WorldWideScience

Sample records for adsorbed explosive molecules

  1. Micro-differential thermal analysis detection of adsorbed explosive molecules using microfabricated bridges

    DEFF Research Database (Denmark)

    Senesac, Larry R.; Yi, Dechang; Greve, Anders;

    2009-01-01

    heating rate, produces unique and reproducible thermal response patterns within 50 ms that are characteristic to classes of adsorbed explosive molecules. We demonstrate that this micro-differential thermal analysis technique can selectively detect explosives, providing a method for fast direct detection...... layers that rely on weak chemical interactions provides only partial selectivity. Here we show that the very low thermal mass of micromechanical sensors can be used to produce unique responses that can be used for achieving chemical selectivity without losing sensitivity or reversibility. We demonstrate...

  2. Detection of adsorbed explosive molecules using thermal response of suspended microfabricated bridges

    DEFF Research Database (Denmark)

    Yi, Dechang; Greve, Anders; Hales, Jan Harry;

    2008-01-01

    Here we present a thermophysical technique that is capable of differentiating vapor phase adsorbed explosives from nonexplosives and is additionally capable of differentiating individual species of common explosive vapors. This technique utilizes pairs of suspended microfabricated silicon bridges...... that can be heated in a controlled fashion. The differential thermal response of the bridges with and without adsorbed explosive vapor shows unique and reproducible characteristics depending on the nature of the adsorbed explosives. The tunable heating rate method described here is capable of providing...... unique signals for subnanogram quantities of adsorbed explosives within 50 ms. (C) 2008 American Institute of Physics....

  3. Hydrophobic Porous Material Adsorbs Small Organic Molecules

    Science.gov (United States)

    Sharma, Pramod K.; Hickey, Gregory S.

    1994-01-01

    Composite molecular-sieve material has pore structure designed specifically for preferential adsorption of organic molecules for sizes ranging from 3 to 6 angstrom. Design based on principle that contaminant molecules become strongly bound to surface of adsorbent when size of contaminant molecules is nearly same as that of pores in adsorbent. Material used to remove small organic contaminant molecules from vacuum systems or from enclosed gaseous environments like closed-loop life-support systems.

  4. Size selective hydrophobic adsorbent for organic molecules

    Science.gov (United States)

    Sharma, Pramod K. (Inventor); Hickey, Gregory S. (Inventor)

    1997-01-01

    The present invention relates to an adsorbent formed by the pyrolysis of a hydrophobic silica with a pore size greater than 5 .ANG., such as SILICALITE.TM., with a molecular sieving polymer precursor such as polyfurfuryl alcohol, polyacrylonitrile, polyvinylidene chloride, phenol-formaldehyde resin, polyvinylidene difluoride and mixtures thereof. Polyfurfuryl alcohol is the most preferred. The adsorbent produced by the pyrolysis has a silicon to carbon mole ratio of between about 10:1 and 1:3, and preferably about 2:1 to 1:2, most preferably 1:1. The pyrolysis is performed as a ramped temperature program between about 100.degree. and 800.degree. C., and preferably between about 100.degree. and 600.degree. C. The present invention also relates to a method for selectively adsorbing organic molecules having a molecular size (mean molecular diameter) of between about 3 and 6 .ANG. comprising contacting a vapor containing the small organic molecules to be adsorbed with the adsorbent composition of the present invention.

  5. Dynamic scanning probe microscopy of adsorbed molecules on graphite

    OpenAIRE

    Berdunov, N.; Pollard, A J; Beton, P. H.

    2008-01-01

    We have used a combined dynamic scanning tunneling and atomic force microscope to study the organisation of weakly bound adsorbed molecules on a graphite substrate. Specifically we have acquired images of islands of the perylene derivative molecules. These weakly bound molecules may be imaged in dynamic STM, in which the probe is oscillated above the surface. We show that molecular resolution may be readily attained and that a similar mode of imaging may be realised using conventional STM arr...

  6. Adsorbed molecules in external fields: Effect of confining potential.

    Science.gov (United States)

    Tyagi, Ashish; Silotia, Poonam; Maan, Anjali; Prasad, Vinod

    2016-12-01

    We study the rotational excitation of a molecule adsorbed on a surface. As is well known the interaction potential between the surface and the molecule can be modeled in number of ways, depending on the molecular structure and the geometry under which the molecule is being adsorbed by the surface. We explore the effect of change of confining potential on the excitation, which is largely controlled by the static electric fields and continuous wave laser fields. We focus on dipolar molecules and hence we restrict ourselves to the first order interaction in field-molecule interaction potential either through permanent dipole moment or/and the molecular polarizability parameter. It is shown that confining potential shapes, strength of the confinement, strongly affect the excitation. We compare our results for different confining potentials. PMID:27387127

  7. Hydrogen molecule on lithium adsorbed graphene: A DFT study

    Science.gov (United States)

    Kaur, Gagandeep; Gupta, Shuchi; Gaganpreet, Dharamvir, Keya

    2016-05-01

    Electronic structure calculations for the adsorption of molecular hydrogen on lithium (Li) decorated and pristine graphene have been studied systematically using SIESTA code [1] within the framework of the first-principle DFT under the Perdew-Burke-Ernzerhof (PBE) form of the generalized gradient approximation (GGA)[2], including spin polarization. The energy of adsorption of hydrogen molecule on graphene is always enhanced by the presence of co-adsorbed lithium. The most efficient adsorption configuration is when H2 is lying parallel to lithium adsorbed graphene which is in contrast to its adsorption on pristine graphene (PG) where it prefers perpendicular orientation.

  8. Dynamics of different molecules adsorbed in porous media

    Indian Academy of Sciences (India)

    S Mitra; V S Kamble; A K Tripathi; N M Gupta; R Mukhopadhyay

    2004-08-01

    We present in this paper a comparative study on the dynamics of benzene, cyclohexane, and methanol molecules, confined in the pores of MCM-41 molecular sieve and HZSM-5 zeolite. The quasi-elastic neutron scattering (QENS) measurements revealed that the physical state of these adsorbed molecules depended not only on the structural characteristics of the host matrix but also on the chemical properties, such as dipole moment, of the guest molecules. Thus, while no motion was observed in the time-scale of 10−10 –10−12 s in the case of methanol, the larger size benzene and cyclohexane molecules are found to perform six-fold and three-fold jump rotation, respectively, when adsorbed inside the cages of HZSM-5 at room temperature. At the same time, all the three molecules are found to undergo a translational motion inside the pores of MCM-41 molecular sieves, the value of diffusion constant being the lowest in case of methanol because of its higher polarity. Translationl motion of the guest molecules inside the pores of MCM-41 can be satisfactorily described by Chudley–Eliott fixed jump length diffusion and accordingly the residence time, jump length and diffusion constant are estimated.

  9. Detection of Ordered Molecules Adsorbed on Graphene: a Theoretical Study

    Science.gov (United States)

    Wang, Yong; Zhang, Xue-Qing; Li, Hui

    2014-11-01

    Graphene has been demonstrated to be able to detect individual gas molecules [Schedin et al. Nat. Mater. 6 (2007) 652], which has attracted a lot of sensor research activities. Here we report for the first time that graphene is capable of detecting the ordering degree of absorbed water molecules. The efficiency of doping varies from the degrees of molecular ordering. The simulated results show that the highly ordered water molecules contribute more to the doping effect, which reduces the conductance of the water/graphene system.

  10. Auger electron spectroscopy as a tool for measuring intramolecular charges of adsorbed molecules

    Science.gov (United States)

    Magkoev, T. T.

    1993-10-01

    A way for the determination of the values of intramolecular charges of adsorbed molecules of some binary dielectrics, based on Auger electron spectroscopy (AES), is proposed. These values can be obtained from the coverage dependences of the ratios of intensities of anion KL 23L 23 and KL 1L 1 Auger transitions, which are sensitive to the amount of charge at the 2p-orbitals. As an example, MgO adsorbed on Mo(110) is presented.

  11. LACTOFERRIN ADSORBED ONTO BIOMIMETIC HYDROXYAPATITE: A MULTIFUNCTIONAL ANTIMICROBIAL MOLECULE

    OpenAIRE

    Fulgione, Andrea

    2015-01-01

    Lactoferrin (LF), is an iron-binding protein, belonging to transferrin family. It is found in the mucosal secretions (tears, saliva, milk, and colostrums) of the majority of mammalian species, including humans. LF is a multitask molecule: it partecipates to iron absorption and distribution, but also displays anti-inflammatory, antioxidant, anticarcinogenic, and antimicrobial properties. Hydroxyapatite (HA) plays an important role in the formation of the bony skeleton and bone remodeling. A...

  12. Local field distribution and configuration of CO molecules adsorbed on the nanostructure platinum surface

    Institute of Scientific and Technical Information of China (English)

    Huang Xiao-Jing; He Su-Zhen; Wu Chen-Xu

    2006-01-01

    This paper shows that the local electric field distribution near the nanostructure metallic surface is obtained by solving the Laplace equation, and furthermore, the configuration of CO molecules adsorbed on a Pt nanoparticle surface is obtained by using Monte Carlo simulation. It is found that the uneven local electric field distribution induced by the nanostructure surface can influence the configuration of carbon monoxide (CO) molecules by a force, which drags the adsorbates to the poles of the nanoparticles. This result, together with our results obtained before, may explain the experimental results that the nanostructure metallic surface can lead to abnormal phenomena such as anti-absorption infrared effects.

  13. Local electric field and configuration of CO molecules adsorbed on a nanostructured surface with nanocones

    Institute of Scientific and Technical Information of China (English)

    You Rong-Yi; Huang Xiao-Jing

    2009-01-01

    Based on the nanostructured surface model that the (platinum,Pt) nanocones grow out symmetrically from a plane substrate,the local electric field near the conical nanoparticle surface is computed and discussed. On the basis of these results,the adsorbed CO molecules are modelled as dipoles,and three kinds of interactions,I.e. Interactions between dipoles and local electric field,between dipoles and dipoles,as well as between dipoles and nanostructured substrate,are taken into account. The spatial configuration of CO molecules adsorbed on the nanocone surface is then given by Monte-Carlo simulation. Our results show that the CO molecules adsorbed on the nanocone surface cause local agglomeration under the action of an external electric field,and this agglomeration becomes more compact with decreasing conical angle,which results in a stronger interaction among molecules. These results serve as a basis for explaining abnormal phenomena such as the abnormal infrared effect (AIRE),which was found when CO molecules were adsorbed on the nancetructured transition-metal surface.

