. The clay-sand pore size contrast alone is not enough to completely eliminate hydrate (as observed in logs), because the diffusive flux of aqueous methane due to a contrast in pore size occurs slower than the rate at which methane is supplied via organic methanogenesis

  12. Proton hydration in aqueous solution: Fourier transform infrared studies of HDO spectra

    Science.gov (United States)

    Śmiechowski, Maciej; Stangret, Janusz

    2006-11-01

    hydration layer, shared with the anion, as well as loosely bound water molecules interacting with free electron pairs of the central complex were detected in the affected spectra.

  13. Authigenic gypsum found in gas hydrate-associated sediments from Hydrate Ridge, the eastern North Pacific

    Institute of Scientific and Technical Information of China (English)

    WANG; Jiasheng; Erwin; Suess; Dirk; Rickert

    2004-01-01

    Characteristic gypsum micro-sphere and granular mass were discovered by binocular microscope in the gas hydrate-associated sediments at cores SO143-221 and SO143/TVG40-2A respectively on Hydrate Ridge of Cascadia margin, the eastern North Pacific. XRD patterns and EPA analyses show both micro-sphere and granular mass of the crystals have the typical peaks and the typical main chemical compositions of gypsum, although their weight percents are slightly less than the others in the non-gas hydrate-associated marine regions. SEM pictures show that the gypsum crystals have clear crystal boundaries, planes, edges and cleavages of gypsum in form either of single crystal or of twin crystals. In view of the fact that there are meanwhile gas hydrate-associated authigenic carbonates and SO42(-rich pore water in the same sediment cores, it could be inferred reasonably that the gypsums formed also authigenically in the gas hydrate-associated environment too, most probably at the interface between the downward advecting sulfate-rich seawater and the below gas hydrate, which spilled calcium during its formation on Hydrate Ridge. The two distinct forms of crystal intergrowth, which are the granular mass of series single gypsum crystals at core SO143/TVG40-2A and the microsphere of gypsum crystals accompanied with detrital components at core SO143-221 respectively, indicate that they precipitated most likely in different interstitial water dynamic environments. So, the distinct authigenic gypsums found in gas hydrate-associated sediments on Hydrate Ridge could also be believed as one of the parameters which could be used to indicate the presence of gas hydrate in an unknown marine sediment cores.

  14. Simulation experiments on gas production from hydrate-bearing sediments

    Institute of Scientific and Technical Information of China (English)

    GONG JianMing; CAO ZhiMin; CHEN JianWen; ZHANG Min; LI Jin; YANG GuiFang

    2009-01-01

    Experiments were made on 58 sediment samples from four sites (1244, 1245, 1250 and 1251) of ODP204 at five temperature points (25, 35, 45, 55 and 65℃) to simulate methane production from hy drate-bearing sediments. Simulation results from site 1244 show that the gas components consist mainly of methane and carbon dioxide, and heavy hydrocarbons more than C2+ cannot be detected.This site also gives results, similar to those from the other three, that the methane production is con trolled by experimental temperatures, generally reaching the maximum gas yields per gram sediment or TOC under lower temperatures (25 and 35℃). In other words, the methane amount could be related to the buried depth of sediments, given the close relation between the depth and temperature. Sediments less than 1200 m below seafioor are inferred to still act as a biogenic gas producer to pour methane into the present hydrate zone, while sedimentary layers more than 1200 m below seafloor have become too biogenically exhausted to offer any biogas, but instead they produce thermogenic gas to give ad ditional supply to the hydrate formation in the study area.

  15. METHANE HYDRATE PRODUCTION FROM ALASKAN PERMAFROST

    Energy Technology Data Exchange (ETDEWEB)

    Richard Sigal; Kent Newsham; Thomas Williams; Barry Freifeld; Timothy Kneafsey; Carl Sondergeld; Shandra Rai; Jonathan Kwan; Stephen Kirby; Robert Kleinberg; Doug Griffin

    2005-02-01

    Natural-gas hydrates have been encountered beneath the permafrost and considered a nuisance by the oil and gas industry for years. Engineers working in Russia, Canada and the USA have documented numerous drilling problems, including kicks and uncontrolled gas releases, in arctic regions. Information has been generated in laboratory studies pertaining to the extent, volume, chemistry and phase behavior of gas hydrates. Scientists studying hydrate potential agree that the potential is great--on the North Slope of Alaska alone, it has been estimated at 590 TCF. However, little information has been obtained on physical samples taken from actual rock containing hydrates. The work scope drilled and cored a well The Hot Ice No. 1 on Anadarko leases beginning in FY 2003 and completed in 2004. An on-site core analysis laboratory was built and utilized for determining the physical characteristics of the hydrates and surrounding rock. The well was drilled from a new Anadarko Arctic Platform that has a minimal footprint and environmental impact. The final efforts of the project are to correlate geology, geophysics, logs, and drilling and production data and provide this information to scientists developing reservoir models. No gas hydrates were encountered in this well; however, a wealth of information was generated and is contained in this report. The Hot Ice No. 1 well was drilled from the surface to a measured depth of 2300 ft. There was almost 100% core recovery from the bottom of surface casing at 107 ft to total depth. Based on the best estimate of the bottom of the methane hydrate stability zone (which used new data obtained from Hot Ice No. 1 and new analysis of data from adjacent wells), core was recovered over its complete range. Approximately 580 ft of porous, mostly frozen, sandstone and 155 of conglomerate were recovered in the Ugnu Formation and approximately 215 ft of porous sandstone were recovered in the West Sak Formation. There were gas shows in the bottom

  16. Experimental Determination of Refractive Index of Gas Hydrates

    DEFF Research Database (Denmark)

    Bylov, Martin; Rasmussen, Peter

    1997-01-01

    The refractive indexes of methane hydrate and natural gas hydrate have been experimentally determined. The refractive indexes were determined in an indirect manner making use of the fact that two non-absorbing materials will have the same refractive index if they cannot be distinguished visually....... For methane hydrate (structure I) the refractive index was found to be 1.346 and for natural gas hydrate (structure II) it was found to be 1.350. The measurements further suggest that the gas hydrate growth rate increases if the water has formed hydrates before. The induction time, on the other hand, seems...

  17. Complex admixtures of clathrate hydrates in a water desalination method

    Science.gov (United States)

    Simmons, Blake A.; Bradshaw, Robert W.; Dedrick, Daniel E.; Anderson, David W.

    2009-07-14

    Disclosed is a method that achieves water desalination by utilizing and optimizing clathrate hydrate phenomena. Clathrate hydrates are crystalline compounds of gas and water that desalinate water by excluding salt molecules during crystallization. Contacting a hydrate forming gaseous species with water will spontaneously form hydrates at specific temperatures and pressures through the extraction of water molecules from the bulk phase followed by crystallite nucleation. Subsequent dissociation of pure hydrates yields fresh water and, if operated correctly, allows the hydrate-forming gas to be efficiently recycled into the process stream.

  18. Molecular dynamics simulation for surface melting and self-preservation effect of methane hydrate

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The surface melting process of structure sI methane hydrate is simulated at T = 240, 260, 280, and 300 K using NVT molecular dynamics method. The simulation results show that a quasi-liquid layer will be formed during the melting process. The density distribution, translation, orientation, and dynamic properties of water molecules in the quasi-liquid layer are calculated as a function of the distance normal to the interface, which indicates the performance of quasi-liquid layer exhibits a continuous change from crystal-like to liquid-like. The quasi-liquid layer plays as a resistance of mass transfer restraining the diffusion of water and methane molecules during the melting process. The resistance of quasi-liquid layer will restrain methane molecules diffuse from hydrate phase to gas phase and slow the melting process, which can be considered as a possible mechanism of self-preservation effect. The performance of quasi-liquid layer is more crystal-like when the temperature is lower than the melt- ing-point of water, which will exhibit an obvious self-preservation. The self-preservation will weaken while the temperature is higher than the melting-point of water because of the liquid-like performance of the quasi-liquid layer.

  19. The fabrication of single-walled carbon nanotube/polyelectrolyte multilayer composites by layer-by-layer assembly and magnetic field assisted alignment

    Science.gov (United States)

    Tian, Ying; Park, Jin Gyu; Cheng, Qunfeng; Liang, Zhiyong; Zhang, Chuck; Wang, Ben

    2009-08-01

    Single-walled carbon nanotube (SWNT)/polymer composites are widely studied because of their potential for high mechanical performance and multifunctional applications. In order to realize highly ordered multilayer nanostructures, we combined the layer-by-layer (LBL) assembly method with magnetic force-induced alignment to fabricate SWNT/poly(ethylamine) (PEI) multilayer composites. The SWNTs were functionalized with the anionic surfactant sodium dodecylbenzenesulfonate (NaDDBS) to realize negative charge at pH>7, while the PEI is positively charged at pHPEI resin to form multilayer composites on a solid substrate polydimethylsiloxane. Since the fabricated thickness of each SWNT-NaDDBS/PEI bilayer is uniform (~150 nm), the multilayer film thickness can be strictly controlled via the number of deposition cycles. A high magnetic field (8.5 Tesla) was used to align the SWNTs during the LBL process. The resultant LBL composite samples demonstrated high SWNT loading of approximately 50 wt% and uniform distribution of SWNTs in the multilayer structures, which was verified using a quartz crystal microbalance. Good alignment was also realized and observed through using high magnetic fields to align the nanotubes during the LBL deposition process. The results indicate that the LBL/magnetic alignment approach has potential for fabricating nanotube composites with highly ordered nanostructures for multifunctional materials and device applications.

  20. First-principles elasticity of monocarboaluminate hydrates

    KAUST Repository

    Moon, J.

    2014-07-01

    The elasticity of monocarboaluminate hydrates, 3CaO·Al2O3·CaCO3·xH2O (x = 11 or 8), has been investigated by first-principles calculations. Previous experimental study revealed that the fully hydrated monocarboaluminate (x = 11) exhibits exceptionally low compressibility compared to other reported calcium aluminate hydrates. This stiff hydration product can contribute to the strength of concrete made with Portland cements containing calcium carbonates. In this study, full elastic tensors and mechanical properties of the crystal structures with different water contents (x = 11 or 8) are computed by first-principles methods based on density functional theory. The results indicate that the compressibility of monocarboaluminate is highly dependent on the water content in the interlayer region. The structure also becomes more isotropic with the addition of water molecules in this region. Since the monocarboaluminate is a key hydration product of limestone added cement, elasticity of the crystal is important to understand its mechanical impact on concrete. Besides, it is put forth that this theoretical calculation will be useful in predicting the elastic properties of other complex cementitous materials and the influence of ion exchange on compressibility.

  1. Interfacial phenomena in gas hydrate systems.

    Science.gov (United States)

    Aman, Zachary M; Koh, Carolyn A

    2016-03-21

    Gas hydrates are crystalline inclusion compounds, where molecular cages of water trap lighter species under specific thermodynamic conditions. Hydrates play an essential role in global energy systems, as both a hinderance when formed in traditional fuel production and a substantial resource when formed by nature. In both traditional and unconventional fuel production, hydrates share interfaces with a tremendous diversity of materials, including hydrocarbons, aqueous solutions, and inorganic solids. This article presents a state-of-the-art understanding of hydrate interfacial thermodynamics and growth kinetics, and the physiochemical controls that may be exerted on both. Specific attention is paid to the molecular structure and interactions of water, guest molecules, and hetero-molecules (e.g., surfactants) near the interface. Gas hydrate nucleation and growth mechanics are also presented, based on studies using a combination of molecular modeling, vibrational spectroscopy, and X-ray and neutron diffraction. The fundamental physical and chemical knowledge and methods presented in this review may be of value in probing parallel systems of crystal growth in solid inclusion compounds, crystal growth modifiers, emulsion stabilization, and reactive particle flow in solid slurries.

  2. The investigation of structure and IR spectra for hydrated potassium ion clusters K+(H2O)n=1-16 by density functional theory*

    Science.gov (United States)

    Zhu, Fayan; Zhou, Hongxia; Zhou, Yongquan; Miao, Juntao; Fang, Chunhui; Fang, Yan; Sun, Pengchao; Ge, Haiwen; Liu, Hongyan

    2016-11-01

    The hydration of K+(H2O)n has been widely studied and believe to be important for understanding solvent properties in biological and chemical systems. However, understanding the structure and the spectrum information K+(H2O)n with changing n is limited. Here, we investigated the clusters K+(H2O)n=1-16 and further studied the IR spectrums of the most stable clusters with density functional theory. The configuration, bond length, vibration frequency were given out. It shows that K+(H2O)8(H2O)n, a distorted square antiprism in inner layer, is the main configuration with hydration distance rK - OI 0.296 nm when the hydration number n is bigger than 8. The saturated hydration number is 8 in the first hydration layer and the water molecules of the second hydration sphere have little effect on the inner ones when n> 8. A detailed classification about the hydrated water molecules was made according to the role of acceptor or donor hydrogen bonding in clusters. The vibration frequency of the different kinds of water molecules were also detailly identified. The results are valuable for further determination of the K+(H2O)n clusters in aqueous solutions. Supplementary material in the form of one pdf file available from the Journal web page at http://dx.doi.org/10.1140/epjd/e2016-60529-7

  3. Stability evaluation of hydrate-bearing sediments during thermally-driven hydrate dissociation

    Science.gov (United States)

    Kwon, T.; Cho, G.; Santamarina, J.; Kim, H.; Lee, J.

    2009-12-01

    Hydrate-bearing sediments may destabilize spontaneously as part of geological processes, unavoidably during petroleum drilling/production operations, or intentionally as part of gas extraction from the hydrate itself. In all cases, high pore fluid pressure generation is anticipated during hydrate dissociation. This study examined how thermal changes destabilize gas hydrate-bearing sediments. First, an analytical formulation was derived for predicting fluid pressure evolution in hydrate-bearing sediments subjected to thermal stimulation without mass transfer. The formulation captures the self-preservation behavior, calculates the hydrate and free gas quantities during dissociation, considering effective stress-controlled sediment compressibility and gas solubility in aqueous phase. Pore fluid pressure generation is proportional to the initial hydrate fraction and the sediment bulk stiffness; is inversely proportional to the initial gas fraction and gas solubility; and is limited by changes in effective stress that cause the failure of the sediment. Second, the analytical formulation for hydrate dissociation was incorporated as a user-defined function into a verified finite difference code (FLAC2D). The underlying physical processes of hydrate-bearing sediments, including hydrate dissociation, self-preservation, pore pressure evolution, gas dissolution, and sediment volume expansion, were coupled with the thermal conduction, pore fluid flow, and mechanical response of sediments. We conducted the simulations for a duration of 20 years, assuming a constant-temperature wellbore transferred heat to the surrounding hydrate-bearing sediments, resulting in dissociation of methane hydrate in the well vicinity. The model predicted dissociation-induced excess pore fluid pressures which resulted in a large volume expansion and plastic deformation of the sediments. Furthermore, when the critical stress was reached, localized shear failure of the sediment around the borehole was

  4. Chemistry, isotopic composition, and origin of a methane-hydrogen sulfide hydrate at the Cascadia subduction zone

    Science.gov (United States)

    Kastner, M.; Kvenvolden, K.A.; Lorenson, T.D.