  14. Spectroscopic observations of the displacement dynamics of physically adsorbed molecules-CO on C60

    Science.gov (United States)

    Yuan, Chunqing; Yates, John T.

    2016-10-01

    In this paper, we observed physically adsorbed CO molecules on C60 surface being displaced by impinging noble gas atoms (He, Ne, Ar, Kr), either through a dynamic displacement process or an exothermic replacement process, depending on their adsorption energies. This displacement mechanism could shift from one to the other depending on the surface coverage and temperature. Furthermore, rotational energy of the impinging molecules may also contribute to the dynamic displacement process by supplying additional energy.

  15. Surface-enhanced Raman Scattering from Molecules Adsorbed on Mixed Silver/Gold Nanoparticle Surfaces

    Institute of Scientific and Technical Information of China (English)

    FANG Jing-huai; HUANG Yun-xia; LI Xia; DOU Xiao-ming

    2004-01-01

    @@ Introduction Since the first discovery of Surface-Enhanced Raman Scattering(SERS) from pyridine molecules adsorbed at roughened silver electrodes in 1974 by Fleischmann et al.[1],the research of SERS has made tremendous progress in applications of it to various fields of science and technology[2-8].

  16. Mechanism of melting in submonolayer films of nitrogen molecules adsorbed on the basal planes of graphite

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Bruch, Ludwig Walter; Taub, H.

    1995-01-01

    The melting mechanism in submonolayer films of N-2 molecules adsorbed on the basal planes of graphite is studied using molecular-dynamics simulations. The melting is strongly correlated with the formation of vacancies in the films. As the temperature increases, the edges of the submonolayer patch...

  17. On stabilization of free radicals under γ-irradiation of molecules adsorbed by zeolites

    International Nuclear Information System (INIS)

    Investigated are ESR spectra and stability of free radicals forming as a result of γ-irradiation at -196 deg of triethylbenzol, diethyl spirit of dimethylmalon acid and tret butylbenzol, sorbed by NaX and CaX zeolites at room and increased temperatures. Anomalously high stability is characteristic only of radicals formed of γ-irradiated molecules, traversing close to the diameter of zeolite entry windows. The obtained data testifies to the effect that radiospectroscopy in combination with radiation effect on the adsorbed substances can successfully be used as the most sensitive method for porous structure characteristic of mineral adsorbents, in particular, for direct investigation of activized physical adsorption processes

  18. On-surface magnetochemistry: controlling spins in adsorbed molecules by a chemical switch

    International Nuclear Information System (INIS)

    Full text: We are interested in controlling the magnetic properties of paramagnetic molecules adsorbed on ferromagnetic substrates. The transition-metal ions in the surface-adsorbed porphyrins / phthalocyanines have a free top site for an additional ligand to bind and to control the magnetic properties of the on-surface complex. We show switching-off, tuning and switching-on the magnetic moments in the adsorbed complexes. Because of the interaction with the surface, the exact outcome of those reactions can be different. The axial-ligand allows to modify this interaction and can thus be used to control the exchange-interaction with the substrate. We combine element specific x-ray magnetic circular dichroism (XMCD) with STM and DFT+U. (author)

  19. Rod-like cyanophenyl probe molecules nanoconfined to oxide particles: Density of adsorbed surface species

    Science.gov (United States)

    Frunza, Stefan; Frunza, Ligia; Ganea, Constantin Paul; Zgura, Irina; Brás, Ana Rita; Schönhals, Andreas

    2016-02-01

    Surface layers have already been observed by broadband dielectric spectroscopy for composite systems formed by adsorption of rod-like cyanophenyl derivates as probe molecules on the surface of oxide particles. In this work, features of the surface layer are reported; samples with different amounts of the probe molecules adsorbed onto oxide (nano) particles were prepared in order to study their interactions with the surface. Thermogravimetric analysis (TGA) was applied to analyze the amount of loaded probe molecules. The density of the surface species ns was introduced and its values were estimated from quantitative Fourier transform infrared spectroscopy (FTIR) coupled with TGA. This parameter allows discriminating the composites into several groups assuming a similar interaction of the probe molecules with the hosts of a given group. An influence factor H is further proposed as the ratio of the number of molecules in the surface layer showing a glassy dynamics and the number of molecules adsorbed tightly on the surface of the support: It was found for aerosil composites and used for calculating the maximum filling degree of partially filled silica MCM-41 composites showing only one dielectric process characteristic for glass-forming liquids and a bulk behavior for higher filling degrees.

  20. Modeling the binding of fulvic acid by goethite: the speciation of adsorbed FA molecules

    Science.gov (United States)

    Filius, Jeroen D.; Meeussen, Johannes C. L.; Lumsdon, David G.; Hiemstra, Tjisse; van Riemsdijk, Willem H.

    2003-04-01

    Under natural conditions, the adsorption of ions at the solid-water interface may be strongly influenced by the adsorption of organic matter. In this paper, we describe the adsorption of fulvic acid (FA) by metal(hydr)oxide surfaces with a heterogeneous surface complexation model, the ligand and charge distribution (LCD) model. The model is a self-consistent combination of the nonideal competitive adsorption (NICA) equation and the CD-MUSIC model. The LCD model can describe simultaneously the concentration, pH, and salt dependency of the adsorption with a minimum of only three adjustable parameters. Furthermore, the model predicts the coadsorption of protons accurately for an extended range of conditions. Surface speciation calculations show that almost all hydroxyl groups of the adsorbed FA molecules are involved in outer sphere complexation reactions. The carboxylic groups of the adsorbed FA molecule form inner and outer sphere complexes. Furthermore, part of the carboxylate groups remain noncoordinated and deprotonated.

  1. Kondo effect of an adsorbed cobalt phthalocyanine (CoPc) molecule: the role of quantum interference

    OpenAIRE

    Chiappe, G.; Louis, E.

    2006-01-01

    A recent experimental study showed that, distorting a CoPc molecule adsorbed on a Au(111) surface, a Kondo effect is induced with a temperature higher than 200 K. We examine a model in which an atom with strong Coulomb repulsion (Co) is surrounded by four atoms on a square (molecule lobes), and two atoms above and below it representing the apex of the STM tip and an atom on the gold surface (all with a single, half-filled, atomic orbital). The Hamiltonian is solved exactly for the isolated cl...

  2. Functionalisation of the hinge region in receptor molecules for explosive detection

    DEFF Research Database (Denmark)

    Krebs, Frederik C

    2003-01-01

    The functionalisation of the hinge region in a molecular tweezer molecule showing a strong binding to explosives is presented. Two versatile functional groups are introduced, a carboxylic acid and a bromine atom. (C) 2003 Elsevier Ltd. All rights reserved.......The functionalisation of the hinge region in a molecular tweezer molecule showing a strong binding to explosives is presented. Two versatile functional groups are introduced, a carboxylic acid and a bromine atom. (C) 2003 Elsevier Ltd. All rights reserved....

  3. Can circular dichroism in core-level photoemission provide a spectral fingerprint of adsorbed chiral molecules?

    Energy Technology Data Exchange (ETDEWEB)

    Allegretti, F [Physics Department, University of Warwick, Coventry CV4 7AL (United Kingdom); Polcik, M [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D 14195 Berlin (Germany); Sayago, D I [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D 14195 Berlin (Germany); Demirors, F [Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D 14195 Berlin (Germany); O' Brien, S [Physics Department, University of Warwick, Coventry CV4 7AL (United Kingdom); Nisbet, G [Centre for Applied Catalysis, Department of Chemical and Biological Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH (United Kingdom); Lamont, C L A [Centre for Applied Catalysis, Department of Chemical and Biological Sciences, University of Huddersfield, Queensgate, Huddersfield HD1 3DH (United Kingdom); Woodruff, D P [Physics Department, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2005-04-01

    The results of experimental measurements and theoretical simulations of circular dichroism in the angular distribution (CDAD) of photoemission from atomic core levels of each of the enantiomers of a chiral molecule, alanine, adsorbed on Cu(1 1 0) are presented. Measurements in, and out of, substrate mirror planes allow one to distinguish the CDAD due to the chirality of the sample from that due to a chiral experimental geometry. For these studies of oriented chiral molecules, the CDAD is seen not only in photoemission from the molecular chiral centre, but also from other atoms which have chiral geometries as a result of the adsorption. The magnitude of the CDAD due to the sample chirality differs for different adsorption phases of alanine, and for different emission angles and energies, but is generally small compared with CDAD out of the substrate mirror planes which is largely unrelated to the molecular chirality. While similar measurements of other molecules may reveal larger CDAD due to molecular chirality, the fact that the results for one chiral molecule show weak effects means that such CDAD is unlikely to provide a simple and routine general spectral fingerprint of adsorbed molecular chirality.

  4. Large Relative Raman Shift for Molecules Adsorbed on Metallic Nano-particles

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-Yun; XIA Yu-Xing; ZHAN Li; LENG Jiang-Hua

    2008-01-01

    The enhancement of two order-of-magnitudes is observed in surface-enhanced Raman spectroscopy (SERS) of gases (CO, C2H2, C2H4, etc) adsorbed on nitric acid-roughened metal foil. In addition, some Raman lines of gases adsorbed on these active substrates show larger frequency shifts and linewidth broadening, compared with the Raman spectroscopy of free gases. Using the two-oscillator electromagnetic model, we explain this phenomenon. It is related to the large non-regular particles on the active substrate we prepared. It is found that the parameters of the surface-plasmon dispersion, the distance of molecules from the surface and the radius of particles play crucial roles on the relative large Raman shifts.

  5. Ultra-sensitive fluorescence spectroscopy of isolated surface-adsorbed molecules using an optical nanofiber.

    Science.gov (United States)

    Stiebeiner, A; Rehband, O; Garcia-Fernandez, R; Rauschenbeutel, A

    2009-11-23

    The strong radial confinement and the pronounced evanescent field of the guided light in optical nanofibers yield favorable conditions for ultra-sensitive surface spectroscopy of molecules deposited on the fiber. Using the guided mode of the nanofiber for both excitation and fluorescence collection, we present spectroscopic measurements on 3,4,9,10-perylenetetracarboxylic dianhydride molecules (PTCDA) at ambient conditions. Surface coverages as small as 1 per thousand of a compact monolayer still give rise to fluorescence spectra with a good signal to noise ratio. Moreover, we analyze and quantify the self-absorption effects due to reabsorption of the emitted fluorescence light by circumjacent surface-adsorbed molecules distributed along the fiber waist. PMID:19997412

  6. Homeotropic orientation of a nematic liquid crystal by bent-core molecules adsorbed on its surface

    Science.gov (United States)

    Hwang, Jiyong; Yang, Seungbin; Lee, Hyojin; Kim, Jongyoon; Lee, Ji-Hoon; Kang, Shin-Woong; Choi, E.-Joon

    2015-06-01

    We reported the promotion of a homeotropic alignment of a nematic liquid crystal (NLC) by bent-core liquid-crystal (BLC) Molecules adsorbed its surface. The BLC was mixed at various concentrations with the NLC, and the mixtures were injected into an empty cell with a cell gap of 13 μm. Although the pure NLC showed a heterogeneous orientation, the BLC-NLC mixture was gradually transformed to a homeotropic alignment with increasing concentration of the BLC. We investigated the surface topography of the samples by using an atomic force microscopy (AFM) and found that the BLC molecules were segregated into a polyimide (PI) surface and formed protrusion domains with diameters of 50-100 nm. The BLC protrusions might promote the homeotropic orientation of the NLC molecules.

  7. Fossils, molecules and embryos: new perspectives on the Cambrian explosion

    Science.gov (United States)

    Valentine, J. W.; Jablonski, D.; Erwin, D. H.

    1999-01-01

    The Cambrian explosion is named for the geologically sudden appearance of numerous metazoan body plans (many of living phyla) between about 530 and 520 million years ago, only 1.7% of the duration of the fossil record of animals. Earlier indications of metazoans are found in the Neoproterozic; minute trails suggesting bilaterian activity date from about 600 million years ago. Larger and more elaborate fossil burrows appear near 543 million years ago, the beginning of the Cambrian Period. Evidence of metazoan activity in both trace and body fossils then increased during the 13 million years leading to the explosion. All living phyla may have originated by the end of the explosion. Molecular divergences among lineages leading to phyla record speciation events that have been earlier than the origins of the new body plans, which can arise many tens of millions of years after an initial branching. Various attempts to date those branchings by using molecular clocks have disagreed widely. While the timing of the evolution of the developmental systems of living metazoan body plans is still uncertain, the distribution of Hox and other developmental control genes among metazoans indicates that an extensive patterning system was in place prior to the Cambrian. However, it is likely that much genomic repatterning occurred during the Early Cambrian, involving both key control genes and regulators within their downstream cascades, as novel body plans evolved.

  8. Thermal and Electronic Fluctuations of Flexible Adsorbed Molecules: Azobenzene on Ag(111)

    Science.gov (United States)

    Maurer, Reinhard J.; Liu, Wei; Poltavsky, Igor; Stecher, Thomas; Oberhofer, Harald; Reuter, Karsten; Tkatchenko, Alexandre

    2016-04-01

    We investigate the thermal and electronic collective fluctuations that contribute to the finite-temperature adsorption properties of flexible adsorbates on surfaces on the example of the molecular switch azobenzene C12 H10 N2 on the Ag(111) surface. Using first-principles molecular dynamics simulations, we obtain the free energy of adsorption that accurately accounts for entropic contributions, whereas the inclusion of many-body dispersion interactions accounts for the electronic correlations that govern the adsorbate binding. We find the adsorbate properties to be strongly entropy driven, as can be judged by a kinetic molecular desorption prefactor of 1024 s-1 that largely exceeds previously reported estimates. We relate this effect to sizable fluctuations across structural and electronic observables. A comparison of our calculations to temperature-programed desorption measurements demonstrates that finite-temperature effects play a dominant role for flexible molecules in contact with polarizable surfaces, and that recently developed first-principles methods offer an optimal tool to reveal novel collective behavior in such complex systems.

  9. Formaldehyde molecule adsorbed on doped graphene: A first-principles study

    Science.gov (United States)

    Liu, Xu-Ying; Zhang, Jian-Min

    2014-02-01

    Adsorption of formaldehyde (H2CO) on B-, N-, Si-, Al-, Cr-, Mn-, and Au-doped graphene was theoretically studied using first-principles approach based on density functional theory in order to exploit their potential applications as H2CO gas sensors. The electronic and magnetic properties of the graphene-molecule adsorption adducts are strongly dependent on the dopants. H2CO molecule is adsorbed weakly on B- and N-doped graphene; in general, strong chemisorption is observed on Si-, Al-, Cr-, Mn-, and Au-doped graphene. The most stable adsorption geometries, adsorption energies, magnetic moments, charge transfers, and density of states of these systems are thoroughly discussed. This work reveals that the sensitivity of graphene-based chemical gas sensors for H2CO can be drastically improved by introducing appropriate dopant. Al and Mn are found to be the best choices among all the dopants.

  10. Formaldehyde molecule adsorbed on doped graphene: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Xu-Ying; Zhang, Jian-Min, E-mail: jianm_zhang@yahoo.com

    2014-02-28

    Adsorption of formaldehyde (H{sub 2}CO) on B-, N-, Si-, Al-, Cr-, Mn-, and Au-doped graphene was theoretically studied using first-principles approach based on density functional theory in order to exploit their potential applications as H{sub 2}CO gas sensors. The electronic and magnetic properties of the graphene-molecule adsorption adducts are strongly dependent on the dopants. H{sub 2}CO molecule is adsorbed weakly on B- and N-doped graphene; in general, strong chemisorption is observed on Si-, Al-, Cr-, Mn-, and Au-doped graphene. The most stable adsorption geometries, adsorption energies, magnetic moments, charge transfers, and density of states of these systems are thoroughly discussed. This work reveals that the sensitivity of graphene-based chemical gas sensors for H{sub 2}CO can be drastically improved by introducing appropriate dopant. Al and Mn are found to be the best choices among all the dopants.

  11. Uenbinding'' an adsorbed organic molecule: K plus PTCDA on Ag(110)

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Oliver; Schmitz, Christoph H.; Fiedler, Benjamin; Sokolowski, Moritz [Institut fuer Physikalische und Theoretische Chemie, Universitaet Bonn (Germany); Mercurio, Giuseppe; Subach, Sergey; Tautz, Frank Stefan [Institut fuer Bio- und Nanosysteme 3, Forschungszentrum Juelich (Germany)

    2010-07-01

    We have doped the well-known brick-wall structure of pristine PTCDA which is present in the monolayer on the Ag(110) surface with potassium (K) and investigated the induced structural and electronic changes at the interface. SPA-LEED measurements reveal that the structural order of the PTCDA molecules is strongly altered upon K dosing: A variety of co-existing binary phases is observed within the monolayer. In addition we have conducted XPS and NIXSW measurements on K+PTCDA/Ag(110). The photoemission experiments indicate that the K atoms preferentially interact with the carboxylic groups of the co-adsorbed PTCDA molecules. This interpretation is further supported by the NIXSW results: The adsorption geometries of the carboxylic and the anhydride oxygen (O) atoms are highly influenced by the presence of K on the surface, the bonding distances are extended. The adsorption height of the perylene core is also increased by K doping. Hence we conclude that the local Ag-O bonds at the interface are partially lifted by the co-adsorbed K and that K and Ag atoms compete for the interaction with the carboxylic groups of PTCDA while the bonding across the interface is weakened.

  12. Mechanism of charge transfer and its impacts on Fermi-level pinning for gas molecules adsorbed on monolayer WS2

    International Nuclear Information System (INIS)

    Density functional theory calculations were performed to assess changes in the geometric and electronic structures of monolayer WS2 upon adsorption of various gas molecules (H2, O2, H2O, NH3, NO, NO2, and CO). The most stable configuration of the adsorbed molecules, the adsorption energy, and the degree of charge transfer between adsorbate and substrate were determined. All evaluated molecules were physisorbed on monolayer WS2 with a low degree of charge transfer and accept charge from the monolayer, except for NH3, which is a charge donor. Band structure calculations showed that the valence and conduction bands of monolayer WS2 are not significantly altered upon adsorption of H2, H2O, NH3, and CO, whereas the lowest unoccupied molecular orbitals of O2, NO, and NO2 are pinned around the Fermi-level when these molecules are adsorbed on monolayer WS2. The phenomenon of Fermi-level pinning was discussed in light of the traditional and orbital mixing charge transfer theories. The impacts of the charge transfer mechanism on Fermi-level pinning were confirmed for the gas molecules adsorbed on monolayer WS2. The proposed mechanism governing Fermi-level pinning is applicable to the systems of adsorbates on recently developed two-dimensional materials, such as graphene and transition metal dichalcogenides

  13. Cross-sectional scanning probe microscopy on GaAs: Tip-induced band bending, buried acceptors and adsorbed molecules

    OpenAIRE

    Münnich, Gerhard

    2014-01-01

    This thesis presents low temperature scanning probe experiments performed in the cross-sectional geometry (X-SPM) on GaAs samples. In particular, three topics have been addressed. First, the GaAs(110) surface has been utilized as a substrate to adsorb iron-II-phthalocyanine molecules. The molecules were probed from scanning tunneling microscopy (STM) and spectroscopy (STS) and were found to be only weakly perturbed by the substrate. This is in analogy to molecules decoupled from a metalli...