    1998-01-01

    Although the presence of extensive gas hydrate on the Cascadia margin, offshore from the western U.S. and Canada, has been inferred from marine seismic records and pore water chemistry, solid gas hydrate has only been found at one location. At Ocean Drilling Program (ODP) Site 892, offshore from central Oregon, gas hydrate was recovered close to the sediment - water interface at 2-19 m below the seafloor, (mbsf) at 670 m water depth. The gas hydrate occurs as elongated platy crystals or crystal aggregates, mostly disseminated irregularly, with higher concentrations occurring in discrete zones, thin layers, and/or veinlets parallel or oblique to the bedding. A 2-to 3-cm thick massive gas hydrate layer, parallel to bedding, was recovered at ???17 mbsf. Gas from a sample of this layer was composed of both CH4 and H2S. This sample is the first mixed-gas hydrate of CH4-H2S documented in ODP; it also contains ethane and minor amounts of CO2. Measured temperature of the recovered core ranged from 2 to - 18??C and are 6 to 8 degrees lower than in-situ temperatures. These temperature anomalies were caused by the partial dissociation of the CH4-H2S hydrate during recovery without a pressure core sampler. During this dissociation, toxic levels of H2S (??34S, +27.4???) were released. The ??13C values of the CH4 in the gas hydrate, -64.5 to -67.5???(PDB), together with ??D values of - 197 to - 199???(SMOW) indicate a primarily microbial source for the CH4. The ??18O value of the hydrate H2O is +2.9???(SMOW), comparable with the experimental fractionation factor for sea-ice. The unusual composition (CH4-H2S) and depth distribution (2-19 mbsf) of this gas hydrate indicate mixing between a methane-rich fluid with a pore fluid enriched in sulfide; at this site the former is advecting along an inclined fault into the active sulfate reduction zone. The facts that the CH4-H2S hydrate is primarily confined to the present day active sulfate reduction zone (2-19 mbsf), and that from here

  5. Modeling of Cation Binding in Hydrated 2:1 Clay Minerals - Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Smith, David E.

    2000-09-14

    Hydrated 2:1 clay minerals are high surface area, layered silicates that play a unique role in determining the fate of radionuclides in the environment. This project consisted of developing and implementing computer simulation methods for molecular characterization of the swelling and ion exchange properties of Hydrated 2:1 clay minerals, and the subsequent analysis and theoretical modeling with a view toward improving contaminant transport modeling as well as soil remediation and radionuclide containment strategies. Project results included the (a) development of simulation methods to treat clays under environmentally relevant conditions of variable water vapor pressure; (b) calculation of clay swelling thermodynamics as a function of interlayer ion size and charge (calculated quantities include immersion energies, free energies, and entropies of swelling); and (c) calculation of ion exchange free energies, including contributions from changing interlayer water contents and layer spacing.

  6. Gas Hydrate Deposits in the Cauvery-Mannar Offshore Basin, India

    Science.gov (United States)

    Dewangan, P.

    2015-12-01

    The analysis of geophysical and coring data from Mahanadi and Krishna-Godavari offshore basins, eastern continental margin of India, has established the presence of gas hydrate deposits; however, other promising petroliferous basins are relatively unexplored for gas hydrates. A collaborative program between GSI/MoM and CSIR-NIO was formulated to explore the Cauvery-Mannar offshore basin for gas hydrate deposits (Fig. 1a). High quality multi-channel reflection seismics (MCS) data were acquired with 3,000 cu. in airgun source array and 3 km long hydrophone streamer (240 channels) onboard R/V Samudra Ratnakar for gas hydrate studies. Other geophysical data such as gravity, magnetic and multibeam data were also acquired along with seismic data.After routine processing of seismic data, the bottom simulating reflectors (BSRs) are observed in the central and north-eastern part of the survey area. The BSRs are identified based on its characteristic features such as mimicking the seafloor, opposite polarity with respect to the seafloor and crosscutting the existing geological layers (Fig. 1b). At several locations, seismic signatures associated with free gas such as drop in interval velocity, pull-down structures, amplitude variation with offset (AVO) and attenuation are observed below the BSRs which confirm the presence of free gas in the study area. Acoustic chimneys are observed at some locations indicating vertical migration of the free gas. The observed seismic signatures established the presence of gas hydrates/free gas deposits in Cauvery-Mannar basin. Interestingly, BSRs appear to be distributed along the flanks of submarine canyon indicating the influence of geomorphology on the formation and distribution of gas hydrates.

  7. Methane hydrates in nature - Current knowledge and challenges

    Science.gov (United States)

    Collett, Timothy S.

    2014-01-01

    Recognizing the importance of methane hydrate research and the need for a coordinated effort, the United States Congress enacted the Methane Hydrate Research and Development Act of 2000. At the same time, the Ministry of International Trade and Industry in Japan launched a research program to develop plans for a methane hydrate exploratory drilling project in the Nankai Trough. India, China, the Republic of Korea, and other nations also have established large methane hydrate research and development programs. Government-funded scientific research drilling expeditions and production test studies have provided a wealth of information on the occurrence of methane hydrates in nature. Numerous studies have shown that the amount of gas stored as methane hydrates in the world may exceed the volume of known organic carbon sources. However, methane hydrates represent both a scientific and technical challenge, and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of methane hydrates in nature, (2) assessing the volume of natural gas stored within various methane hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural methane hydrates, (5) analyzing the methane hydrate role as a geohazard, (6) establishing the means to detect and characterize methane hydrate accumulations using geologic and geophysical data, and (7) establishing the thermodynamic phase equilibrium properties of methane hydrates as a function of temperature, pressure, and gas composition. The U.S. Department of Energy (DOE) and the Consortium for Ocean Leadership (COL) combined their efforts in 2012 to assess the contributions that scientific drilling has made and could continue to make to advance

  8. Apparatus investigates geological aspects of gas hydrates

    Science.gov (United States)

    Booth, J.S.; Winters, W.J.; Dillon, William P.

    1999-01-01

    The US Geological Survey has developed a laboratory research system which allows the study of the creation and dissociation of gas hydrates under deepwater conditions and with different sediment types and pore fluids. The system called GHASTLI (gas hydrate and sediment test laboratory instrument) comprises a pressure chamber which holds a sediment specimen, and which can simulate water depths to 2,500m and different sediment overburden. Seawater and gas flow through a sediment specimen can be precisely controlled and monitored. It can simulate a wide range of geology and processes and help to improve understanding of gas hydrate processes and aid prediction of geohazards, their control and potential use as an energy source. This article describes GHASTLI and how it is able to simulate natural conditions, focusing on fluid volume, acoustic velocity-compressional and shear wave, electric resistance, temperature, pore pressure, shear strength, and permeability.

  9. Simulation of Methane Recovery from Gas Hydrates Combined with Storing Carbon Dioxide as Hydrates

    Directory of Open Access Journals (Sweden)

    Georg Janicki

    2011-01-01

    Full Text Available In the medium term, gas hydrate reservoirs in the subsea sediment are intended as deposits for carbon dioxide (CO2 from fossil fuel consumption. This idea is supported by the thermodynamics of CO2 and methane (CH4 hydrates and the fact that CO2 hydrates are more stable than CH4 hydrates in a certain P-T range. The potential of producing methane by depressurization and/or by injecting CO2 is numerically studied in the frame of the SUGAR project. Simulations are performed with the commercial code STARS from CMG and the newly developed code HyReS (hydrate reservoir simulator especially designed for hydrate processing in the subsea sediment. HyReS is a nonisothermal multiphase Darcy flow model combined with thermodynamics and rate kinetics suitable for gas hydrate calculations. Two scenarios are considered: the depressurization of an area 1,000 m in diameter and a one/two-well scenario with CO2 injection. Realistic rates for injection and production are estimated, and limitations of these processes are discussed.

  10. An unusual zinc substrate-induced self-construction route to various hierarchical architectures of hydrated tungsten oxide.

    Science.gov (United States)

    Ma, De-Kun; Jiang, Jing-Lu; Huang, Jia-Rui; Yang, Dong-Peng; Cai, Ping; Zhang, Li-Jie; Huang, Shao-Ming

    2010-07-07

    A novel active zinc substrate-induced sequential self-construction method is presented for the fabrication of hydrated WO(3) hierarchical octahedrons, flakes, lanterns, and arresting sandwiched double-layer nanorods arrays architectures for the first time. Photocatalytic activity and gas sensing properties of the as-obtained various WO(3).0.33H(2)O architectures were studied as well.

  11. Nanostructure of Calcium Silicate Hydrates in Cements

    KAUST Repository

    Skinner, L. B.

    2010-05-11

    Calcium silicate hydrate (CSH) is the major volume phase in the matrix of Portland cement concrete. Total x-ray scattering measurements with synchrotron x rays on synthetic CSH(I) shows nanocrystalline ordering with a particle diameter of 3.5(5) nm, similar to a size-broadened 1.1 nm tobermorite crystal structure. The CSH component in hydrated tricalcium silicate is found to be similar to CSH(I). Only a slight bend and additional disorder within the CaO sheets is required to explain its nanocrystalline structure. © 2010 The American Physical Society.

  12. GLASS TRANSITION OF HYDRATED WHEAT GLIADIN POWDERS

    Institute of Scientific and Technical Information of China (English)

    Shao-min Sun; Li Zhao; Yi-hu Song; Qiang Zheng

    2011-01-01

    Modulated-temperature differential scanning calorimetric and dynamic mechanical analyses and dielectric spectroscopy were used to investigate the glass transition of hydrated wheat gliadin powders with moisture absorption ranged from 2.30 db% to 18.21 db%. Glass transition temperature (Tg) of dry wheat gliadin was estimated according to the GordonTaylor equation. Structural heterogeneity at high degrees of hydration was revealed in dielectric temperature and frequency spectra. The activation energies (Ea) of the two relaxations were calculated from Arrhenius equation.

  13. Component analysis of the protein hydration entropy

    Science.gov (United States)

    Chong, Song-Ho; Ham, Sihyun

    2012-05-01

    We report the development of an atomic decomposition method of the protein solvation entropy in water, which allows us to understand global change in the solvation entropy in terms of local changes in protein conformation as well as in hydration structure. This method can be implemented via a combined approach based on molecular dynamics simulation and integral-equation theory of liquids. An illustrative application is made to 42-residue amyloid-beta protein in water. We demonstrate how this method enables one to elucidate the molecular origin for the hydration entropy change upon conformational transitions of protein.

  14. Gas hydrate of Lake Baikal: Discovery and varieties

    Science.gov (United States)

    Khlystov, Oleg; De Batist, Marc; Shoji, Hitoshi; Hachikubo, Akihiro; Nishio, Shinya; Naudts, Lieven; Poort, Jeffrey; Khabuev, Andrey; Belousov, Oleg; Manakov, Andrey; Kalmychkov, Gennаdy

    2013-01-01

    This paper summarizes the results of recent gas-hydrate studies in Lake Baikal, the only fresh-water lake in the world containing gas hydrates in its sedimentary infill. We provide a historical overview of the different investigations and discoveries and highlight some recent breakthroughs in our understanding of the Baikal hydrate system. So far, 21 sites of gas hydrate occurrence have been discovered. Gas hydrates are of structures I and II, which are of thermogenic, microbial, and mixed origin. At the 15 sites, gas hydrates were found in mud volcanoes, and the rest six - near gas discharges. Additionally, depending on type of discharge and gas hydrate structure, they were visually different. Investigations using MIR submersibles allowed finding of gas hydrates at the bottom surface of Lake Baikal at the three sites.

  15. Monoamine oxidase B layer-by-layer film fabrication and characterization toward dopamine detection.

    Science.gov (United States)

    Miyazaki, Celina Massumi; Pereira, Tamyris Paschoal; Mascagni, Daniela Branco Tavares; de Moraes, Marli Leite; Ferreira, Marystela

    2016-01-01

    In this work nanostructured film composites of the monoamine oxidase B (MAO-B) enzyme, free or encapsulated in liposomes, were fabricated by the layer-by-layer (LbL) self-assembly technique, employing polyethylene imine (PEI) as polycation. Initially, the MAO-B enzyme was incorporated into liposomes in order to preserve its enzymatic structure ensuring their activity and catalytic stability. The LbL film growth was monitored by surface plasmon resonance (SPR) by gold resonance angle shift analysis after each bilayer deposition. Subsequently, the films were applied as amperometric biosensors for dopamine detection using Prussian Blue (PB) as the electron mediator. The biosensor fabricated by MAO-B incorporated into liposomes composed of DPPG:POPG in the ratio (1:4) (w/w) showed the best performance with a sensitivity of 0.86 (μA cm(-2))/(mmol L(-1)) and a detection limit of 0.33 mmol L(-1).

  16. Analysis of the hydration water around bovine serum albumin using terahertz coherent synchrotron radiation.

    Science.gov (United States)

    Bye, Jordan W; Meliga, Stefano; Ferachou, Denis; Cinque, Gianfelice; Zeitler, J Axel; Falconer, Robert J

    2014-01-09

    Terahertz spectroscopy was used to study the absorption of bovine serum albumin (BSA) in water. The Diamond Light Source operating in a low alpha mode generated coherent synchrotron radiation that covered a useable spectral bandwidth of 0.3-3.3 THz (10-110 cm(-1)). As the BSA concentration was raised, there was a nonlinear change in absorption inconsistent with Beer's law. At low BSA concentrations (0-1 mM), the absorption remained constant or rose slightly. Above a concentration of 1 mM BSA, a steady decrease in absorption was observed, which was followed by a plateau that started at 2.5 mM. Using a overlapping hydration layer model, the hydration layer was estimated to extend 15 Å from the protein. Calculation of the corrected absorption coefficient (αcorr) for the water around BSA by subtracting the excluded volume of the protein provides an alternative approach to studying the hydration layer that provides evidence for complexity in the population of water around BSA.