  14. Imaging the wave functions of adsorbed molecules using angle-resolved photoemmision data

    Science.gov (United States)

    Lüftner, Daniel; Ules, Thomas; Reinisch, Eva Maria; Koller, Georg; Soubatch, Serguei; Tautz, F. Stefan; Ramsey, Michael G.; Puschnig, Peter

    2014-03-01

    The frontier electronic orbitals of molecules are the prime determinants of the respective compounds' chemical, electronic, and optical properties. Although orbitals are very powerful concepts, experimentally only the electron densities and energy levels are directly observable. As has been shown in recent publications, angle-resolved photoemission (ARPES) intensity maps of organic molecular layers are related to the absolute value of the Fourier transform of the initial state molecular orbital. However, the lost phase information impedes the back-transformation of the orbital into real space. Here, we show how molecular orbital images as well as the absent phase information can be retrieved by applying an iterative procedure which takes experimental ARPES maps as input and only assumes spatial confinement of the orbital. The method is demonstrated for several molecular orbitals of two proto-typical pi-conjugated molecules: the LUMO, HOMO, and HOMO-1 of pentacene, and the LUMO and HOMO of PTCDA. The technique is simple and robust and further emphasizes the capabilities of ARPES looking at spatial distributions of wave functions of adsorbed molecules thereby complementing data obtained from scanning probe methods.

  15. Room temperature differential conductance measurements of triethylamine molecules adsorbed on Si(001).

    Science.gov (United States)

    Naitabdi, Ahmed; Rochet, François; Carniato, Stéphane; Bournel, Fabrice; Gallet, Jean-Jacques

    2016-08-17

    We have measured the differential conductance of the triethylamine molecule (N(CH2CH3)3) adsorbed on Si(001)-2 × 1 at room temperature using scanning tunneling spectroscopy. Triethylamine can be engaged in a dative bonding with a silicon dimer, forming a Si-Si-N(CH2CH3)3 unit. We have examined the datively bonded adduct, either as an isolated molecule, or within an ordered molecular domain (reconstructed 4 × 2). The differential conductance curves, supported by DFT calculations, show that in the explored energy window (±2.5 near the Fermi level) the main features stem from the uncapped dangling bonds of the reacted dimer and of the adjacent unreacted ones that are electronically coupled The formation of a molecular domain, in which one dimer in two is left unreacted, is reflected in a shift of the up dimer atom occupied level away from the Fermi level, likely due to an increased π-bonding strength. In stark contrast with the preceding, pairs of dissociated molecule (a minority species) are electronically decoupled from the dimer dangling bond states. DFT calculation show that the lone-pair of the Si-N(CH2CH3)2 is a shallow level, that is clearly seen in the differential conductance curve. PMID:27499070

  16. Effect of resonance dipole-dipole interaction on spectra of adsorbed SF6 molecules.

    Science.gov (United States)

    Dobrotvorskaia, Anna N; Kolomiitsova, Tatiana D; Petrov, Sergey N; Shchepkin, Dmitriy N; Smirnov, Konstantin S; Tsyganenko, Alexey A

    2015-09-01

    Adsorption of SF6 on zinc oxide and on silicalite-1 was investigated by a combination of IR spectroscopy with the calculations of spectra by means of a modernized model, developed previously for liquids. Comparison of the experimental spectra and the results of modeling shows that the complex band shapes in spectra of adsorbed molecules with extremely high absorbance are due to the strong resonance dipole-dipole interaction (RDDI) rather that the surface heterogeneity or the presence of specific surface sites. Perfect agreement between calculated and observed spectra was found for ZnO, while some dissimilarity in band intensities for silicalite-1 was attributed to complicated geometry of molecular arrangement in the channels. PMID:25897721

  17. Correlation Between Energy Transfer Rate and Atomization Energy of Some Trinitro Aromatic Explosive Molecules

    Institute of Scientific and Technical Information of China (English)

    Su-hong Ge; Xin-lu Cheng; Zheng-lai Liu; Xiang-dong Yang; Fang-fang Dong

    2008-01-01

    An assumptive theoretical relationship is suggested to describe the property of molecular atomization energy and energy transfer rate in the initiation of explosions. To investigate the relationship between atomization energy and energy transfer rate, the number of doorway modes of explosives is estimated by the theory of Dlott and Fayer in which the rate is proportional to the number of normal mode vibrations. It was evaluated frequencies of normal mode vibrations of eight molecules by means of density functional theory (DFT) at the b3p86/6-31G(d,p) level. It is found that the number of doorway modes shows a linear correlation to the atomization energies of the molecules, which were also calculated by means of the same method. A mechanism of this correlation is discussed. It is also noted that in those explosives with similar molecular structure and molecular weight, the correlation between the atomization energy and the number of doorway modes is higher.

  18. Structure and dynamics of monolayer films of squalane molecules adsorbed on a solid surface

    Science.gov (United States)

    D. T Enevoldsen, A.; Hansen, F. Y.; Diama, A.; Taub, H.

    2003-03-01

    Squalane is a branched alkane (C_30H_62). It consists of a straight chain with 24 carbon atoms, as in tetracosane (C_24H_50), and has six methyl side groups. Branched polymers such as squalane are thought to be better lubricants than n-alkanes. At low temperature, our molecular dynamics (MD) simulations show that the molecules form an ordered monolayer which melts at approximately 325 K compared to the tetracosane monolayer melting point of ˜ 340 K. Our MD simulations indicate the same melting mechanism in the squalane monolayer that was found previously for tetracosane (F. Y. Hansen and H. Taub, Phys. Rev. Lett. 69, 652 (1992).) They also show that the adsorbed molecules are distorted from an all-trans carbon backbone in contrast to what was found for tetracosane. This may explain why the Bragg diffraction peaks were observed to be broader for the squalane monolayer than for tetracosane (D. Fuhrmann, A. P. Graham, L. Criswell, H. Mo, B. Matthies, K. W. Herwig, and H. Taub, Surf. Sci. 482-485, 77 (2001).). The diffusive motion in a squalane monolayer has been investigated by both quasielastic neutron scattering and MD simulations and compared to the dynamics in tetracosane monolayers. Focus will be on differences in the dynamics.

  19. Brownian dynamics simulation of peeling a strongly-adsorbed polymer molecule from a frictionless substrate.

    Science.gov (United States)

    Iliafar, Sara; Vezenov, Dmitri; Jagota, Anand

    2013-02-01

    We used brownian dynamics to study the peeling of a polymer molecule, represented by a freely jointed chain, from a frictionless surface in an implicit solvent with parameters representative of single-stranded DNA adsorbed on graphite. For slow peeling rates, simulations match the predictions of an equilibrium statistical thermodynamic model. We show that deviations from equilibrium peeling forces are dominated by a combination of Stokes (viscous) drag forces acting on the desorbed section of the chain and a finite rate of hopping over a desorption barrier. Characteristic velocities separating equilibrium and nonequilibrium regimes are many orders of magnitude higher than values accessible in force spectroscopy experiments. Finite probe stiffness resulted in disappearance of force spikes due to desorption of individual links predicted by the statistical thermodynamic model under displacement control. Probe fluctuations also masked sharp transitions in peeling force between blocks of distinct sequences, indicating limitation in the ability of single-molecule force spectroscopy to distinguish small differences in homologous molecular structures.

  20. Observation and analysis of Fano-like lineshapes in the Raman spectra of molecules adsorbed at metal interfaces

    OpenAIRE

    Dey, S; Banik, M; Hulkko, E.; Rodriguez, K.; Apkarian, V. A.; Galperin, M.; Nitzan, A.

    2015-01-01

    Surface enhanced Raman spectra from molecules (bipyridyl ethylene) adsorbed on gold dumbells are observed to become increasingly asymmetric (Fano-like) at higher incident light intensity. The electronic temperature (inferred from the anti-Stokes (AS) electronic Raman signal increases at the same time while no vibrational AS scattering is seen. These observations are analyzed by assuming that the molecule-metal coupling contains an intensity dependent contribution (resulting from light-induced...

  1. Nature of free-electron-like states in PTCDA molecules adsorbed on an Ag(111) surface

    Energy Technology Data Exchange (ETDEWEB)

    Persson, Mats; Dyer, Matthew [Surface Science Research Centre, University of Liverpool, L69 3BX Liverpool (United Kingdom)

    2009-07-01

    Advances in molecular assembly experiments on metal surfaces and potential applications arising from them call for a better understanding of the electronic structure at the interface of metals and organic systems. There is a high interest in delocalized electronic states, because of their potential use in molecular and opto-electronics applications. Recently, unoccupied, free-electron-like states arising in mono layers of 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA) molecules adsorbed on an Ag(111) surface at energies close to the Fermi energy have been observed by scanning tunneling and photoemission spectroscopies. So as to reveal the nature of these delocalized states we have carried out a density functional study of the electronic structure and local density of states of these systems. We show that the observed free-electron state originates from a Shockley surface state (SS) at the zone centre of the bare surface. The SS is shifted up by the interaction with the organic overlayer.

  2. Nuclear magnetic resonance study of the structure of simple molecules adsorbed on metal surfaces: acetylene on platinum

    International Nuclear Information System (INIS)

    We have used NMR to determine the structure of acetylene (HC - CH) adsorbed at room temperature on small platinum particles by studying the 13C-13C, 13C-1H, and 1H-1H dipolar interactions among the nuclei in the adsorbed molecules. We find a model of 77% CCH2 and 23% HCCH to be the only one consistent with all of our data. The C-C bond length of the majority species, CCH2, is determined as 1.44 +- 0.02 A, midway between a single and double bond, suggesting that both carbon atoms bond to the surface. 36 references, 29 figures, 1 table

  3. Magnetic transitions induced by tunneling electrons in individual adsorbed M-phthalocyanine molecules (M=Fe and Co)

    OpenAIRE

    Gauyacq, J. P.; Novaes, Frederico D; Lorente, N.