  17. Electrostatic Layer-by-Layer Assembly of Polycation and DNA Multilayer Films by Real-time Surface Plasmon ResonanceTechnique

    Institute of Scientific and Technical Information of China (English)

    PEI, Ren-Jun; CUI, Xiao-Qiang; YANG, Xiu-Rong; WANG, Er-Kang

    2001-01-01

    The assembly of alternating DNA and positively charged poly(dimethyldiallylammonium chloride) (PDDA) multilayer films by electrostatic layer-by-layer adsorption has been studied.Real time surface plasmon resonance (BIAcore) technique was used to characterize and monitor the formation of multilayer films in solution in real time continuously. The results indicate that the uniform multilayer can be obtained on the poly(ethylenimine) (PEI) coated substrate surface. The kinetics of the adsorption of DNA on PDDA surface was also studied by real-time BIAcore technique, and the observed rate constant was calculated using a Langmuir model (kobs= (1.28±0.08) ×10-2 s-1).

  18. Hydrate bearing clayey sediments: Formation and gas production concepts

    KAUST Repository

    Jang, Jaewon

    2016-06-20

    Hydro-thermo-chemo and mechanically coupled processes determine hydrate morphology and control gas production from hydrate-bearing sediments. Force balance, together with mass and energy conservation analyses anchored in published data provide robust asymptotic solutions that reflect governing processes in hydrate systems. Results demonstrate that hydrate segregation in clayey sediments results in a two-material system whereby hydrate lenses are surrounded by hydrate-free water-saturated clay. Hydrate saturation can reach ≈2% by concentrating the excess dissolved gas in the pore water and ≈20% from metabolizable carbon. Higher hydrate saturations are often found in natural sediments and imply methane transport by advection or diffusion processes. Hydrate dissociation is a strongly endothermic event; the available latent heat in a reservoir can sustain significant hydrate dissociation without triggering ice formation during depressurization. The volume of hydrate expands 2-to-4 times upon dissociation or CO2single bondCH4 replacement. Volume expansion can be controlled to maintain lenses open and to create new open mode discontinuities that favor gas recovery. Pore size is the most critical sediment parameter for hydrate formation and gas recovery and is controlled by the smallest grains in a sediment. Therefore any characterization must carefully consider the amount of fines and their associated mineralogy.

  19. Simulation of natural gas production from submarine gas hydrate deposits combined with carbon dioxide storage

    Science.gov (United States)

    Janicki, Georg; Schlüter, Stefan; Hennig, Torsten; Deerberg, Görge

    2013-04-01

    The recovery of methane from gas hydrate layers that have been detected in several submarine sediments and permafrost regions around the world so far is considered to be a promising measure to overcome future shortages in natural gas as fuel or raw material for chemical syntheses. Being aware that natural gas resources that can be exploited with conventional technologies are limited, research is going on to open up new sources and develop technologies to produce methane and other energy carriers. Thus various research programs have started since the early 1990s in Japan, USA, Canada, South Korea, India, China and Germany to investigate hydrate deposits and develop technologies to destabilize the hydrates and obtain the pure gas. In recent years, intensive research has focussed on the capture and storage of carbon dioxide from combustion processes to reduce climate change. While different natural or manmade reservoirs like deep aquifers, exhausted oil and gas deposits or other geological formations are considered to store gaseous or liquid carbon dioxide, the storage of carbon dioxide as hydrate in former methane hydrate fields is another promising alternative. Due to beneficial stability conditions, methane recovery may be well combined with CO2 storage in form of hydrates. This has been shown in several laboratory tests and simulations - technical field tests are still in preparation. Within the scope of the German research project »SUGAR«, different technological approaches are evaluated and compared by means of dynamic system simulations and analysis. Detailed mathematical models for the most relevant chemical and physical effects are developed. The basic mechanisms of gas hydrate formation/dissociation and heat and mass transport in porous media are considered and implemented into simulation programs like CMG STARS and COMSOL Multiphysics. New simulations based on field data have been carried out. The studies focus on the evaluation of the gas production

  20. IN-SITU SAMPLING AND CHARACTERIZATION OF NATURALLY OCCURRING MARINE METHANE HYDRATE USING THE D/V JOIDES RESOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Frank R. Rack; Tim Francis; Peter Schultheiss; Philip E. Long; Barry M. Freifeld

    2005-04-01

    The primary activities accomplished during this quarter were continued efforts to develop plans for Phase 2 of this cooperative agreement based on the evolving operational planning for IODP Expedition 311, which will use the JOIDES Resolution to study marine methane hydrates along the Cascadia margin, offshore Vancouver Island. IODP Expedition 311 has been designed to further constrain the models for the formation of marine gas hydrate in subduction zone accretionary prisms. The objectives include characterizing the deep origin of the methane, its upward transport, its incorporation in gas hydrate, and its subsequent loss to the seafloor. The main attention of this expedition is on the widespread seafloor-parallel layer of dispersed gas hydrate located just above the base of the predicted stability field. In a gas hydrate formation model, methane is carried upward through regional sediment or small-scale fracture permeability, driven by the tectonic consolidation of the accretionary prism. The upward moving methane is incorporated into the gas hydrate clathrate as it enters the methane hydrate stability zone. Also important is the focusing of a portion of the upward methane flux into localized plumes or channels to form concentrations of near-seafloor gas hydrate. The amount of gas hydrate in local concentrations near the seafloor is especially important for understanding the response of marine gas hydrate to climate change. The expedition includes coring and downhole measurements at five sites across the Northern Cascadia accretionary prism. The sites will track the history of methane in an accretionary prism from (1) its production by mainly microbiological processes over a thick sediment vertical extent, (2) its upward transport through regional or locally focused fluid flow, (3) its incorporation in the regional hydrate layer above the BSR or in local concentrations at or near the seafloor, (4) methane loss from the hydrate by upward diffusion, and (5) methane

  1. Isotropic, anisotropic, and borehole washout analyses in Gulf of Mexico Gas Hydrate Joint Industry Project Leg II, Alaminos Canyon well 21-A

    Science.gov (United States)

    Lee, Myung W.

    2012-01-01

    Through the use of three-dimensional seismic amplitude mapping, several gas hydrate prospects were identified in the Alaminos Canyon area of the Gulf of Mexico. Two of the prospects were drilled as part of the Gulf of Mexico Gas Hydrate Joint Industry Program Leg II in May 2009, and a suite of logging-while-drilling logs was acquired at each well site. Logging-while-drilling logs at the Alaminos Canyon 21–A site indicate that resistivities of approximately 2 ohm-meter and P-wave velocities of approximately 1.9 kilometers per second were measured in a possible gas-hydrate-bearing target sand interval between 540 and 632 feet below the sea floor. These values are slightly elevated relative to those measured in the hydrate-free sediment surrounding the sands. The initial well log analysis is inconclusive in determining the presence of gas hydrate in the logged sand interval, mainly because large washouts in the target interval degraded well log measurements. To assess gas-hydrate saturations, a method of compensating for the effect of washouts on the resistivity and acoustic velocities is required. To meet this need, a method is presented that models the washed-out portion of the borehole as a vertical layer filled with seawater (drilling fluid). Owing to the anisotropic nature of this geometry, the apparent anisotropic resistivities and velocities caused by the vertical layer are used to correct measured log values. By incorporating the conventional marine seismic data into the well log analysis of the washout-corrected well logs, the gas-hydrate saturation at well site AC21–A was estimated to be in the range of 13 percent. Because gas hydrates in the vertical fractures were observed, anisotropic rock physics models were also applied to estimate gas-hydrate saturations.

  2. Documenting channel features associated with gas hydrates in the Krishna-Godavari Basin, offshore India

    Science.gov (United States)

    Riedel, M.; Collett, T.S.; Shankar, U.

    2011-01-01

    During the India National Gas Hydrate Program (NGHP) Expedition 01 in 2006 significant sand and gas hydrate were recovered at Site NGHP-01-15 within the Krishna-Godavari Basin, East Coast off India. At the drill site NGHP-01-15, a 5-8m thick interval was found that is characterized by higher sand content than anywhere else at the site and within the KG Basin. Gas hydrate concentrations were determined to be 20-40% of the pore volume using wire-line electrical resistivity data as well as core-derived pore-fluid freshening trends. The gas hydrate-bearing interval was linked to a prominent seismic reflection observed in the 3D seismic data. This reflection event, mapped for about 1km2 south of the drill site, is bound by a fault at its northern limit that may act as migration conduit for free gas to enter the gas hydrate stability zone (GHSZ) and subsequently charge the sand-rich layer. On 3D and additional regional 2D seismic data a prominent channel system was imaged mainly by using the seismic instantaneous amplitude attribute. The channel can be clearly identified by changes in the seismic character of the channel fill (sand-rich) and pronounced levees (less sand content than in the fill, but higher than in surrounding mud-dominated sediments). The entire channel sequence (channel fill and levees) has been subsequently covered and back-filled with a more mud-prone sediment sequence. Where the levees intersect the base of the GHSZ, their reflection strengths are significantly increased to 5- to 6-times the surrounding reflection amplitudes. Using the 3D seismic data these high-amplitude reflection edges where linked to the gas hydrate-bearing layer at Site NGHP-01-15. Further south along the channel the same reflection elements representing the levees do not show similarly large reflection amplitudes. However, the channel system is still characterized by several high-amplitude reflection events (a few hundred meters wide and up to ~1km in extent) interpreted as gas

  3. Enhanced delivery of Paclitaxel using electrostatically-conjugated Herceptin-bearing PEI/PLGA nanoparticles against HER-positive breast cancer cells.

    Science.gov (United States)

    Yu, Kongtong; Zhao, Jinlong; Zhang, Zunkai; Gao, Yin; Zhou, Yulin; Teng, Lesheng; Li, Youxin

    2016-01-30

    We have developed a novel nanoparticle delivery system fabricated from polyethylenimine (PEI) and poly(d,l-lactide-co-glycolide) (PLGA), which were able to deliver the chemotherapeutic agent Paclitaxel, while the biomacromolecule Herceptin acted as a targeting ligand that was conjugated onto the surfaces of the nanoparticles via electrostatic interactions. In this study, these electrostatically-conjugated Herceptin-bearing PEI/PLGA nanoparticles (eHER-PPNs) were optimized and employed as vectors to target HER2-positive breast cancer cells. The eHER-PPNs had an average diameter of ∼ 280 nm and a neutral surface charge (1.00 ± 0.73 mV), which remained stable under physiological conditions. The anticancer effects of eHER-PPNs were investigated in HER2-positive BT474 cells and HER2-negative MCF7 cells. The eHER-PPNs showed enhanced cytotoxicity that was dependent on the receptor expression levels and the incubation time. These conjugated nanoparticles deliver Paclitaxel more efficiently (pHerceptin and the combined effects of these two monotherapies. Furthermore, the chemically-conjugated Herceptin-bearing PEI/PLGA nanoparticles (cHER-PPNs) were fabricated as a comparison. The eHER-PPNs exhibited lower cell viability (46.7%) than that of cHER-PPNs (65.1%). The targeting ability of eHER-PPNs was demonstrated through confocal microscopy images and flow cytometry, which showed that eHER-PPNs displayed higher cellular uptake efficiency (p<0.001) in comparison with cHER-PPNs. Therefore, eHER-PPNs could provide promising platforms for the delivery of therapeutic drugs against HER2-positive breast cancers.

  4. Synthesis and characterization of Fe3O4-PEG-LAC-chitosan-PEI nanoparticle as a survivin siRNA delivery system.

    Science.gov (United States)

    Arami, S; Rashidi, M R; Mahdavi, M; Fathi, M; Entezami, A A

    2017-03-01

    The limited effectiveness of the conventional methods for cancer treatment makes the researchers to find novel safe and effective therapeutic strategies. One of these strategies is to use small interfering RNAs (siRNAs). A major challenge here is the siRNA delivery into the cells. The purpose of this study was to design and prepare a biocompatible, biodegradable, and safe nanosized particle for siRNA delivery into human breast cancer MCF-7 and leukemia K562 cells. Chemically synthesized magnetic nanoparticles containing polyethyleneglycol-lactate polymer (PEG-LAC), chitosan, and polyethyleneimine (PEI) were successfully prepared and used as a gene delivery vehicle. The nanoparticles were characterized by Fourier transform infrared spectroscopy and zeta potential. The Fe3O4-PEG-LAC-chitosan-PEI nanoparticle showed efficient and stable survivin siRNA loading in gel retardation assay. The cytotoxicity of the prepared nanoparticle was studied using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide assay and was compared with that of mitoxantrone (MTX) in combination with the prepared siRNA delivery system to evaluate the possible synergic effect of MTX and survivin siRNA. The nanoparticles with and without noncomplementary siRNA showed low toxicity against both cell lines; however, a twofold decrease was observed in cell survival percent after MTX addition to MCF-7 cells treated with either nanoparticle itself or complexed with noncomplementary siRNA. While survivin siRNA nanoplex caused threefold decrease in the cell survival percent, its combination with MTX did not result in a significant increase in the cytotoxic effect. Therefore, Fe3O4-PEG-LAC-chitosan-PEI nanoparticle should be considered as a potential carrier for enhanced survivin siRNA delivery into MCF-7 and K562 cells.

  5. Numerical Investigation of Hydrate Dissociation Performance in the South China Sea with Different Horizontal Well Configurations

    Directory of Open Access Journals (Sweden)

    Jing-Chun Feng

    2014-07-01

    Full Text Available Based on the available measurement data and literature on the hydrate deposits of the South China Sea, a numerical simulation with a new dual horizontal well system has been carried out. Warm brine stimulation combined with depressurization is employed as the production method. Two horizontal wells were situated in the same horizontal plane and they were placed in the middle of the Hydrate-Bearing Layer (HBL. The warm brine is injected from the left well (LW into the reservoir, and the right well (RW acted as the producer under constant pressure. The simulation results show that the effects of hydrate dissociation rate, gas to water ratio, and energy ratio are all better than the previous work in which the dual horizontal wells are placed in the same vertical plane. In addition, the sensitivity analysis indicates that a higher injection rate can enhance the hydrate dissociation rate and gas production rate, while a lower injection rate gives a more favorable gas to water ratio and energy ratio.