    2010-01-01

    We report on a theoretical study of magnetic transitions induced by tunnelling electrons in individual adsorbed M-Phthalocyanine (M-Pc) molecules where M is a metal atom: Fe-Pc on a Cu(110)(2$\\times$1)-O surface and Co-Pc layers on Pb(111) islands. The magnetic transitions correspond to the change of orientation of the spin angular momentum of the metal ion with respect to the surroundings and possibly an applied magnetic field. The adsorbed Fe-Pc system is studied with a Density Functional T...

  4. Direct comparison of the electronic coupling efficiency of sulfur and selenium alligator clips for molecules adsorbed onto gold electrodes

    International Nuclear Information System (INIS)

    Scanning tunneling microscopy experiments have been performed to compare the electronic coupling provided by S and by Se used as alligator clips for bisthiol- and biselenol-terthiophene molecules adsorbed onto gold. The molecules were inserted in a dodecanethiol (DT) self-assembled monolayer. Their apparent height above the dodecanethiol matrix was used as a measure of the electronic coupling strength corresponding to S and Se, respectively. We show that the insertion behaviors of the two molecules are qualitatively the same, and that Se provides systematically a better coupling link than S, whatever the tunneling conditions

  5. Effects of molecule-insulator interaction on geometric property of a single phthalocyanine molecule adsorbed on an ultrathin NaCl film

    Science.gov (United States)

    Miwa, Kuniyuki; Imada, Hiroshi; Kawahara, Shota; Kim, Yousoo

    2016-04-01

    The adsorption structure and orientation of a metal-free phthalocyanine (H2Pc ) and a magnesium phthalocyanine (MgPc) on a bilayer of NaCl films were investigated both theoretically and experimentally by means of first-principles calculations based on density functional theory and by scanning tunneling microscopy. H2Pc is adsorbed with its center over the sodium cation, and H-N bonds in the molecule are aligned with the [100] or [010] surface direction of a bilayer (001)-terminated NaCl film. The most stable structures of MgPc on the NaCl film show two kinds of orientations corresponding to the molecule rotated by ±7∘ relative to the [110] surface direction, with the Mg cation positioned over the chlorine anion in both cases. The energetic barrier for switching between these orientations is as low as 9.0 meV, and during an STM measurement, an orientational change of MgPc can be observed. The interaction between the adsorbed molecule and the NaCl film were analyzed in terms of dispersion interaction, Mg-Cl chemical bonding, and electrostatic interaction. It is found that the small electrostatic interaction between the molecule and the film gives a dominant contribution to determining the molecular orientation. Our detailed and comprehensive studies of the molecule-insulator interaction will provide knowledge to understand and control the properties of molecules on an insulating material.

  6. HCI-induced molecule fragmentation: non-Coulombic explosion and three-body effects

    International Nuclear Information System (INIS)

    The study of highly charged ion-induced diatomic (CO) and triatomic (CO2) molecules fragmentation by the coincident measurement of the fragment momenta is presented. It is shown that the experimental results together with ab initio calculations including a large number of potential energy curves evidence the limitation of the Coulomb explosion model to reproduce the dynamics of the fragmentation. The geometry modification of the CO2 molecule during the breakup is explored and the concerted or sequential nature of the dissociation is discussed for two fragmentation channels. Finally, the fragmentation of the H2 molecules following collisions with slow multicharged ions is analysed for various projectiles and energies. From the energy spectra, the effect of the projectile on the H+ fragments is evidenced. This three-body effect is discussed in connection with the results of two model calculations including or not the role of the projectile. (orig.)

  7. Preparation of theoretical scanning tunneling microscope images of adsorbed molecules: a theoretical study of benzene on the Cu(110) surface

    International Nuclear Information System (INIS)

    Full text: Since its development in 1982, the Scanning Tunneling Microscope (STM) has developed into a powerful tool for the study of surfaces and adsorbates. However, the utility of the technique can be further enhanced through the development of techniques for generating theoretical STM images. This is particularly true when studying molecules adsorbed on a substrate, as the results are often interpreted superficially due to an inadequate understanding of the orbital overlap probed in the experiment. A method of preparing theoretical scanning tunneling microscope (STM) images using comparatively inexpensive desktop computers and the commercially available CRYSTAL98 package is presented through a study of benzene adsorbed on the Cu(110) surface. Density Functional Theory (DFT) and Hartree-Fock (HF) methods are used to model clean Cu(110) slabs of various thicknesses and to simulate the adsorption of benzene onto these slabs. Eight possible orientations of benzene on the Cu(110) surface are proposed, and the optimum orientation according to the calculations is presented. Theoretical STM images of the Cu(110) surface and benzene adsorbed on the Cu(110) surface are compared with experimental STM images of the system from a published study. Significant differences are observed and are examined in detail

  8. Adsorption energy and geometry of adsorbed organic molecules on Au(111) probed by surface-state photoemission

    Energy Technology Data Exchange (ETDEWEB)

    Ziroff, Johannes; Forster, Frank [Universitaet Wuerzburg, Experimentelle Physik II, D-97074 Wuerzburg (Germany); Reinert, Friedrich [Universitaet Wuerzburg, Experimentelle Physik II, D-97074 Wuerzburg (Germany); Forschungszentrum Karlsruhe, Gemeinschaftslabor fuer Nanoanalytik, D-76021 Karlsruhe (Germany)

    2009-07-01

    The modification of the Au(111) surface states by an adsorbed monolayer of large {pi}-conjugated molecules (PTCDA, NTCDA, CuPc) was investigated by high-resolution angle-resolved photoelectron spectroscopy. We determined binding energy, band mass, and Rashba-splitting and discuss the results in the context of rare-gas adsorption on noble metals. This comparison allows the determination of the bonding strength of the adsorbates, found to be physisorptive with derived binding energies per molecule of 2.0 eV for PTCDA and 1.5 eV for NTCDA. We will also present a superstructure model for the NTCDA/Au(111) system, deduced from low energy electron diffraction images in combination with band-backfolding of the Tamm and Shockley states. The coverage dependent evolution of the surface states was also investigated for the three molecules, giving evidence for a dilute-phase growth of the CuPc molecule on the Au(111) surface.

  9. Charge-transfer photodissociation of adsorbed molecules via electron image states

    CERN Document Server

    Jensen, E T

    2007-01-01

    The 248nm and 193nm photodissociation of submonolayer quantities of CH$_3$Br and CH$_3$I adsorbed on thin layers of n-hexane indicate that the dissociation is caused by dissociative electron attachment from sub-vacuum level photoelectrons created in the copper substrate. The characteristics of this photodissociation-- translation energy distributions and coverage dependences show that the dissociation is mediated by an image potential state which temporarily traps the photoelectrons near the n-hexane--vacuum interface, and then the charge transfers from this image state to the affinity level of a co-adsorbed halomethane which then dissociates.

  10. Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films

    Energy Technology Data Exchange (ETDEWEB)

    Kenny, T.W.

    1989-05-01

    Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of /sup 4/He adsorbed on metallic films. In contrast to measurements of /sup 4/He adsorbed on all other insulating substrates, we have shown that /sup 4/He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, /sup 4/He adsorbed on sapphire and on Ag films and H/sub 2/ adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs.

  11. Heat capacity measurements of atoms and molecules adsorbed on evaporated metal films

    International Nuclear Information System (INIS)

    Investigations of the properties of absorbed monolayers have received great experimental and theoretical attention recently, both because of the importance of surface processes in practical applications such as catalysis, and the importance of such systems to the understanding of the fundamentals of thermodynamics in two dimensions. We have adapted the composite bolometer technology to the construction of microcalorimeters. For these calorimeters, the adsorption substrate is an evaporated film deposited on one surface of an optically polished sapphire wafer. This approach has allowed us to make the first measurements of the heat capacity of submonolayer films of 4He adsorbed on metallic films. In contrast to measurements of 4He adsorbed on all other insulating substrates, we have shown that 4He on silver films occupies a two-dimensional gas phase over a broad range of coverages and temperatures. Our apparatus has been used to study the heat capacity of Indium flakes. CO multilayers, 4He adsorbed on sapphire and on Ag films and H2 adsorbed on Ag films. The results are compared with appropriate theories. 68 refs., 19 figs

  12. Coulomb explosion of CS2 molecule under an intense femtosecond laser field

    Science.gov (United States)

    Xiao, Wang; Jian, Zhang; Shi-An, Zhang; Zhen-Rong, Sun

    2016-05-01

    We experimentally demonstrate the Coulomb explosion process of CS2 molecule under a near-infrared (800 nm) intense femtosecond laser field by a DC-sliced ion imaging technique. We obtain the DC-sliced images of these fragment ions S+, S2+, CS+, and CS2+ by breaking one C–S bond, and assign their Coulomb explosion channels by considering their kinetic energy release and angular distribution. We also numerically simulate the dissociation dynamics of parent ions by a Coulomb potential approximation, and obtain the time evolution of Coulomb energy and kinetic energy release, which indicates that the dissociation time of parent ions decreases with the increase of the charge number k. These experimental and theoretical results can serve as a useful benchmark for those researchers who work in the related area. Project supported by the National Natural Science Foundation of China (Grant Nos. 51132004 and 11474096), and the Science and Technology Commission of Shanghai Municipality, China (Grant No. 14JC1401500). We acknowledge the support of the NYU-ECNU Institute of Physics at NYU Shanghai, China.

  13. Electric-field-dependent empirical potentials for molecules and crystals: a first application to flexible water molecule adsorbed in zeolites

    OpenAIRE

    Cicu, P.; Demontis, Pierfranco; Spanu, Silvano; Suffritti, Giuseppe Baldovino; Tilocca, Antonio

    2000-01-01

    A general method to include electric-field-dependent terms in empirical potential functions representing interatomic interactions is proposed. It is applied to derive an intramolecular potential model for the water molecule able to reproduce the effects of an electric field on its geometry and dynamics: to enlarge the HOH angle, to increase slightly the OH bond lengths, to red-shift the stretching vibrational frequencies, and to blue-shift slightly the bending mode frequency. These effects ha...