  6. Study on the hydration product of cement in early age using TEM

    Institute of Scientific and Technical Information of China (English)

    HAN Song; YAN PeiYu; LIU RengGuang

    2012-01-01

    The morphology,crystallization and elemental composition of cement hydration products in early age including Ca(OH)2,CSH gel,AFt and AFm were investigated by transmission electron microscopy (TEM).Compared with the results from SEM and XRD,the TEM method and its advantage in the investigation of early hydration products were discussed.The results showed that TEM method is more accurate and reliable than SEM in the investigation of early hydration products.The CSH gel was confirmed to be amorphous foil-like shape product with a lot of crumples in early hydration age.Its Ca/Si ratio is 1.3±0.2.The morphology difference of AFt and AFm was clarified.AFt and AFm are both poly-crystal with layered structure,composed of disordered nano crystal.The size of nano crystal is less than 20 nm.The difference of Ca/Si ratio results between SEM and TEM was investigated,and its reason was explained.

  7. Gas Hydrates Accumulations on the South Shetland Continental Margin: New Detection Possibilities

    Directory of Open Access Journals (Sweden)

    V. D. Solovyov

    2011-01-01

    Full Text Available The results of investigations in 2006–2010 for hydrocarbon and gas hydrates on the Antarctic Peninsula continental margin are given. In 2004 and 2006, the marine geoelectric researches by methods of forming a short-pulsed electromagnetic field (FSPEF and vertical electric-resonance sounding (VERS had been conducted in this region. The “deposit” type anomaly was mapped by FSPEF survey, and anomalous polarized layers of “hydrocarbon deposit” type were chosen by VERS sounding within this anomaly on Antarctic margin in the region of UAS “Academician Vernadsky.” Anomalous zones of “gas hydrate deposit” type were detected on the South Shetland margin due to the special technology of satellite data processing and interpretation using. These results confirm the high gas hydrates potential of the West Antarctica region. Some practical results of the experimental approbation of these original technologies for the “direct” prospecting and exploration of hydrocarbon (HC and gas hydrates accumulations in different oil-and-gas bearing basins of Russia and Gulf of Mexico are proposed. The integration of satellite data processing and materials of FSPEF-VERS methods enable improving their efficiency for different geological and geophysical problems solving.

  8. The Use of Horizontal Wells in Gas Production from Hydrate Accumulations

    Energy Technology Data Exchange (ETDEWEB)

    Reagan, Matthew; Moridis, George J.; Reagan, Matthew T.; Zhang, Keni

    2008-04-15

    The amounts of hydrocarbon gases trapped in natural hydrate accumulations are enormous, leading to a recent interest in the evaluation of their potential as an energy source. Earlier studies have demonstrated that large volumes of gas can be readily produced at high rates for long times from gas hydrate accumulations by means of depressurization-induced dissociation, using conventional technology and vertical wells. The results of this numerical study indicate that the use of horizontal wells does not confer any practical advantages to gas production from Class 1 deposits. This is because of the large disparity in permeabilities between the hydrate layer (HL) and the underlying free gas zone, leading to a hydrate dissociation that proceeds in a horizontally dominant direction and is uniform along the length of the reservoir. When horizontal wells are placed near the base of the HL in Class 2 deposits, the delay in the evolution of a significant gas production rate outweighs their advantages, which include higher rates and the prevention of flow obstruction problems that often hamper the performance of vertical wells. Conversely, placement of a horizontal well near to top of the HL can lead to dramatic increases in gas production from Class 2 and Class 3 deposits over the corresponding production from vertical wells.

  9. Foam drilling in natural gas hydrate

    Directory of Open Access Journals (Sweden)

    Wei Na

    2015-01-01

    Full Text Available The key problem of foam drilling in natural gas hydrate is prediction of characteristic parameters of bottom hole. The simulation shows that when the well depth increases, the foam mass number reduces and the pressure increases. At the same depth, pressure in drill string is always higher than annulus. The research findings provide theoretical basis for safety control.

  10. Alkali binding in hydrated Portland cement paste

    NARCIS (Netherlands)

    Chen, W.; Brouwers, H.J.H.

    2010-01-01

    The alkali-binding capacity of C–S–H in hydrated Portland cement pastes is addressed in this study. The amount of bound alkalis in C–S–H is computed based on the alkali partition theories firstly proposed by Taylor (1987) and later further developed by Brouwers and Van Eijk (2003). Experimental data

  11. A positron annihilation study of hydrated DNA

    DEFF Research Database (Denmark)

    Warman, J. M.; Eldrup, Morten Mostgaard

    1986-01-01

    Positron annihilation measurements are reported for hydrated DNA as a function of water content and as a function of temperature (20 to -180.degree. C) for samples containing 10 and 50% wt of water. The ortho-positronium mean lifetime and its intensity show distinct variations with the degree...

  12. Hydration of protein–RNA recognition sites

    Science.gov (United States)

    Barik, Amita; Bahadur, Ranjit Prasad

    2014-01-01

    We investigate the role of water molecules in 89 protein–RNA complexes taken from the Protein Data Bank. Those with tRNA and single-stranded RNA are less hydrated than with duplex or ribosomal proteins. Protein–RNA interfaces are hydrated less than protein–DNA interfaces, but more than protein–protein interfaces. Majority of the waters at protein–RNA interfaces makes multiple H-bonds; however, a fraction do not make any. Those making H-bonds have preferences for the polar groups of RNA than its partner protein. The spatial distribution of waters makes interfaces with ribosomal proteins and single-stranded RNA relatively ‘dry’ than interfaces with tRNA and duplex RNA. In contrast to protein–DNA interfaces, mainly due to the presence of the 2′OH, the ribose in protein–RNA interfaces is hydrated more than the phosphate or the bases. The minor groove in protein–RNA interfaces is hydrated more than the major groove, while in protein–DNA interfaces it is reverse. The strands make the highest number of water-mediated H-bonds per unit interface area followed by the helices and the non-regular structures. The preserved waters at protein–RNA interfaces make higher number of H-bonds than the other waters. Preserved waters contribute toward the affinity in protein–RNA recognition and should be carefully treated while engineering protein–RNA interfaces. PMID:25114050

  13. Binding Hydrated Anions with Hydrophobic Pockets.

    Science.gov (United States)

    Sokkalingam, Punidha; Shraberg, Joshua; Rick, Steven W; Gibb, Bruce C

    2016-01-13

    Using a combination of isothermal titration calorimetry and quantum and molecular dynamics calculations, we demonstrate that relatively soft anions have an affinity for hydrophobic concavity. The results are consistent with the anions remaining partially hydrated upon binding, and suggest a novel strategy for anion recognition.

  14. Obsidian Hydration Dating in the Undergraduate Curriculum.

    Science.gov (United States)

    Manche, Emanuel P.; Lakatos, Stephen

    1986-01-01

    Provides an overview of obsidian hydration dating for the instructor by presenting: (1) principles of the method; (2) procedures; (3) applications; and (4) limitations. The theory of the method and one or more laboratory exercises can be easily introduced into the undergraduate geology curriculum. (JN)

  15. Obsidian Hydration Dating in the Undergraduate Curriculum.

    Science.gov (United States)

    Manche, Emanuel P.; Lakatos, Stephen

    1986-01-01

    Provides an overview of obsidian hydration dating for the instructor by presenting: (1) principles of the method; (2) procedures; (3) applications; and (4) limitations. The theory of the method and one or more laboratory exercises can be easily introduced into the undergraduate geology curriculum. (JN)

  16. [Terminal phase hydration, pain and delirium

    DEFF Research Database (Denmark)

    Heick, A.

    2009-01-01

    Hydration of the terminal patient may relieve confusion and complaints of "dry mouth". But it may worsen oedema of the brain, lungs, and extremities, worsen terminal rattling and cause a need for frequent changing of diapers. The decision of whether and how to treat a dying patient with fluids...

  17. Acoustic Determination of Methane Hydrate Disssociation Pressures

    Science.gov (United States)

    2011-07-01

    centered- cubic orientation which forms naturally in deep oceans from biogenic gases. It is worth not- ing that this molecular geometry can trap great...until January 2010. At that time, the hydrates were packed in a dewar with liquid nitrogen and shipped from the storage fa- cility at the Naval Research

  18. Hydration of Acetylene: A 125th Anniversary

    Science.gov (United States)

    Ponomarev, Dmitry A.; Shevchenko, Sergey M.

    2007-01-01

    The year 2006 is the 125th anniversary of a chemical reaction, the discovery of which by Mikhail Kucherov had a profound effect on the development of industrial chemistry in the 19-20th centuries. This was the hydration of alkynes catalyzed by mercury ions that made possible industrial production of acetaldehyde from acetylene. Historical…

  19. Anaerobic oxidation of methane above gas hydrates at Hydrate Ridge, NE Pacific Ocean

    DEFF Research Database (Denmark)

    Treude, T.; Boetius, A.; Knittel, K.;

    2003-01-01

    At Hydrate Ridge (HR), Cascadia convergent margin, surface sediments contain massive gas hydrates formed from methane that ascends together with fluids along faults from deeper reservoirs. Anaerobic oxidation of methane (AOM), mediated by a microbial consortium of archaea and sulfate-reducing...... bacteria, generates high concentrations of hydrogen sulfide in the surface sediments. The production of sulfide supports chemosynthetic communities that gain energy from sulfide oxidation. Depending on fluid flow, the surface communities are dominated either by the filamentous sulfur bacteria Beggiatoa...

  20. Modeling DNA hydration: comparison of calculated and experimental hydration properties of nuclic acid bases.

    Science.gov (United States)

    Poltev, V I; Malenkov, G G; Gonzalez, E J; Teplukhin, A V; Rein, R; Shibata, M; Miller, J H

    1996-02-01

    Hydration properties of individual nucleic acid bases were calculated and compared with the available experimental data. Three sets of classical potential functions (PF) used in simulations of nucleic acid hydration were juxtaposed: (i) the PF developed by Poltev and Malenkov (PM), (ii) the PF of Weiner and Kollman (WK), which together with Jorgensen's TIP3P water model are widely used in the AMBER program, and (iii) OPLS (optimized potentials for liquid simulations) developed by Jorgensen (J). The global minima of interaction energy of single water molecules with all the natural nucleic acid bases correspond to the formation of two water-base hydrogen bonds (water bridging of two hydrophilic atoms of the base). The energy values of these minima calculated via PM potentials are in somewhat better conformity with mass-spectrometric data than the values calculated via WK PF. OPLS gave much weaker water-base interactions for all compounds considered, thus these PF were not used in further computations. Monte Carlo simulations of the hydration of 9-methyladenine, 1-methyluracil and 1-methylthymine were performed in systems with 400 water molecules and periodic boundary conditions. Results of simulations with PM potentials give better agreement with experimental data on hydration energies than WK PF. Computations with PM PF of the hydration energy of keto and enol tautomers of 9-methylguanine can account for the shift in the tautomeric equilibrium of guanine in aqueous media to a dominance of the keto form in spite of nearly equal intrinsic stability of keto and enol tautomers. The results of guanine hydration computations are discussed in relation to mechanisms of base mispairing errors in nucleic acid biosynthesis. The data presented in this paper along with previous results on simulation of hydration shell structures in DNA duplex grooves provide ample evidence for the advantages of PM PF in studies of nucleic-acid hydration.

  1. Greetings: Professor Pei-Ming Ho won the 2011 AAA Award and Prof.Cenke Xu won the 2011 OYRA Award

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Professor Pei-Ming Ho won the 2011 Achievement in Asia Award (AAA),and Prof.Cenke Xu won the 2011 Outstanding Young Researcher Award (OYRA) of the Overseas Chinese Physics Association (OCPA).The OCPA AAA Award is given annually to Chinese physicists working in Asia in recognition of their outstanding achievements in physics,and the OYRA Award is given annually to a physicist of Chinese ethnicity working in North America,Europe,or other regions outside Asia,to encourage and to recognize the young researcher's contributions in physics.

  2. Direct measurement of methane hydrate composition along the hydrate equilibrium boundary

    Science.gov (United States)

    Circone, S.; Kirby, S.H.; Stern, L.A.

    2005-01-01

    The composition of methane hydrate, namely nW for CH 4??nWH2O, was directly measured along the hydrate equilibrium boundary under conditions of excess methane gas. Pressure and temperature conditions ranged from 1.9 to 9.7 MPa and 263 to 285 K. Within experimental error, there is no change in hydrate composition with increasing pressure along the equilibrium boundary, but nW may show a slight systematic decrease away from this boundary. A hydrate stoichiometry of n W = 5.81-6.10 H2O describes the entire range of measured values, with an average composition of CH4??5.99(??0.07) H2O along the equilibrium boundary. These results, consistent with previously measured values, are discussed with respect to the widely ranging values obtained by thermodynamic analysis. The relatively constant composition of methane hydrate over the geologically relevant pressure and temperature range investigated suggests that in situ methane hydrate compositions may be estimated with some confidence. ?? 2005 American Chemical Society.

  3. Clathrate Hydrates for Thermal Energy Storage in Buildings: Overview of Proper Hydrate-Forming Compounds

    Directory of Open Access Journals (Sweden)

    Beatrice Castellani

    2014-09-01

    Full Text Available Increasing energy costs are at the origin of the great progress in the field of phase change materials (PCMs. The present work aims at studying the application of clathrate hydrates as PCMs in buildings. Clathrate hydrates are crystalline structures in which guest molecules are enclosed in the crystal lattice of water molecules. Clathrate hydrates can form also at ambient pressure and present a high latent heat, and for this reason, they are good candidates for being used as PCMs. The parameter that makes a PCM suitable to be used in buildings is, first of all, a melting temperature at about 25 °C. The paper provides an overview of groups of clathrate hydrates, whose physical and chemical characteristics could meet the requirements needed for their application in buildings. Simulations with a dynamic building simulation tool are carried out to evaluate the performance of clathrate hydrates in enhancing thermal comfort through the moderation of summer temperature swings and, therefore, in reducing energy consumption. Simulations suggest that clathrate hydrates have a potential in terms of improvement of indoor thermal comfort and a reduction of energy consumption for cooling. Cooling effects of 0.5 °C and reduced overheating hours of up to 1.1% are predicted.

  4. MORPHOLOGY OF METHANE HYDRATE HOST SEDIMENTS.

    Energy Technology Data Exchange (ETDEWEB)

    JONES,K.W.; FENG,H.; TOMOV,S.; WINTER,W.J.; EATON,M.; MAHAJAN,D.

    2004-12-01

    Results from simulated experiments in several laboratories show that host sediments influence hydrate formation in accord with known heterogeneity of host sediments at sites of gas hydrate occurrence (1). For example, in Mackenzie Delta, NWT Canada (Mallik 2L-38 well), coarser-grained units (pore-filling model) are found whereas in the Gulf of Mexico, the found hydrate samples do not appear to be lithologically controlled. We have initiated a systematic study of sediments, initially focusing on samples from various depths at a specific site, to establish a correlation with hydrate occurrence (or variations thereof) to establish differences in their microstructure, porosity, and other associated properties. The synchrotron computed microtomography (CMT) set-up at the X-27A tomography beam line at the National Synchrotron Light Source (NSLS), Brookhaven National Laboratory was used as a tool to study sediments from Blake Ridge at three sub bottom depths of 0.2, 50, and 667 meters. Results from the tomographic analysis of the deepest sample (667 m) are presented here to illustrate how tomography can be used to obtain new insights into the structures of methane hydrate host sediments. The investigation shows the internal grain/pore space resolution in the microstructure and a 3-D visualization of the connecting pathways obtained following data segmentation into pore space and grains within the sediment sample. The analysis gives the sample porosity, specific surface area, mean particle size, and tortuosity, as well. An earlier report on the experimental program has been given by Mahajan et al. (2).

  5. Long-term results of interventional treatment of large unresectable hepatocellular carcinoma (HCC): significant survival benefit from combined transcatheter arterial chemoembolization (TACE) and percutaneous ethanol injection (PEI) compared to TACE monotherapy; Langzeitergebnisse der interventionellen Therapie von grossen, inoperablen hepatozellulaeren Karzinomen (HCC): signifikanter Ueberlebensvorteil von transarterieller Chemoembolisation (TACE) und perkutaner Ethanolinjektion (PEI) gegenueber der TACE-Monotherapie

    Energy Technology Data Exchange (ETDEWEB)

    Lubienski, A.; Bitsch, R.G.; Grenacher, L.; Kauffmann, G.W. [Radiologische Universitaetsklinik Heidelberg, Abt. Radiodiagnostik, Heidelberg (Germany); Schemmer, P. [Chirurgische Universitaetsklinik Heidelberg (Germany); Duex, M. [Radiologisches Zentralinstitut Krankenhaus Nordwest Frankfurt (Germany)

    2004-12-01

    Purpose: A retrospective analysis of long-term efficacy of combined transcatheter arterial chemoembolization (TACE) and percutaneous ethanol injection (PEI) and TACE monotherapy was conducted in patients with large, non-resectable hepatocellular carcinoma (HCC). Methods and Materials: Fifty patients with large, unresectable HCC lesions underwent selective TACE. Liver cirrhosis was present in 42 patients, due to alcohol abuse (n = 22) and viral infection (n = 17). In three patients, the underlying cause for liver cirrhosis remained unclear. Child A cirrhosis was found in 22 and Child B cirrhosis in 20 patients. Repeated and combined TACE and PEI were performed in 22 patients and repeated TACE monotherapy was performed in 28 patients. Survival and complication rates were determined and compared. Results: The 6-, 12-, 24- and 36-month survival rates were 61%, 21%, 4%, and 4% for TACE monotherapy and 77%, 55%, 39% and 22% for combined TACE and PEI (Kaplan-Meier method). The kind of treatment significantly affected the survival rate (p=0.002 log-rank test). Severe side effects were present in two patients of the monotherapy group and in three patients of the combination therapy group. (orig.)

  6. China's Research on Non-conventional Energy Resources- Gas Hydrate

    Institute of Scientific and Technical Information of China (English)

    Pu Ming; Ma Jianguo

    2002-01-01

    @@ Methane exists in ice-like formations called gas hydrate. Hydrate traps methane molecules inside a cage of frozen water. The magnitude of this previously unknown global storehouse of methane is truly staggering and has raised serious inquiry into the possibility of using methane hydrate as a substitute source of energy for oil and conventional natural gas. According to the estimation by PGC, gas hydrate deposits amount to 7.6 × 1018m3 and contain more than twice as much organic carbon as all the world's coal, oil and non-hydrate natural gas combined.

  7. A comparison of the effectiveness of cationic polymers poly-L-lysine (PLL) and polyethylenimine (PEI) for non-viral delivery of plasmid DNA to bone marrow stromal cells (BMSC).

    Science.gov (United States)

    Farrell, Laura-Lee; Pepin, Joel; Kucharski, Cezary; Lin, Xiaoyue; Xu, Zhenghe; Uludag, Hasan

    2007-03-01

    Bone marrow stromal cells (BMSC) represent an important cell phenotype for pursuit of successful gene therapy. Non-viral methods to enable expression of exogenous genes in BMSC will accelerate clinical application of gene therapy, without the concerns associated with the viral means of gene transfer. Towards this end, this study investigated the potential of cationic polymers poly-L-lysine (PLL) and branched polyethylenimine (PEI) as gene carriers for modification of BMSC. Both polymers rapidly (approximately 30 min) condensed a 4.2 kb Enhanced Green Fluorescent Protein (pEGFP-N2) plasmid into 100-200 nm particles. PLL and PEI were both readily internalized with BMSC with >80% of BMSC exhibiting polymer uptake by flow cytometric analysis. The relative uptake of PEI, however, was significantly higher as compared to the PLL. The majority of the BMSC (>60%) exhibited nuclear presence of the polymers as analyzed by fluorescent microscopy. Although both polymers were able to deliver the pEGFP-N2 into the cells under microscopic evaluation, only a small fraction of the cells (PLL and PEI readily displayed cellular uptake, but PEI was more effective in delivering plasmid DNA intracellularly, which was likely the underlying basis for a more sustained gene expression.

  8. Indian National Gas Hydrate Program Expedition 01 report

    Science.gov (United States)

    Collett, Timothy S.; Riedel, M.; Boswell, R.; Presley, J.; Kumar, P.; Sathe, A.; Sethi, A.; Lall, M.; ,

    2015-01-01

    Gas hydrate is a naturally occurring “ice-like” combination of natural gas and water that has the potential to serve as an immense resource of natural gas from the world’s oceans and polar regions. However, gas-hydrate recovery is both a scientific and a technical challenge and much remains to be learned about the geologic, engineering, and economic factors controlling the ultimate energy resource potential of gas hydrate. The amount of natural gas contained in the world’s gas-hydrate accumulations is enormous, but these estimates are speculative and range over three orders of magnitude from about 2,800 to 8,000,000 trillion cubic meters of gas. By comparison, conventional natural gas accumulations (reserves and undiscovered, technically recoverable resources) for the world are estimated at approximately 440 trillion cubic meters. Gas recovery from gas hydrate is hindered because the gas is in a solid form and because gas hydrate commonly occurs in remote Arctic and deep marine environments. Proposed methods of gas recovery from gas hydrate generally deal with disassociating or “melting” in situ gas hydrate by heating the reservoir beyond the temperature of gas-hydrate formation, or decreasing the reservoir pressure below hydrate equilibrium. The pace of energy-related gas hydrate assessment projects has accelerated over the past several years.

  9. Solid state interconversion between anhydrous norfloxacin and its hydrates.

    Science.gov (United States)

    Chongcharoen, Wanchai; Byrn, Stephen R; Sutanthavibul, Narueporn

    2008-01-01

    This work is focused on characterizing and evaluating the solid state interconversion of norfloxacin (NF) hydrates. Four stoichiometric NF hydrates, dihydrate, hemipentahydrate, trihydrate, pentahydrate and a disordered NF state, were generated by various methods and characterized by X-ray powder diffractometry (XRPD), thermal analysis and Karl Fisher titrimetry. XRPD patterns of all NF hydrates exhibited crystalline structures. NF hydrate conversion was studied with respect to mild elevated temperature and various degrees of moisture levels. NF hydrates transformed to anhydrous NF Form A after gentle heating at 60 degrees C for 48 h except dihydrate and trihydrate where mixture in XRPD patterns between anhydrous NF Form A and former structures existed. Desiccation of NF hydrates at 0% RH for 7 days resulted in only partial removal of water molecules from the hydrated structures. The hydrated transitional phase and the disordered NF state were obtained from the incomplete dehydration of NF hydrates after thermal treatment and pentahydrate NF after desiccation, respectively. Anhydrous NF Form A and NF hydrates transformed to pentahydrate NF when exposed to high moisture environment except dihydrate. In conclusion, surrounding moisture levels, temperatures and the duration of exposure strongly influenced the interconversion pathways and stoichiometry of anhydrous NF and its hydrates. (c) 2007 Wiley-Liss, Inc.

  10. Characterization of un-hydrated and hydrated BioAggregate™ and MTA Angelus™.

    Science.gov (United States)

    Camilleri, J; Sorrentino, F; Damidot, D

    2015-04-01

    BioAggregate™ is a novel material introduced for use as a root-end filling material. It is tricalcium silicate-based, free of aluminium and uses tantalum oxide as radiopacifier. BioAggregate contains additives to enhance the material performance. The purpose of this research was to characterize the un-hydrated and hydrated forms of BioAggregate using a combination of techniques, verify whether the additives if present affect the properties of the set material and compare these properties to those of MTA Angelus™. Un-hydrated and hydrated BioAggregate and MTA Angelus were assessed. Un-hydrated cement was tested for chemical composition, specific surface area, mineralogy and kinetics of hydration. The set material was investigated for mineralogy, microstructure and bioactivity. Scanning electron microscopy, X-ray energy dispersive spectroscopic analysis, X-ray fluorescence spectroscopy, X-ray diffraction and isothermal calorimetry were employed. The specific surface area was investigated using a gas adsorption method with nitrogen as the probe. BioAggregate was composed of tricalcium silicate, tantalum oxide, calcium phosphate and silicon dioxide and was free of aluminium. On hydration, the tricalcium silicate produced calcium silicate hydrate and calcium hydroxide. The former was deposited around the cement grains, while the latter reacted with the silicon dioxide to form additional calcium silicate hydrate. This resulted in reduction of calcium hydroxide in the aged cement. MTA Angelus reacted in a similar fashion; however, since it contained no additives, the calcium hydroxide was still present in the aged cement. Bioactivity was demonstrated by deposition of hydroxyapatite. BioAggregate exhibited a high specific surface area. Nevertheless, the reactivity determined by isothermal calorimetry appeared to be slow compared to MTA Angelus. The tantalum oxide as opposed to bismuth oxide was inert, and tantalum was not leached in solution. BioAggregate exhibited

  11. Natural Gas Evolution in a Gas Hydrate Melt: Effect of Thermodynamic Hydrate Inhibitors.

    Science.gov (United States)

    Sujith, K S; Ramachandran, C N

    2017-01-12

    Natural gas extraction from gas hydrate sediments by injection of hydrate inhibitors involves the decomposition of hydrates. The evolution of dissolved gas from the hydrate melt is an important step in the extraction process. Using classical molecular dynamics simulations, we study the evolution of dissolved methane from its hydrate melt in the presence of two thermodynamic hydrate inhibitors, NaCl and CH3OH. An increase in the concentration of hydrate inhibitors is found to promote the nucleation of methane nanobubbles in the hydrate melt. Whereas NaCl promotes bubble formation by enhancing the hydrophobic interaction between aqueous CH4 molecules, CH3OH molecules assist bubble formation by stabilizing CH4 bubble nuclei formed in the solution. The CH3OH molecules accumulate around the nuclei leading to a decrease in the surface tension at their interface with water. The nanobubbles formed are found to be highly dynamic with frequent exchange of CH4 molecules between the bubble and the surrounding liquid. A quantitative analysis of the dynamic behavior of the bubble is performed by introducing a unit step function whose value depends on the location of CH4 molecules with respect to the bubble. It is observed that an increase in the concentration of thermodynamic hydrate inhibitors reduces the exchange process, making the bubble less dynamic. It is also found that for a given concentration of the inhibitor, larger bubbles are less dynamic compared to smaller ones. The dependence of the dynamic nature of nanobubbles on bubble size and inhibitor concentration is correlated with the solubility of CH4 and the Laplace pressure within the bubble. The effect of CO2 on the formation of nanobubble in the CH4-CO2 mixed gas hydrate melt in the presence of inhibitors is also examined. The simulations show that the presence of CO2 molecules significantly reduces the induction time for methane nanobubble nucleation. The role of CO2 in the early nucleation of bubble is explained

  12. Towards a green hydrate inhibitor: imaging antifreeze proteins on clathrates.

    Directory of Open Access Journals (Sweden)

    Raimond Gordienko

    Full Text Available The formation of hydrate plugs in oil and gas pipelines is a serious industrial problem and recently there has been an increased interest in the use of alternative hydrate inhibitors as substitutes for thermodynamic inhibitors like methanol. We show here that antifreeze proteins (AFPs possess the ability to modify structure II (sII tetrahydrofuran (THF hydrate crystal morphologies by adhering to the hydrate surface and inhibiting growth in a similar fashion to the kinetic inhibitor poly-N-vinylpyrrolidone (PVP. The effects of AFPs on the formation and growth rate of high-pressure sII gas mix hydrate demonstrated that AFPs are superior hydrate inhibitors compared to PVP. These results indicate that AFPs may be suitable for the study of new inhibitor systems and represent an important step towards the development of biologically-based hydrate inhibitors.

  13. Water retention curve for hydrate-bearing sediments

    Science.gov (United States)

    Dai, Sheng; Santamarina, J. Carlos

    2013-11-01

    water retention curve plays a central role in numerical algorithms that model hydrate dissociation in sediments. The determination of the water retention curve for hydrate-bearing sediments faces experimental difficulties, and most studies assume constant water retention curves regardless of hydrate saturation. This study employs network model simulation to investigate the water retention curve for hydrate-bearing sediments. Results show that (1) hydrate in pores shifts the curve to higher capillary pressures and the air entry pressure increases as a power function of hydrate saturation; (2) the air entry pressure is lower in sediments with patchy rather than distributed hydrate, with higher pore size variation and pore connectivity or with lower specimen slenderness along the flow direction; and (3) smaller specimens render higher variance in computed water retention curves, especially at high water saturation Sw > 0.7. Results are relevant to other sediment pore processes such as bioclogging and mineral precipitation.