  14. Adsorbed states of chlorophenol on Cu(110) and controlled switching of single-molecule junctions

    Science.gov (United States)

    Okuyama, H.; Kitaguchi, Y.; Hattori, T.; Ueda, Y.; Ferrer, N. G.; Hatta, S.; Aruga, T.

    2016-06-01

    A molecular junction of substituted benzene (chlorophenol) is fabricated and controlled by using a scanning tunneling microscope (STM). Prior to the junction formation, the bonding geometry of the molecule on the surface is characterized by STM and electron energy loss spectroscopy (EELS). EELS shows that the OH group of chlorophenol is dissociated on Cu(110) and that the molecule is bonded nearly flat to the surface via an O atom, with the Cl group intact. We demonstrate controlled contact of an STM tip to the "available" Cl group and lift-up of the molecule while it is anchored to the surface via an O atom. The asymmetric bonding motifs of the molecule to the electrodes allow for reversible control of the junction.

  15. Mechanism of charge transfer and its impacts on Fermi-level pinning for gas molecules adsorbed on monolayer WS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Changjie; Zhu, Huili, E-mail: hlzhu@jmu.edu.cn [Department of Physics, School of Science, Jimei University, Xiamen 361021 (China); Yang, Weihuang [Division of Physics and Applied Physics, School of Physical and Mathematical Science, Nanyang Technological University, Singapore 637371 (Singapore)

    2015-06-07

    Density functional theory calculations were performed to assess changes in the geometric and electronic structures of monolayer WS{sub 2} upon adsorption of various gas molecules (H{sub 2}, O{sub 2}, H{sub 2}O, NH{sub 3}, NO, NO{sub 2}, and CO). The most stable configuration of the adsorbed molecules, the adsorption energy, and the degree of charge transfer between adsorbate and substrate were determined. All evaluated molecules were physisorbed on monolayer WS{sub 2} with a low degree of charge transfer and accept charge from the monolayer, except for NH{sub 3}, which is a charge donor. Band structure calculations showed that the valence and conduction bands of monolayer WS{sub 2} are not significantly altered upon adsorption of H{sub 2}, H{sub 2}O, NH{sub 3}, and CO, whereas the lowest unoccupied molecular orbitals of O{sub 2}, NO, and NO{sub 2} are pinned around the Fermi-level when these molecules are adsorbed on monolayer WS{sub 2}. The phenomenon of Fermi-level pinning was discussed in light of the traditional and orbital mixing charge transfer theories. The impacts of the charge transfer mechanism on Fermi-level pinning were confirmed for the gas molecules adsorbed on monolayer WS{sub 2}. The proposed mechanism governing Fermi-level pinning is applicable to the systems of adsorbates on recently developed two-dimensional materials, such as graphene and transition metal dichalcogenides.

  16. Slow Diffusive Motions in a Monolayer of Tetracosane Molecules Adsorbed on Graphite

    DEFF Research Database (Denmark)

    Taub, H.; Hansen, Flemming Yssing; Criswell, L.;

    2004-01-01

    Monolayers of intermediate-length alkane molecules such as tetracosane (n-C24H50 or C24) serve as prototypes for studying the interfacial dynamics of more complex polymers, including bilayer lipid membranes. Using high-resolution quasielastic neutron scattering (QNS) and exfoliated graphite...... to a temperature of similar to230 K, we observe the QNS energy width to be dispersionless, consistent with molecular dynamics simulations showing rotational motion of the molecules about their long axis. At 260 K, the QNS energy width begins to increase with wave vector transfer, suggesting onset of nonuniaxial...... rotational motion and bounded translational motion. We continue to observe QNS up to the monolayer melting temperature at similar to340 K where our simulations indicate that the only motion slow enough to be visible within our energy window results from the creation of gauche defects in the molecules....

  17. Some Features of Raman Scattering by Molecules Adsorbed on Metal Crystal Faces and a Fine Light Structure

    CERN Document Server

    Polubotko, A M

    2013-01-01

    The paper analyzes some experiments on Raman scattering by molecules adsorbed on the face (111) of silver monocrystals performed by A. Campion et al. From the existence of the forbidden line of benzene, the conclusion about existence of the surface field, caused by atomic structure of the surface is made. The relatively large intensity of this line allows to make a conclusion about large influence of the electromagnetic field spatial inhomogeneity in crystals on their optical properties. The difference between this field and a regular plane wave, which usually describes propagation of electromagnetic field in solids is named as a fine light structure. The influence of this structure on optical properties of solids is pointed out.

  18. Effects of non-local exchange on core level shifts for gas-phase and adsorbed molecules

    International Nuclear Information System (INIS)

    Density functional theory calculations are often used to interpret experimental shifts in core level binding energies. Calculations based on gradient-corrected (GC) exchange-correlation functionals are known to reproduce measured core level shifts (CLS) of isolated molecules and metal surfaces with reasonable accuracy. In the present study, we discuss a series of examples where the shifts calculated within a GC-functional significantly deviate from the experimental values, namely the CLS of C 1s in ethyl trifluoroacetate, Pd 3d in PdO and the O 1s shift for CO adsorbed on PdO(101). The deviations are traced to effects of the electronic self-interaction error with GC-functionals and substantially better agreements between calculated and measured CLS are obtained when a fraction of exact exchange is used in the exchange-correlation functional

  19. Switching orientation of adsorbed molecules: Reverse domino on a metal surface

    Science.gov (United States)

    Braatz, C. R.; Esat, T.; Wagner, C.; Temirov, R.; Tautz, F. S.; Jakob, P.

    2016-01-01

    A thus far unknown phase of 1,4,5,8-naphthalene-tetracarboxylic dianhydride (NTCDA) on Ag(111), characterized by an all perpendicular orientation of the planar molecules and bound to the Ag substrate through the carboxyl oxygen atoms has been identified using infrared absorption spectroscopy and scanning tunneling microscopy. Its formation process requires second layer NTCDA to squeeze into empty spaces between relaxed monolayer NTCDA molecules. Remarkably, this process causes initially parallel oriented NTCDA to likewise adopt the new, highly inclined adsorption geometry. According to our SPA-LEED and STM findings, the new phase displays a distinct long range order and shows a pronounced tendency to form 1D rows or narrow islands. We suggest that extra NTCDA preferentially transforms into the upright configuration close to existing islands and attaches to them, i.e. the transformation process proceeds in a directed and recurrent manner (reverse domino scenario). Identical processing starting with a compressed NTCDA/Ag(111) monolayer leads to a purely parallel oriented bilayer, that is, the NTCDA monolayer phase is retained and merely acts as a passive template for bilayer NTCDA. The new vertical NTCDA phase represents an unusual molecular system with π-orbitals oriented parallel to a metal surface. A substantially reduced coupling of these orbitals to Ag(111) electronic levels is conjectured, which will have a major impact on intermolecular couplings and electronically excited state lifetimes.

  20. Tribochemical synthesis of nano-lubricant films from adsorbed molecules at sliding solid interface: Tribo-polymers from α-pinene, pinane, and n-decane

    Science.gov (United States)

    He, Xin; Barthel, Anthony J.; Kim, Seong H.

    2016-06-01

    The mechanochemical reactions of adsorbed molecules at sliding interfaces were studied for α-pinene (C10H16), pinane (C10H18), and n-decane (C10H22) on a stainless steel substrate surface. During vapor phase lubrication, molecules adsorbed at the sliding interface could be activated by mechanical shear. Under the equilibrium adsorption condition of these molecules, the friction coefficient of sliding steel surfaces was about 0.2 and a polymeric film was tribochemically produced. The synthesis yield of α-pinene tribo-polymers was about twice as much as pinane tribo-polymers. In contrast to these strained bicyclic hydrocarbons, n-decane showed much weaker activity for tribo-polymerization at the same mechanical shear condition. These results suggested that the mechanical shear at tribological interfaces could induce the opening of the strained ring structure of α-pinene and pinane, which leads to polymerization of adsorbed molecules at the sliding track. On a stainless steel surface, such polymerization reactions of adsorbed molecules do not occur under typical surface reaction conditions. The mechanical properties and boundary lubrication efficiency of the produced tribo-polymer films are discussed.

  1. Modification of the electronic properties of Au/molecule/Pd junctions by adsorbed hydrogen: a DFT study

    Energy Technology Data Exchange (ETDEWEB)

    Kucera, Jan; Gross, Axel [Institut fuer Theoretische Chemie, Universitaet Ulm, D-89069 Ulm (Germany)

    2011-07-01

    Metal-molecule-metal contacts assembled from a Pd monolayer deposited on a Au-supported self-assembled monolayer (SAM) of 4-mercaptopyridine or 4-aminothiophenol were recently achieved by means of an electrochemical approach. Subsequent photoelectron spectroscopy showed a strongly reduced Pd density of states (DOS) at the Fermi energy. This phenomenon is still not fully comprehended, however, its understanding is crucial for the use of the sandwich design as a platform for future nanoelectronics. Periodic density functional theory (DFT) calculation revealed that the dehydrogenation of the amino group and the subsequent strong bonding of the remaining nitrogen atom to the Pd layer could explain the observed modification of the DOS. We have now extended this study in order to clarify the role of hydrogen atoms for the electronic properties of the Pd layers. In equilibrium, these layers should always show a considerable hydrogen coverage in an aqueous environment. Our calculations demonstrate that indeed the adsorbed hydrogen atoms significantly modify the electronic structure of the Pd layers.

  2. Observation and analysis of Fano-like lineshapes in the Raman spectra of molecules adsorbed at metal interfaces

    Science.gov (United States)

    Dey, S.; Banik, M.; Hulkko, E.; Rodriguez, K.; Apkarian, V. A.; Galperin, M.; Nitzan, A.

    2016-01-01

    Surface-enhanced Raman scattering (SERS) from bipyridyl ethylene adsorbed on gold dumbbells shows Fano-like spectra at high incident light intensity. This is accompanied by an increased electronic temperature, while no vibrational anti-Stokes scattering is observed. Theory indicates that interference between vibrational and electronic Raman scattering can yield such asymmetric scattering lineshapes. The best fit to observations is however obtained by disregarding this coupling and accounting for the detailed lineshape of the continuous electronic component of the SERS.

  3. Multi-modal, ultrasensitive detection of trace explosives using MEMS devices with quantum cascade lasers

    Science.gov (United States)

    Zandieh, Omid; Kim, Seonghwan

    2016-05-01

    Multi-modal chemical sensors based on microelectromechanical systems (MEMS) have been developed with an electrical readout. Opto-calorimetric infrared (IR) spectroscopy, capable of obtaining molecular signatures of extremely small quantities of adsorbed explosive molecules, has been realized with a microthermometer/microheater device using a widely tunable quantum cascade laser. A microthermometer/microheater device responds to the heat generated by nonradiative decay process when the adsorbed explosive molecules are resonantly excited with IR light. Monitoring the variation in microthermometer signal as a function of illuminating IR wavelength corresponds to the conventional IR absorption spectrum of the adsorbed molecules. Moreover, the mass of the adsorbed molecules is determined by measuring the resonance frequency shift of the cantilever shape microthermometer for the quantitative opto-calorimetric IR spectroscopy. In addition, micro-differential thermal analysis, which can be used to differentiate exothermic or endothermic reaction of heated molecules, has been performed with the same device to provide additional orthogonal signal for trace explosive detection and sensor surface regeneration. In summary, we have designed, fabricated and tested microcantilever shape devices integrated with a microthermometer/microheater which can provide electrical responses used to acquire both opto-calorimetric IR spectra and microcalorimetric thermal responses. We have demonstrated the successful detection, differentiation, and quantification of trace amounts of explosive molecules and their mixtures (cyclotrimethylene trinitramine (RDX) and pentaerythritol tetranitrate (PETN)) using three orthogonal sensing signals which improve chemical selectivity.

  4. Surface-Enhanced Raman Spectroscopy of Dye and Thiol Molecules Adsorbed on Triangular Silver Nanostructures: A Study of Near-Field Enhancement, Localization of Hot-Spots, and Passivation of Adsorbed Carbonaceous Species

    Directory of Open Access Journals (Sweden)

    Manuel R. Gonçalves

    2012-01-01

    Full Text Available Surface-enhanced Raman spectroscopy (SERS of thiols and dye molecules adsorbed on triangular silver nanostructures was investigated. The SERS hot-spots are localized at the edges and corners of the silver triangular particles. AFM and SEM measurements permit to observe many small clusters formed at the edges of triangular particles fabricated by nanosphere lithography. Finite-element calculations show that near-field enhancements can reach values of more than 200 at visible wavelengths, in the gaps between small spherical particles and large triangular particles, although for the later no plasmon resonance was found at the wavelengths investigated. The regions near the particles showing strong near-field enhancement are well correlated with spatial localization of SERS hot-spots done by confocal microscopy. Silver nanostructures fabricated by thermal evaporation present strong and fast fluctuating SERS activity, due to amorphous carbon contamination. Thiols and dye molecules seem to be able to passivate the undesired SERS activity on fresh evaporated silver.

  5. Electron stimulated desorption of cations from C sub 6 H sub 6 and C sub 6 H sub 1 sub 2 molecules adsorbed on Pt(1 1 1) and Ar spacer layer

    CERN Document Server

    Kawanowa, H; Hanatani, K; Gotoh, Y; Souda, R

    2003-01-01

    Mechanisms of electron stimulated cation desorption have been investigated for adsorbed C sub 6 H sub 6 and C sub 6 H sub 1 sub 2 molecules on the Pt(1 1 1) surface and the Ar spacer layer formed on it. The ion yields from the molecules adsorbed on the Ar spacer layer are highly enhanced at the smallest coverage and decay steeply with increasing coverage. No such enhancement was observed when they are adsorbed directly on the Pt(1 1 1) substrate. This behavior is explained in terms of the Coulombic repulsion of cations confined in nanoclusters, together with the delocalization of valence holes on the Pt(1 1 1) substrate as well as in the multilayer hydrocarbons. The holes in the C sub 6 H sub 6 molecule are more delocalized than those in the C sub 6 H sub 1 sub 2 molecule due to the overlap of pi orbitals.

  6. Metal-free phthalocyanine (H2Pc molecule adsorbed on the Au(111 surface: formation of a wide domain along a single lattice direction

    Directory of Open Access Journals (Sweden)

    Tadahiro Komeda, Hironari Isshiki and Jie Liu

    2010-01-01

    Full Text Available Using low-temperature scanning tunneling microscopy (STM, we observed the bonding configuration of the metal-free phthalocyanine (H2Pc molecule adsorbed on the Au(111 surface. A local lattice formation started from a quasi-square lattice aligned to the close-packed directions of the Au(111 surface. Although we expected the lattice alignment to be equally distributed along the three crystallographically equivalent directions, the domain aligned normal to the ridge of the herringbone structure was missing in the STM images. We attribute this effect to the uniaxial contraction of the reconstructed Au(111 surface that can account for the formation of a large lattice domain along a single crystallographical direction.

  7. Transfer of chirality from adsorbed chiral molecules to the substrates highlighted by circular dichroism in angle-resolved valence photoelectron spectroscopy

    DEFF Research Database (Denmark)

    Contini, G.; Turchini, S.; Sanna, Simone;

    2012-01-01

    state, that the presence of molecular chiral domains induces asymmetry in the interaction with the substrate and locally transfers the chiral character to the underlying metal atoms participating in the adsorption process; combined information related to the asymmetry of the initial electronic state......Studies of self-assembled chiral molecules on achiral metallic surfaces have mostly focused on the determination of the geometry of adsorbates and their electronic structure. The aim of this paper is to provide direct information on the chirality character of the system and on the chirality......, which is expected to be chiral, and the final electronic state, which locally probes the asymmetry of the potential, has been obtained. Identification of chirality in the adsorption footprint sheds new light on the transfer of chirality from a chiral modifier to a symmetric metal surface and represents...

  8. David Adler Lectureship Award Talk: Friction and energy dissipation mechanisms in adsorbed molecules and molecularly thin films

    Science.gov (United States)

    Krim, Jacqueline

    2015-03-01

    Studies of the fundamental origins of friction have undergone rapid progress in recent years, with the development of new experimental and computational techniques for measuring and simulating friction at atomic length and time scales. The increased interest has sparked a variety of discussions and debates concerning the nature of the atomic-scale and quantum mechanisms that dominate the dissipative process by which mechanical energy is transformed into heat. Measurements of the sliding friction of physisorbed monolayers and bilayers can provide information on the relative contributions of these various dissipative mechanisms. Adsorbed films, whether intentionally applied or present as trace levels of physisorbed contaminants, moreover are ubiquitous at virtually all surfaces. As such, they impact a wide range of applications whose progress depends on precise control and/or knowledge of surface diffusion processes. Examples include nanoscale assembly, directed transport of Brownian particles, material flow through restricted geometries such as graphene membranes and molecular sieves, passivation and edge effects in carbon-based lubricants, and the stability of granular materials associated with frictional and frictionless contacts. Work supported by NSFDMR1310456.

  9. On the widths of Stokes lines in Raman scattering from molecules adsorbed at metal surfaces and in molecular conduction junctions

    Science.gov (United States)

    Gao, Yi; Galperin, Michael; Nitzan, Abraham

    2016-06-01

    Within a generic model we analyze the Stokes linewidth in surface enhanced Raman scattering (SERS) from molecules embedded as bridges in molecular junctions. We identify four main contributions to the off-resonant Stokes signal and show that under zero voltage bias (a situation pertaining also to standard SERS experiments) and at low bias junctions only one of these contributions is pronounced. The linewidth of this component is determined by the molecular vibrational relaxation rate, which is dominated by interactions with the essentially bosonic thermal environment when the relevant molecular electronic energy is far from the metal(s) Fermi energy(ies). It increases when the molecular electronic level is close to the metal Fermi level so that an additional vibrational relaxation channel due to electron-hole (eh) exciton in the molecule opens. Other contributions to the Raman signal, of considerably broader linewidths, can become important at larger junction bias.

  10. Multidimensional detection of explosives and explosive signatures via laser electrospray mass spectrometry

    Science.gov (United States)

    Brady, John J.; Flanigan, Paul M., IV; Perez, Johnny J.; Judge, Elizabeth J.; Levis, Robert J.

    2012-06-01

    Nitro- and inorganic-based energetic material is vaporized at atmospheric pressure using nonresonant, 70 femtosecond laser pulses prior to electrospray post-ionization and transfer into a time-of-flight mass spectrometer for mass analysis. Measurements of a nitro-based energetic molecule, cyclotrimethylenetrinitramine (RDX), adsorbed on metal and dielectric surfaces indicate nonresonant vaporization of intact molecules, demonstrating the universality of laser electrospray mass spectrometry (LEMS) technique for explosives. In addition, RDX is analyzed at a distance of 2 meters to demonstrate the remote detection capability of LEMS. Finally, the analysis and multivariate statistical classification of inorganic-based explosives containing ammonium nitrate, chlorate, perchlorate, black powder, and an organic-based explosive is presented, further expanding the capabilities of the LEMS technique for detection of energetic materials.

  11. Performance of the TPSS Functional on Predicting Core Level Binding Energies of Main Group Elements Containing Molecules: A Good Choice for Molecules Adsorbed on Metal Surfaces.