  14. A Wearable Hydration Sensor with Conformal Nanowire Electrodes.

    Science.gov (United States)

    Yao, Shanshan; Myers, Amanda; Malhotra, Abhishek; Lin, Feiyan; Bozkurt, Alper; Muth, John F; Zhu, Yong

    2017-01-27

    A wearable skin hydration sensor in the form of a capacitor is demonstrated based on skin impedance measurement. The capacitor consists of two interdigitated or parallel electrodes that are made of silver nanowires (AgNWs) in a polydimethylsiloxane (PDMS) matrix. The flexible and stretchable nature of the AgNW/PDMS electrode allows conformal contact to the skin. The hydration sensor is insensitive to the external humidity change and is calibrated against a commercial skin hydration system on an artificial skin over a wide hydration range. The hydration sensor is packaged into a flexible wristband, together with a network analyzer chip, a button cell battery, and an ultralow power microprocessor with Bluetooth. In addition, a chest patch consisting of a strain sensor, three electrocardiography electrodes, and a skin hydration sensor is developed for multimodal sensing. The wearable wristband and chest patch may be used for low-cost, wireless, and continuous monitoring of skin hydration and other health parameters.

  15. Comparative Assessment of Advanced Gay Hydrate Production Methods

    Energy Technology Data Exchange (ETDEWEB)

    M. D. White; B. P. McGrail; S. K. Wurstner

    2009-06-30

    Displacing natural gas and petroleum with carbon dioxide is a proven technology for producing conventional geologic hydrocarbon reservoirs, and producing additional yields from abandoned or partially produced petroleum reservoirs. Extending this concept to natural gas hydrate production offers the potential to enhance gas hydrate recovery with concomitant permanent geologic sequestration. Numerical simulation was used to assess a suite of carbon dioxide injection techniques for producing gas hydrates from a variety of geologic deposit types. Secondary hydrate formation was found to inhibit contact of the injected CO{sub 2} regardless of injectate phase state, thus diminishing the exchange rate due to pore clogging and hydrate zone bypass of the injected fluids. Additional work is needed to develop methods of artificially introducing high-permeability pathways in gas hydrate zones if injection of CO{sub 2} in either gas, liquid, or micro-emulsion form is to be more effective in enhancing gas hydrate production rates.

  16. In-situ gas hydrate hydrate saturation estimated from various well logs at the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope

    Science.gov (United States)

    Lee, M.W.; Collett, T.S.

    2011-01-01

    In 2006, the U.S. Geological Survey (USGS) completed detailed analysis and interpretation of available 2-D and 3-D seismic data and proposed a viable method for identifying sub-permafrost gas hydrate prospects within the gas hydrate stability zone in the Milne Point area of northern Alaska. To validate the predictions of the USGS and to acquire critical reservoir data needed to develop a long-term production testing program, a well was drilled at the Mount Elbert prospect in February, 2007. Numerous well log data and cores were acquired to estimate in-situ gas hydrate saturations and reservoir properties.Gas hydrate saturations were estimated from various well logs such as nuclear magnetic resonance (NMR), P- and S-wave velocity, and electrical resistivity logs along with pore-water salinity. Gas hydrate saturations from the NMR log agree well with those estimated from P- and S-wave velocity data. Because of the low salinity of the connate water and the low formation temperature, the resistivity of connate water is comparable to that of shale. Therefore, the effect of clay should be accounted for to accurately estimate gas hydrate saturations from the resistivity data. Two highly gas hydrate-saturated intervals are identified - an upper ???43 ft zone with an average gas hydrate saturation of 54% and a lower ???53 ft zone with an average gas hydrate saturation of 50%; both zones reach a maximum of about 75% saturation. ?? 2009.

  17. Efficacious cellular codelivery of doxorubicin and EGFP siRNA mediated by the composition of PLGA and PEI protected gold nanoparticles.

    Science.gov (United States)

    Kumar, Krishan; Vulugundam, Gururaja; Jaiswal, Pradeep Kumar; Shyamlal, Bharti Rajesh Kumar; Chaudhary, Sandeep

    2017-09-15

    This study reports the simultaneous delivery of EGFP siRNA and the chemotherapeutic drug, doxorubicin by means of the composition that results from the electrostatic interaction between positively charged siRNA-complexes of gold nanoparticles (AuNPs) capped with PEI, 25kDa (P25-AuNPs) and negatively charged carboxymethyl cellulose formulated PLGA nanoparticles loaded with doxorubicin. The nanoparticles and their facile interaction were studied by means of dynamic light scattering (DLS), zeta potential, transmission electron microscopic (TEM) measurements. The flow cytometric and confocal microscopic analysis evidenced the simultaneous internalization of both labelled siRNA and doxorubin into around 55% of the HeLa cancer cell population. Fluorescence microscopic studies enabled the visual analysis of EGFP expressing HeLa cells which suggested that the composition mediated codelivery resulted in a substantial downregulation of EGFP expression and intracellular accumulation of doxorubicin. Interestingly, codelivery treatment resulted in an increased cellular delivery of doxorubicin when compared to PLGA-DOX alone treatment. On the other hand, the activity of siRNA complexes of PEI-AuNPs was completely retained even when they were part of composition. The results suggest that this formulation can serve as promising tool for delivery applications in combinatorial anticancer therapy. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Programa de Enriquecimiento Instrumental (PEI: alternativa pedagógica que responde al desafío de calidad en educación

    Directory of Open Access Journals (Sweden)

    Aida Varela

    2006-01-01

    Full Text Available Este artículo presenta la implementación del Programa de Enriquecimento Instrumental en las Escuelas de Enseñanza Secundaria de la red pública estatal de bahia, experiencia acompañada por un proyecto de investigación delineado para evaluar la efectividad del programa como aplicación de la teoría de la modificabilidad cognitiva estructural. la metodología usada fue la experiencia de aprendizaje mediado, en lo que se refiere alproceso de asimilación, significación y transferencia /trascendencia de información por parte de profesores y alumnos. La investigación se ha constituido en un estudio comparativo entre alumnos de unidades escolares que ya integran el PEI a su currículo (grupo experimental y de aquellas que no tienen la investigación del PEI(grupo control. El análisis de los datos revela modificabilidad en el proceso enseñanza-aprendizaje.

  19. Impact of hydration on the micromechanical properties of the polymer composite structure of wood investigated with atomistic simulations

    Science.gov (United States)

    Kulasinski, Karol; Derome, Dominique; Carmeliet, Jan

    2017-06-01

    A model of the secondary layer of wood cell wall consisting of crystalline cellulose, hemicellulose, and lignin is constructed and investigated with molecular dynamics simulations in the full range of hydration: from dry to saturated state. The model is considered a composite with the cellulose fibrils embedded in hemicellulose and lignin, forming a soft amorphous matrix. Its complex structure leads to nonlinear and anisotropic swelling and mechanical weakening. The water diffusivity through the pores is affected by an interplay between stiff cellulose fibers and weakening amorphous polymers. The formation and breaking of hydrogen bonds within the polymers and at the interfaces is found to be the underlying mechanism of adsorption-induced mechanical softening. The model is tested for adsorption isotherm, mechanical moduli, hydrogen bonds, and water diffusivity that all undergo a substantial change as the hydration increases. The determined physical and mechanical properties, changing with hydration, agree qualitatively with experimental measurements.

  20. Inter- and intra-individual differences in skin hydration and surface lipids measured with mid-infrared spectroscopy

    Science.gov (United States)

    Ezerskaia, A.; Pereira, S. F.; Urbach, H. P.; Varghese, B.

    2016-03-01

    Skin health is characterized by heterogeneous system of water and lipids in upper layers providing protection from external environment and preventing loss of vital components of the body. Skin hydration (moisture) and sebum (skin surface lipids) are considered to be important factors in skin health; a right balance between these components is an indication of healthy skin and plays a central role in protecting and preserving skin integrity. In this manuscript we present inter- and intra-individual variation in skin hydration and surface lipids measured with a home-built experimental prototype based on infrared spectroscopy. Results show good agreement with measurements performed by commercially available instruments Corneometer and Sebumeter used for skin hydration and sebum measurements respectively.

  1. Geologic implications of gas hydrates in the offshore of India: results of the National Gas Hydrate Program Expedition 01

    Science.gov (United States)

    Collett, Timothy S.; Boswell, Ray; Cochran, J.R.; Kumar, Pushpendra; Lall, Malcolm; Mazumdar, Aninda; Ramana, Mangipudi Venkata; Ramprasad, Tammisetti; Riedel, Michael; Sain, Kalachand; Sathe, Arun Vasant; Vishwanath, Krishna

    2014-01-01

    The Indian National Gas Hydrate Program Expedition 01 (NGHP-01) is designed to study the occurrence of gas hydrate along the passive continental margin of the Indian Peninsula and in the Andaman convergent margin, with special emphasis on understanding the geologic and geochemical controls on the occurrence of gas hydrate in these two diverse settings. The NGHP-01 expedition established the presence of gas hydrates in the Krishna-Godavari and Mahanadi Basins, and the Andaman Sea. The expedition discovered in the Krishna-Godavari Basin one of the thickest gas hydrate accumulations ever documented, in the Andaman Sea one of the thickest and deepest gas hydrate stability zones in the world, and established the existence of a fully developed gas hydrate petroleum system in all three basins.

  2. Application of Cryogenic Infrared Spectra of Hydrated Chlorine Salts to Remote Sensing of Mars and Europa

    Science.gov (United States)

    Hanley, J.; Dalton, J. B.; Chevrier, V.; Jamieson, C. S.

    2012-12-01

    Chlorides and perchlorates have been measured on the surface of Mars by various landed missions (Viking, MER, Phoenix), but have eluded detection via remote sensing (e.g. MRO's CRISM). This is partly due to the featureless near-infrared spectra of Earth-relevant chlorides; however at Mars' temperatures, these salts would be hydrated and have characteristic features that may allow for their detection. In the case of Europa, Galileo's NIMS has revealed the surface to be mostly ice. The non-icy spectra have been compared to various hydrated minerals from spectral libraries, indicating that the non-ice material has a heavily hydrated salt component. However, a problem still exists in the lack of relevant spectra, especially at the low temperatures of Europa. In particular, chlorides are modeled as a possible component of the interior, and if the non-ice material is of an endogenic source, hydrated chlorides might be present on the surface. Oxidation of chlorides would result in chlorates (ClO3-) and/or perchlorates (ClO4-) as well. Both chlorates and perchlorates would lower the freezing point of water significantly (down to 205 K in the case of Mg(ClO4)2), adding new constraints to the arguments for a liquid layer below the surface. Using an environmental chamber to create the relevant temperatures, we have acquired new spectra of some of these hydrated salts, specifically MgCl2, Mg(ClO3)2, NaClO4 and Mg(ClO4)2, and will compare them to CRISM and NIMS data.

  3. Role of hydration on the functionality of a proteolytic enzyme α-chymotrypsin under crowded environment.

    Science.gov (United States)

    Verma, Pramod Kumar; Rakshit, Surajit; Mitra, Rajib Kumar; Pal, Samir Kumar

    2011-09-01

    Enzymes and other bio-macromolecules are not only sensitive to physical parameters such as pH, temperature and solute composition but also to water activity. A universally instructive way to vary water activity is the addition of osmotically active but otherwise inert solvents which also mimic the condition of an intercellular milieu. In the present contribution, the role of hydration on the functionality of a proteolytic enzyme α-chymotrypsin (CHT) is investigated by modulating the water activity with the addition of polyethylene glycols (PEG with an average molecular weight of 400). The addition of PEG increases the affinity of the enzyme to its substrate, however, followed by a decrease in the turnover number (k(cat)). Energetic calculations show that entrance path for the substrate is favoured, whereas the exit channel is restricted with increasing concentration of the crowding agent. This decrease is attributed to the thinning of the hydration shell of the enzyme due to the loss of critical water residues from the hydration surface of the enzyme as evidenced from volumetric and compressibility measurements. The overall secondary and tertiary structures of CHT determined from far-UV and near-UV circular dichroism (CD) measurements show no considerable change in the studied osmotic stress range. From kinetic and equilibrium data, we calculate 115 ± 30 numbers of water molecules to be altered during the enzymatic catalysis of CHT. Spectroscopic observation of water relaxation and rotational dynamics of ANS-CHT complex at various concentrations of the osmoting agent also support the dehydration of the hydration layer. Such dehydration/hydration processes during turnover imply a significant contribution of solvation to the energetics of the conformational changes.

  4. In-situ early-age hydration study of sulfobelite cements by synchrotron powder diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Álvarez-Pinazo, G.; Cuesta, A.; García-Maté, M.; Santacruz, I.; Losilla, E.R. [Departamento de Química Inorgánica, Universidad de Málaga, Campus Teatinos S/N., 29071 Málaga (Spain); Sanfélix, S.G. [Unidad Técnica de Investigación de Materiales, AIDICO, Avda. Benjamín Franklin, 17 Paterna, Valencia (Spain); Fauth, F. [CELLS-Alba synchrotron, Carretera BP 1413, Km. 3.3, E-08290 Cerdanyola, Barcelona (Spain); Aranda, M.A.G. [Departamento de Química Inorgánica, Universidad de Málaga, Campus Teatinos S/N., 29071 Málaga (Spain); CELLS-Alba synchrotron, Carretera BP 1413, Km. 3.3, E-08290 Cerdanyola, Barcelona (Spain); De la Torre, A.G., E-mail: mgd@uma.es [Departamento de Química Inorgánica, Universidad de Málaga, Campus Teatinos S/N., 29071 Málaga (Spain)

    2014-02-15

    Eco-friendly belite calcium sulfoaluminate (BCSA) cement hydration behavior is not yet well understood. Here, we report an in-situ synchrotron X-ray powder diffraction study for the first hours of hydration of BCSA cements. Rietveld quantitative phase analysis has been used to establish the degree of reaction (α). The hydration of a mixture of ye'elimite and gypsum revealed that ettringite formation (α ∼ 70% at 50 h) is limited by ye'elimite dissolution. Two laboratory-prepared BCSA cements were also studied: non-active-BCSA and active-BCSA cements, with β- and α′{sub H}-belite as main phases, respectively. Ye'elimite, in the non-active-BCSA system, dissolves at higher pace (α ∼ 25% at 1 h) than in the active-BCSA one (α ∼ 10% at 1 h), with differences in the crystallization of ettringite (α ∼ 30% and α ∼ 5%, respectively). This behavior has strongly affected subsequent belite and ferrite reactivities, yielding stratlingite and other layered phases in non-active-BCSA. The dissolution and crystallization processes are reported and discussed in detail. -- Highlights: •Belite calcium sulfoaluminate cements early hydration mechanism has been determined. •Belite hydration strongly depends on availability of aluminum hydroxide. •Orthorhombic ye’elimite dissolved at a higher pace than cubic one. •Ye’elimite larger reaction degree yields stratlingite formation by belite reaction. •Rietveld method quantified gypsum, anhydrite and bassanite dissolution rates.

  5. 葡萄糖淀粉酶在高压静电纺PEI/PVA纳米纤维膜上的离子吸附固定%Immobilization of Glucoamylase onto the Electrospinning PEI/PVA Composite Nanofiber Membrane via Ionic Adsorption

    Institute of Scientific and Technical Information of China (English)

    隋春红; 王程; 董顺福; 韩丽琴

    2015-01-01

    旨在应用离子结合法将葡萄糖淀粉酶固定在PEI/PVA纳米纤维膜上并对其理化性质进行研究。采用高压静电纺丝技术制备聚乙烯亚胺(PEI)/聚乙烯醇(PVA)纳米纤维膜,采用热交联方法使其具备水稳定性后,再利用离子吸附法固定葡萄糖淀粉酶。结果显示,利用红外光谱(FT-IR)表征固定有葡萄糖淀粉酶的PEI/PVA纳米纤维膜,表明葡萄糖淀粉酶可成功固定在静电纺丝形成的PEI/PVA纳米纤维膜表面。通过固定化葡萄糖淀粉酶的酶学性质鉴定,发现固定化葡萄糖淀粉酶的最适反应温度为65℃,比游离的葡萄糖淀粉酶提高了6℃;固定化葡萄糖淀粉酶的适用pH值范围明显变宽;热稳定性和存贮稳定性显著增强且可以重复使用。利用离子吸附法能简便地将蛋白质分子固定于纳米纤维膜上,具有一定的应用前景。%It was to study the physical and chemical properties of immobilization of glucoamylase on the PEI/PVA nanofibers via ion bonding. Polyethyleneimine(PEI)/polyvinyl alcohol(PVA)composite nanofiber membrane was prepared by electrospinning technology, and thermal crosslinking was applied to make it possess water stability. Glucoamylase was immobilized onto the electrospinning PEI/PVA composite nanofiber membrane via ion adsorption. Results showed that fourier transform infrared spectrum(FT-IR)indicated that glucoamylase can be successfully fixed on the surface of the electrospinning PEI/PVA composite nanofiber membrane. Then, the enzymatic properties of immobilized glucoamylase were identified. The results have shown that the optimum reaction temperature of immobilized glucoamylase is 65℃, 6 degrees higher than free glucoamylase, and the applicable pH range of immobilized glucoamylase is wider than free glucoamylase significantly. In addition, immobilized glucoamylase also has good thermal stability, storage stability and reusability. The use of ion

  6. Mechanical behavior of a composite interface: Calcium-silicate-hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Palkovic, Steven D.; Moeini, Sina; Büyüköztürk, Oral, E-mail: obuyuk@mit.edu [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Yip, Sidney [Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-07-21

    The generalized stacking fault (GSF) is a conceptual procedure historically used to assess shear behavior of defect-free crystalline structures through molecular dynamics or density functional theory simulations. We apply the GSF technique to the spatially and chemically complex quasi-layered structure of calcium-silicate-hydrates (C-S-H), the fundamental nanoscale binder within cementitious materials. A failure plane is enforced to calculate the shear traction-displacement response along a composite interface containing highly confined water molecules, hydroxyl groups, and calcium ions. GSF simulations are compared with affine (homogeneous) shear simulations, which allow strain to localize naturally in response to the local atomic environment. Comparison of strength and deformation behavior for the two loading methods shows the composite interface controls bulk shear deformation. Both models indicate the maximum shear strength of C-S-H exhibits a normal-stress dependency typical of cohesive-frictional materials. These findings suggest the applicability of GSF techniques to inhomogeneous structures and bonding environments, including other layered systems such as biological materials containing organic and inorganic interfaces.

  7. Origin and character of gaseous hydrocarbons in the hydrate and non-hydrate charged sediments on the Norway - Svalbard margins

    Energy Technology Data Exchange (ETDEWEB)

    Vaular, Espen Nesheim

    2011-05-15

    Gas incubated in clathrate water-structures, stabilizes the hydrogen bonded substance termed gas hydrate. In the marine environment vast amount of carbon is stored as gas hydrates within the temperature and pressure zone these ice-like structures are stable. Natural gas hydrate mapping and characterization is important basic research that brings about critical knowledge concerning various topics. Natural gas hydrates is a vital part of the carbon cycle, it is a potential energy resource (and thereby a potential climate agent) and it is a potential geo-hazard. One of the goals the GANS initiative aimed at exploring, was the hydrate bearing sediment of the Norway -Svalbard margins, to investigate the character and expansion of natural gas hydrates. Part of the investigation was to define how the gas in the hydrated sediment was produced and where it came from. As a result this thesis addresses the matter of light hydrocarbon characterization and origin in two Norwegian hydrate deposits. On cruises to Vestnesa on the Svalbard margin and to Nyegga in the mid-Norwegian margin, samples of hydrate charged and non-hydrate charged sediments were obtained and analyzed. Through compositional and isotopic analyses the origin of the hydrate bound gas in the fluid escape feature G11 at Nyegga was determined. The hydrate incubated methane is microbial produced as well as parts of the hydrate bound ethane. The compositional analysis in both the Nyegga area and at the Vestnesa Ridge points at thermogenic contributions in the sediment interstitials and pore water. The two hydrate bearing margins show large differences in hydrocarbon content and microbial activity in the pockmarks investigated. The gravity cores from the penetrated pockmark at Vestnesa showed low hydrocarbon content and thus suggest ceased or periodic venting. The fluid flow escape features at Nyegga show large variety of flux rates based on ROV monitoring and headspace analysis of the sediment and pore water. The

  8. A statistical mechanical description of biomolecular hydration

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-02-01

    We present an efficient and accurate theoretical description of the structural hydration of biological macromolecules. The hydration of molecules of almost arbitrary size (tRNA, antibody-antigen complexes, photosynthetic reaction centre) can be studied in solution and in the crystal environment. The biomolecular structure obtained from x-ray crystallography, NMR, or modeling is required as input information. The structural arrangement of water molecules near a biomolecular surface is represented by the local water density analogous to the corresponding electron density in an x-ray diffraction experiment. The water-density distribution is approximated in terms of two- and three-particle correlation functions of solute atoms with water using a potentials-of-mean-force expansion.

  9. Experimental techniques for cement hydration studies

    Directory of Open Access Journals (Sweden)

    Andreas Luttge

    2011-10-01

    Full Text Available Cement hydration kinetics is a complex problem of dissolution, nucleation and growth that is still not well understood, particularly in a quantitative way. While cement systems are unique in certain aspects they are also comparable to natural mineral systems. Therefore, geochemistry and particularly the study of mineral dissolution and growth may be able to provide insight and methods that can be utilized in cement hydration research. Here, we review mainly what is not known or what is currently used and applied in a problematic way. Examples are the typical Avrami approach, the application of Transition State Theory (TST to overall reaction kinetics and the problem of reactive surface area. Finally, we suggest an integrated approach that combines vertical scanning interferometry (VSI with other sophisticated analytical techniques such as atomic force microscopy (AFM and theoretical model calculations based on a stochastic treatment.

  10. Predicting hydration energies for multivalent ions

    DEFF Research Database (Denmark)

    Andersson, Martin Peter; Stipp, Susan Louise Svane

    2014-01-01

    (TZVP) level. Agreement with experimental data for monovalent and divalent ions is good and shows no significant systematic errors. Predictions are noticeably better than with standard COSMO. The agreement with experimental data for trivalent and tetravalent ions is slightly worse and shows systematic...... errors. Our results indicate that quantum chemical calculations combined with COSMO-RS solvent treatment is a reliable method for treating multivalent ions in solution, provided one hydration shell of explicit water molecules is included for metal cations. The accuracy is not high enough to allow...... absolute predictions of hydration energies but could be used to investigate trends for several ions, thanks to the low computational cost, in particular for ligand exchange reactions....

  11. Obsidian hydration dating of volcanic events

    Science.gov (United States)

    Friedman, I.; Obradovich, J.

    1981-01-01

    Obsidian hydration dating of volcanic events had been compared with ages of the same events determined by the 14C and KAr methods at several localities. The localities, ranging in age from 1200 to over 1 million yr, include Newberry Craters, Oregon; Coso Hot Springs, California; Salton Sea, California; Yellowstone National Park, Wyoming; and Mineral Range, Utah. In most cases the agreement is quite good. A number of factors including volcanic glass composition and exposuretemperature history must be known in order to relate hydration thickness to age. The effect of composition can be determined from chemical analysis or the refractive index of the glass. Exposure-temperature history requires a number of considerations enumerated in this paper. ?? 1981.

  12. Methane hydrates and contemporary climate change

    Science.gov (United States)

    Ruppel, Carolyn D.

    2011-01-01

    As the evidence for warming climate became better established in the latter part of the 20th century (IPCC 2001), some scientists raised the alarm that large quantities of methane (CH4) might be liberated by widespread destabilization of climate-sensitive gas hydrate deposits trapped in marine and permafrost-associated sediments (Bohannon 2008, Krey et al. 2009, Mascarelli 2009). Even if only a fraction of the liberated CH4 were to reach the atmosphere, the potency of CH4 as a greenhouse gas (GHG) and the persistence of its oxidative product (CO2) heightened concerns that gas hydrate dissociation could represent a slow tipping point (Archer et al. 2009) for Earth's contemporary period of climate change.

  13. Propane hydrate nucleation: Experimental investigation and correlation

    DEFF Research Database (Denmark)

    Jensen, Lars; Thomsen, Kaj; von Solms, Nicolas

    2008-01-01

    In this work the nucleation kinetics of propane gas hydrate has been investigated experimentally using a stirred batch reactor. The experiments have been performed isothermally recording the pressure as a function of time. Experiments were conducted at different stirring rates, but in the same......) to the aqueous phase was found to reduce the gas dissolution rate slightly. However the induction times were prolonged quite substantially upon addition of PVP.The induction time data were correlated using a newly developed induction time model based on crystallization theory also capable of taking into account...... the presence of additives. In most cases reasonable agreement between the data and the model could be obtained. The results revealed that especially the effective surface energy between propane hydrate and water is likely to change when the stirring rate varies from very high to low. The prolongation...

  14. Numerical investigations of the fluid flows at deep oceanic and arctic permafrost-associated gas hydrate deposits

    Science.gov (United States)

    Frederick, Jennifer Mary

    Methane hydrate is an ice-like solid which sequesters large quantities of methane gas within its crystal structure. The source of methane is typically derived from organic matter broken down by thermogenic or biogenic activity. Methane hydrate (or more simply, hydrate) is found around the globe within marine sediments along most continental margins where thermodynamic conditions and methane gas (in excess of local solubility) permit its formation. Hydrate deposits are quite possibly the largest reservoir of fossil fuel on Earth, however, their formation and evolution in response to changing thermodynamic conditions, such as global warming, are poorly understood. Upward fluid flow (relative to the seafloor) is thought to be important for the formation of methane hydrate deposits, which are typically found beneath topographic features on the seafloor. However, one-dimensional models predict downward flow relative to the seafloor in compacting marine sediments. The presence of upward flow in a passive margin setting can be explained by fluid focusing beneath topography when sediments have anisotropic permeability due to sediment bedding layers. Even small slopes (10 degrees) in bedding planes produce upward fluid velocity, with focusing becoming more effective as slopes increase. Additionally, focusing causes high excess pore pressure to develop below topographic highs, promoting high-angle fracturing at the ridge axis. Magnitudes of upward pore fluid velocity are much larger in fractured zones, particularly when the surrounding sediment matrix is anisotropic in permeability. Enhanced flow of methane-bearing fluids from depth provides a simple explanation for preferential accumulation of hydrate under topographic highs. Models of fluid flow at large hydrate provinces can be constrained by measurements of naturally-occurring radioactive tracers. Concentrations of cosmogenic iodine, 129-I, in the pore fluid of marine sediments often indicate that the pore fluid is much

  15. Investigation of the effects caused by applying voltage in Layer-by-Layer self-assembly method

    Directory of Open Access Journals (Sweden)

    Omura Y.

    2013-08-01

    Full Text Available Recently, Layer-by-Layer (LbL self-assembly method under applied voltage (voltage-applied LbL attracts great attention. It is reported that the method enables more abundant film adsorption than conventional LbL method. However, a small proportion of experimental results about adsorption of polyelectrolytes by voltage-applied LbL have been reported. In this study, voltage-applied LbL method using weakly charged polyelectrolytes was examined. Poly (allylamine hydrochloride (PAH and Poly (ethylene imine (PEI as cationic solutions and Poly (acrylic acid (PAA as anionic solution were chosen. The pH of solutions was adjusted to several conditions and film of PAH/PAA and film of PEI/PAA were fabricated by voltage-applied LbL method. Change of adsorption behavior and film morphology by applying voltage depended on pH condition of solutions. When pH of PAH/PAA solutions was 3.9/3.8, respectively, the film adsorption was accelerated by applying voltage. Moreover, in this condition, the surface morphology remarkably changes and texture structure appears by applying voltage. Consequently, it was found that applying voltage in LbL method was effective in controlling film adsorption and the surface nano structure.

  16. Superior thermoelectric response in the 3R phases of hydrated Na x RhO 2

    KAUST Repository

    Saeed, Y.

    2014-03-17

    Density functional theory is used to investigate the thermoelectric properties of the 3R phases of NaxRhO2 for different Na vacancy configurations and concentrations. As compared to the analogous 2H phases, the modified stacking of the atomic layers in the 3R phases reduces the interlayer coupling. As a consequence, the 3R phases are found to be superior in the technologically relevant temperature range. The Rh d3z2-r2 orbitals still govern the valence band maxima and therefore determine the transport properties. A high figure of merit of 0.35 is achieved in hydrated Na0.83RhO2 at 580 K by water intercalation, which is 34% higher than in the non-hydrated phase.

  17. Removal of methyl orange from aqueous solutions through adsorption by calcium aluminate hydrates.

    Science.gov (United States)

    Zhang, Ping; Wang, Tianqi; Qian, Guangren; Wu, Daishe; Frost, Ray L

    2014-07-15

    Methyl orange (MO) is a kind of anionic dye and widely used in industry. In this study, tricalcium aluminate hydrates (Ca-Al-LDHs) are used as an adsorbent to remove methyl orange (MO) from aqueous solutions. The resulting products were studied by X-ray diffraction (XRD), infrared spectroscopy (MIR), thermal analysis (TG-DTA) and scanning electron microscope (SEM). The XRD results indicated that the MO molecules were successfully intercalated into the tricalcium aluminate hydrates, with the basal spacing of Ca-Al-LDH expanding to 2.48 nm. The MIR spectrum for CaAl-MO-LDH shows obvious bands assigned to the N=N, N=H stretching vibrations and S=O, SO3(-) group respectively, which are considered as marks to assess MO(-) ion intercalation into the interlayers of LDH. The overall morphology of CaAl-MO-LDH displayed a "honey-comb" like structure, with the adjacent layers expanded.

  18. A Proposed Unified Theory of Hydrated Asteroids

    Science.gov (United States)

    Rivkin, Andrew S.

    2016-10-01

    The last decade has seen tremendous growth in the study of hydrated and hydroxylated minerals (hereafter simply called "hydrated minerals") on asteroids. Several workers have used absorptions in the 3-µm region and a correlated absorption near 0.7 µm to determine not only the presence or absence of these minerals but gain insight into the compositions of asteroid surfaces. Spectra of hundreds of asteroids have been measured and published or presented at meetings, and we are in a position to use these newer datasets to globally assess the patterns and relationships we see, as previously done by Jones et al. (1990) and Takir et al. (2012). There are several points to be addressed by any such assessment. Several different band shapes are seen in the 3-µm region, only one of which is seen in the hydrated meteorites in our collections. However, each of the main 3-µm band shapes is represented among parent bodies of collisional families. There seems to be little correlation in general between asteroid spectral class and 3-µm band shape, save for the Ch meteorites which are overwhelmingly likely to share the same band shape as the CM meteorites. Ceres has an unusual but not unique band shape, which has thus far only been found on the largest asteroids. I will present an outline scenario for the formation and evolution of hydrated asteroids, where aqueous alteration serves to lithify some objects while other objects remain unlithified and still others differentiate and suffer collisional modification. While some details will no doubt be altered to account for better or new information, this scenario is offered as a starting point for discussion.

  19. Bioimpedance in medicine: Measuring hydration influence

    Science.gov (United States)

    Hlubik, J.; Hlubik, P.; Lhotska, L.

    2010-04-01

    The aim of the paper is to present results of our ongoing research focused on the influence of body hydration on the body impedance measurements and also on the influence of the frequency used for the measurement. The question is why to measure human body composition and if these values have beneficial results. First goal of the work deals with a question of measuring human body composition. The performed measurements showed certain influence which must be verified by repeated experiments.

  20. Methane storage in dry water gas hydrates.

    Science.gov (United States)

    Wang, Weixing; Bray, Christopher L; Adams, Dave J; Cooper, Andrew I

    2008-09-03

    Dry water stores 175 v(STP)/v methane at 2.7 MPa and 273.2 K in a hydrate form which is close to the Department of Energy volumetric target for methane storage. Dry water is a silica-stabilized free-flowing powder (95% wt water), and fast methane uptakes were observed (90% saturation uptake in 160 min with no mixing) as a result of the relatively large surface-to-volume ratio of this material.

  1. Effect of Gemini-type surfactant on methane hydrate formation

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, K.E.; Park, J.M.; Kim, C.U.; Chae, H.J.; Jeong, S.Y. [Korea Research Inst. of Chemical Technology, Jang-Dong, Yuseong-Gu, Daejeon (Korea, Republic of)

    2008-07-01

    Natural gas hydrates are formed from water and natural gas molecules at particular temperatures and pressures that become ice-like inclusion compounds. Gas hydrates offer several benefits such as energy resource potential and high storage capacity of natural gas in the form of hydrates. However, the application of natural gas hydrates has been deterred by its low formation rate and low conversion ratio of water into hydrate resulting in low actual storage capacity. This paper presented an experimental study to determine the effect of adding a novel Gemini-type surfactant on methane hydrate formation. The experimental study was described with reference to the properties of prepared diols and properties of prepared disulfonates. Gemini surfactant is the family of surfactant molecules possessing more than one hydrophobic tail and hydrophilic head group. They generally have better surface-active properties than conventional surfactants of equal chain length. The paper presented the results of the study in terms of the reactions of diols with propane sultone; storage capacity of hydrate formed with and without surfactant; and methane hydrate formation with and without disulfonate. It was concluded that the methane hydrate formation was accelerated by the addition of novel anionic Gemini-type surfactants and that hydrate formation was influenced by the surfactant concentration and alkyl chain length. For a given concentration, the surfactant with the highest chain length demonstrated the highest formation rate and storage capacity. 5 refs., 3 tabs., 4 figs.

  2. Hydration process in Portland cement blended with activated coal gangue

    Institute of Scientific and Technical Information of China (English)

    Xian-ping LIU; Pei-ming WANG; Min-ju DING

    2011-01-01

    This paper deals with the hydration of a blend of Portland cement and activated coal gangue in order to determine the relationship between the degree of hydration and compressive strength development.The hydration process was investigated by various means:isothermal calorimetry,thermal analysis,non-cvaporable water measurement,and X-ray diffraction analysis.The results show that the activated coal gangue is a pozzolanic material that contributes to the hydration of the cement blend.The pozzolanic reaction occurs over a period of between 7 and 90 d,consuming portlandite and forming both crystal hydrates and ill-crystallized calcium silicate hydrates.These hydrates are similar to those found in pure Portland cement.The results show that if activated coal gangue is substituted for cement at up to 30% (w/w),it does not significantly affect the final compressive strength of the blend.A long-term compressive strength improvement can in fact be achieved by using activated coal gangue as a supplementary cementing material.The relationship between compressive strength and degree of hydration for both pure Portland cement and blended cement can be described with the same equation.However,the parameters are different since blended cement produces fewer calcium silicate hydrates than pure Portland cement at the same degree of hydration.

  3. Gas Hydrate Growth Kinetics: A Parametric Study

    Directory of Open Access Journals (Sweden)

    Remi-Erempagamo Tariyemienyo Meindinyo

    2016-12-01

    Full Text Available Gas hydrate growth kinetics was studied at a pressure of 90 bars to investigate the effect of temperature, initial water content, stirring rate, and reactor size in stirred semi-batch autoclave reactors. The mixing energy during hydrate growth was estimated by logging the power consumed. The theoretical model by Garcia-Ochoa and Gomez for estimation of the mass transfer parameters in stirred tanks has been used to evaluate the dispersion parameters of the system. The mean bubble size, impeller power input per unit volume, and impeller Reynold’s number/tip velocity were used for analyzing observed trends from the gas hydrate growth data. The growth behavior was analyzed based on the gas consumption and the growth rate per unit initial water content. The results showed that the growth rate strongly depended on the flow pattern in the cell, the gas-liquid mass transfer characteristics, and the mixing efficiency from stirring. Scale-up effects indicate that maintaining the growth rate per unit volume of reactants upon scale-up with geometric similarity does not depend only on gas dispersion in the liquid phase but may rather be a function of the specific thermal conductance, and heat and mass transfer limitations created by the limit to the degree of the liquid phase dispersion is batched and semi-batched stirred tank reactors.

  4. Intermolecular Hydrogen Transfer in Isobutane Hydrate

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    Takeshi Sugahara

    2012-05-01

    Full Text Available Electron spin resonance (ESR spectra of butyl radicals induced with γ-ray irradiation in the simple isobutane (2-methylpropane hydrate (prepared with deuterated water were investigated. Isothermal annealing results of the γ-ray-irradiated isobutane hydrate reveal that the isobutyl radical in a large cage withdraws a hydrogen atom from the isobutane molecule through shared hexagonal-faces of adjacent large cages. During this “hydrogen picking” process, the isobutyl radical is apparently transformed into a tert-butyl radical, while the sum of isobutyl and tert-butyl radicals remains constant. The apparent transformation from isobutyl to tert-butyl radicals is an irreversible first-order reaction and the activation energy was estimated to be 35 ± 3 kJ/mol, which was in agreement with the activation energy (39 ± 5 kJ/mol of hydrogen picking in the γ-ray-irradiated propane hydrate with deuterated water.

  5. The interaction of climate change and methane hydrates

    Science.gov (United States)

    Ruppel, Carolyn D.; Kessler, John D.

    2017-01-01

    Gas hydrate, a frozen, naturally-occurring, and highly-concentrated form of methane, sequesters significant carbon in the global system and is stable only over a range of low-temperature and moderate-pressure conditions. Gas hydrate is widespread in the sediments of marine continental margins and permafrost areas, locations where ocean and atmospheric warming may perturb the hydrate stability field and lead to release of the sequestered methane into the overlying sediments and soils. Methane and methane-derived carbon that escape from sediments and soils and reach the atmosphere could exacerbate greenhouse warming. The synergy between warming climate and gas hydrate dissociation feeds a popular perception that global warming could drive catastrophic methane releases from the contemporary gas hydrate reservoir. Appropriate evaluation of the two sides of the climate-methane hydrate synergy requires assessing direct and indirect observational data related to gas hydrate dissociation phenomena and numerical models that track the interaction of gas hydrates/methane with the ocean and/or atmosphere. Methane hydrate is likely undergoing dissociation now on global upper continental slopes and on continental shelves that ring the Arctic Ocean. Many factors—the depth of the gas hydrates in sediments, strong sediment and water column sinks, and the inability of bubbles emitted at the seafloor to deliver methane to the sea-air interface in most cases—mitigate the impact of gas hydrate dissociation on atmospheric greenhouse gas concentrations though. There is no conclusive proof that hydrate-derived methane is reaching the atmosphere now, but more observational data and improved numerical models will better characterize the climate-hydrate synergy in the future.

  6. Molecular and Isotopic Composition of Volatiles in Gas Hydrates and in Sediment from the Joetsu Basin, Eastern Margin of the Japan Sea

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    Akihiro Hachikubo

    2015-05-01

    Full Text Available Hydrate-bearing sediment cores were retrieved from the Joetsu Basin (off Joetsu city, Niigata Prefecture at the eastern margin of the Japan Sea during the MD179 gas hydrates cruise onboard R/V Marion Dufresne in June 2010. We measured molecular and stable isotope compositions of volatiles bound in the gas hydrates and headspace gases obtained from sediments to clarify how the minor components of hydrocarbons affects to gas hydrate crystals. The hydrate-bound hydrocarbons at Umitaka Spur (southwestern Joetsu Basin primarily consisted of thermogenic methane, whereas those at Joetsu Knoll (northwestern Joetsu Basin, about 15 km from Umitaka Spur contained both thermogenic methane and a mixture of thermogenic and microbial methane. The depth concentration profiles of methane, ethane, propane, CO2, and H2S in the sediments from the Joetsu Basin area showed shallow sulfate–methane interface (SMI and high microbial methane production beneath the SMI depth. Relatively high concentrations of propane and neopentane (2,2-dimethylpropane were detected in the headspace gases of the hydrate-bearing sediment cores obtained at Umitaka Spur and Joetsu Knoll. Propane and neopentane cannot be encaged in the structure I hydrate; therefore, they were probably excluded from the hydrate crystals during the structure I formation process and thus remained in the sediment and/or released from the small amounts of structure II hydrate that can host such large gas molecules. The lower concentrations of ethane and propane in the sediment, high δ13C of propane and isobutane, and below-detection normal butane and normal pentane at Umitaka Spur and Joetsu Knoll suggest biodegradation in the sediment layers.

  7. Assessing fluid-gas expulsion geology and gas hydrate deposits across the Gulf of Mexico with multicomponent and multifrequency seismic data

    Energy Technology Data Exchange (ETDEWEB)

    Hardage, B.A.; Sava, D.C.; Murray, P.E.; DeAngelo, M.V.; Backus, M.M.; Graebner, R.J. [Texas Univ., Austin, TX (United States). Bureau of Economic Geology; Roberts, H.H. [Louisiana State Univ., Baton Rouge, LA (United States). Coastal Studies Inst.

    2008-07-01

    This paper reported on a study of 2 fluid-gas expulsion sites across a portion of the Green Canyon area of the Gulf of Mexico, where deep-water fields and oil and gas seeps are numerous. Hydrates are pervasive across the 2 expulsion sites studied at Typhoon and Genesis Fields. The 2 sites GD 237 and GC 204 are positioned on the flank of an intraslope basin containing a thick sedimentary sequence. Major fluid-gas migration pathways occur near the edges of shallow subsurface salt masses. The two-fluid gas expulsion sites were investigated with 4-component ocean-bottom-cable (4C OBC) seismic data and chirp-sonar data acquired by an autonomous underwater vehicle (AUV). The study examined the near-seafloor geology of the deep-water, fluid-gas expulsion features to estimate hydrate concentrations in strata spanned by the hydrate stability zone local to these expulsion sites. In some units, hydrate concentrations were more than 30 per cent of the available pore space of the host sediment. A free-gas layer was discovered immediately under the base of the hydrate stability zone across each expulsion site area. It was revealed by a reduction in V{sub p} velocity. Although the amount of free-gas in this zone has not been estimated, it is expected that the zone has a gas saturation of only a few percentage points. This free-gas zone was not obviously different from hydrate-bearing zones when examining resistivity logs. It was concluded that interpreting the thickness of a hydrate stability zone from resistivity logs alone could result in an overestimation of the thickness of the hydrate stability zone and the amount of hydrate that exists near deep-water expulsion features. 10 refs., 13 figs.

  8. Driving force for the hydration of the swelling clays: case of montmorillonites saturated with alkaline-earth cations.

    Science.gov (United States)

    Salles, Fabrice; Douillard, Jean-Marc; Bildstein, Olivier; Gaudin, Cedric; Prelot, Benedicte; Zajac, Jerzy; Van Damme, Henri

    2013-04-01

    Important structural modifications occur in swelling clays upon water adsorption. The multi-scale evolution of the swelling clay structure is usually evidenced by various experimental techniques. However, the driving fo