    Science.gov (United States)

    Pueyo Bellafont, Noèlia; Viñes, Francesc; Illas, Francesc

    2016-01-12

    Here we explored the performance of Hartree-Fock (HF), Perdew-Burke-Ernzerhof (PBE), and Tao-Perdew-Staroverov-Scuseria (TPSS) functionals in predicting core level 1s binding energies (BEs) and BE shifts (ΔBEs) for a large set of 68 molecules containing a wide variety of functional groups for main group elements B → F and considering up to 185 core levels. A statistical analysis comparing with X-ray photoelectron spectroscopy (XPS) experiments shows that BEs estimations are very accurate, TPSS exhibiting the best performance. Considering ΔBEs, the three methods yield very similar and excellent results, with mean absolute deviations of ∼0.25 eV. When considering relativistic effects, BEs deviations drop approaching experimental values. So, the largest mean percentage deviation is of 0.25% only. Linear trends among experimental and estimated values have been found, gaining offsets with respect to ideality. By adding relativistic effects to offsets, HF and TPSS methods underestimate experimental values by solely 0.11 and 0.05 eV, respectively, well within XPS chemical precision. TPSS is posed as an excellent choice for the characterization, by XPS, of molecules on metal solid substrates, given its suitability in describing metal substrates bonds and atomic and/or molecular orbitals.

  12. Optical and electronic properties of SO2 molecule adsorbed on Si-doped (8, 0) boron nitride nanotube

    Science.gov (United States)

    Guo, Shuang-Shuang; Wei, Xiu-Mei; Zhang, Jian-Min; Zhu, Gang-Qiang; Guo, Wan-Jin

    2016-09-01

    The study of the optical properties of pristine BNNT, Si-doped BNNTs and SO2 molecule adsorption on Si-doped BNNTs is that, to our knowledge, few relevant research have ever been found. In this paper, the adsorption behaviors of Sulfur dioxide (SO2) molecule on Si-doped Boron nitride nanotubes (BNNTs) are investigated applying the first-principles calculations. The main contribution of this paper is that the foremost investigation for the optical properties of the pristine BNNT, Si-doped BNNTs and SO2 adsorption on Si-doped BNNTs. Additionally, the electronic properties and the structural properties are also presented. In our calculations of optical properties, the dielectric constant, the refractive index and the absorption coefficient are obtained. Comparing the pristine BNNT, our results indicate that, the blue-shifts (in the main peaks of the dielectric constant of SiB -BNNT and SO2-SiB -BNNT), and the red-shifts (in the main peaks of the refractive index of SiN -BNNT and SO2-SiN -BNNT) are appeared. Under these conditions, Si-doped BNNT and Si-doped BNNT with SO2 adsorption, the gaps are reduced both for the speculated optical band gaps and the electronic structure band gaps.

  13. Expansion Hamiltonian model for a diatomic molecule adsorbed on a surface: Vibrational states of the CO/Cu(100) system including surface vibrations

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Qingyong, E-mail: mengqingyong@dicp.ac.cn [State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Zhongshan Road 457, 116023 Dalian (China); Meyer, Hans-Dieter, E-mail: hans-dieter.meyer@pci.uni-heidelberg.de [Theoretische Chemie, Physikalisch-Chemisches Institut, Ruprecht-Karls Universität Heidelberg, Im Neuenheimer Feld 229, D-69120 Heidelberg (Germany)

    2015-10-28

    Molecular-surface studies are often done by assuming a corrugated, static (i.e., rigid) surface. To be able to investigate the effects that vibrations of surface atoms may have on spectra and cross sections, an expansion Hamiltonian model is proposed on the basis of the recently reported [R. Marquardt et al., J. Chem. Phys. 132, 074108 (2010)] SAP potential energy surface (PES), which was built for the CO/Cu(100) system with a rigid surface. In contrast to other molecule-surface coupling models, such as the modified surface oscillator model, the coupling between the adsorbed molecule and the surface atoms is already included in the present expansion SAP-PES model, in which a Taylor expansion around the equilibrium positions of the surface atoms is performed. To test the quality of the Taylor expansion, a direct model, that is avoiding the expansion, is also studied. The latter, however, requests that there is only one movable surface atom included. On the basis of the present expansion and direct models, the effects of a moving top copper atom (the one to which CO is bound) on the energy levels of a bound CO/Cu(100) system are studied. For this purpose, the multiconfiguration time-dependent Hartree calculations are carried out to obtain the vibrational fundamentals and overtones of the CO/Cu(100) system including a movable top copper atom. In order to interpret the results, a simple model consisting of two coupled harmonic oscillators is introduced. From these calculations, the vibrational levels of the CO/Cu(100) system as function of the frequency of the top copper atom are discussed.

  14. Expansion Hamiltonian model for a diatomic molecule adsorbed on a surface: Vibrational states of the CO/Cu(100) system including surface vibrations

    International Nuclear Information System (INIS)

    Molecular-surface studies are often done by assuming a corrugated, static (i.e., rigid) surface. To be able to investigate the effects that vibrations of surface atoms may have on spectra and cross sections, an expansion Hamiltonian model is proposed on the basis of the recently reported [R. Marquardt et al., J. Chem. Phys. 132, 074108 (2010)] SAP potential energy surface (PES), which was built for the CO/Cu(100) system with a rigid surface. In contrast to other molecule-surface coupling models, such as the modified surface oscillator model, the coupling between the adsorbed molecule and the surface atoms is already included in the present expansion SAP-PES model, in which a Taylor expansion around the equilibrium positions of the surface atoms is performed. To test the quality of the Taylor expansion, a direct model, that is avoiding the expansion, is also studied. The latter, however, requests that there is only one movable surface atom included. On the basis of the present expansion and direct models, the effects of a moving top copper atom (the one to which CO is bound) on the energy levels of a bound CO/Cu(100) system are studied. For this purpose, the multiconfiguration time-dependent Hartree calculations are carried out to obtain the vibrational fundamentals and overtones of the CO/Cu(100) system including a movable top copper atom. In order to interpret the results, a simple model consisting of two coupled harmonic oscillators is introduced. From these calculations, the vibrational levels of the CO/Cu(100) system as function of the frequency of the top copper atom are discussed

  15. Enhanced binding capacity of boronate affinity adsorbent via surface modification of silica by combination of atom transfer radical polymerization and chain-end functionalization for high-efficiency enrichment of cis-diol molecules

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wei; He, Maofang; Wang, Chaozhan; Wei, Yinmao, E-mail: ymwei@nwu.edu.cn

    2015-07-30

    Boronate affinity materials have been widely used for specific separation and preconcentration of cis-diol molecules, but most do not have sufficient capacity due to limited binding sites on the material surface. In this work, we prepared a phenylboronic acid-functionalized adsorbent with a high binding capacity via the combination of surface-initiated atom transfer radical polymerization (SI-ATRP) and chain-end functionalization. With this method, the terminal chlorides of the polymer chains were used fully, and the proposed adsorbent contains dense boronic acid polymers chain with boronic acid on the chain end. Consequently, the proposed adsorbent possesses excellent selectivity and a high binding capacity of 513.6 μmol g{sup −1} for catechol and 736.8 μmol g{sup −1} for fructose, which are much higher than those of other reported adsorbents. The dispersed solid-phase extraction (dSPE) based on the prepared adsorbent was used for extraction of three cis-diol drugs (i.e., epinephrine, isoprenaline and caffeic acid isopropyl ester) from plasma; the eluates were analyzed by HPLC-UV. The reduced amount of adsorbent (i.e., 2.0 mg) could still eliminate interferences efficiently and yielded a recovery range of 85.6–101.1% with relative standard deviations ranging from 2.5 to 9.7% (n = 5). The results indicated that the proposed strategy could serve as a promising alternative to increase the density of surface functional groups on the adsorbent; thus, the prepared adsorbent has the potential to effectively enrich cis-diol substances in real samples. - Highlights: • Boronate adsorbent is prepared via ATRP and chain-end functionalization. • The adsorbent has quite high binding capacity for cis-diols. • Binding capacity is easily manipulated by ATRP condition. • Chain-end functionalization can improve binding capacity significantly. • Reduced adsorbent is consumed in dispersed solid-phase extraction of cis-diols.

  16. Adsorption and trace detection of pharmacologically significant 5-methylthio-1, 3, 4-thiadiazole-2-thiol molecule adsorbed on silver nanocolloids and understanding the role of Albrecht's “A” and Herzberg-Teller contributions in the SERS spectra

    Science.gov (United States)

    Chowdhury, Joydeep; Chandra, Subhendu; Ghosh, Manash

    2015-01-01

    The surface enhanced Raman scattering (SERS) spectra of biologically and industrially significant 5-methylthio-1, 3, 4-thiadiazole 2-thiol molecule have been investigated. The SERS spectra at various concentrations of the adsorbate are compared with the Fourier transform Infrared (FTIR) and normal Raman spectra (NRS) of the probe molecule recorded in different environmental conditions. The optimized molecular structures of the most probable thione and the thiol forms of the molecule have been estimated from the density functional theory (DFT) calculations. The vibrational signatures of the molecule have been assigned from the potential energy distributions (PEDs). The detail vibrational analyses reveal that ∼54% of the thione form of the molecule is prevalent in the solid state and its population increases to ∼65% in ACN solvent medium. Concentration dependent SERS, together with the 2-dimensional correlation spectra (2D-COS), corroborate the presence of both the thione and the thiol forms of the molecule even in the surface adsorbed state. The orientations of the thione and the thiol forms of the molecule on the nanocolloidal silver surface have been predicted from the surface selection rule. The selective enhancement of Raman bands in the SERS spectra have been explored from the view of the Albrecht's "A" and Herzberg-Teller (HT) charge transfer (CT) contribution.

  17. Chemical sensing system for classification of mine-like objects by explosives detection

    Energy Technology Data Exchange (ETDEWEB)

    Chambers, W.B.; Rodacy, P.J.; Jones, E.E.; Gomez, B.J.; Woodfin, R.L.

    1998-04-01

    Sandia National Laboratories has conducted research in chemical sensing and analysis of explosives for many years. Recently, that experience has been directed towards detecting mines and unexploded ordnance (UXO) by sensing the low-level explosive signatures associated with these objects. The authors focus has been on the classification of UXO in shallow water and anti-personnel/anti tank mines on land. The objective of this work is to develop a field portable chemical sensing system which can be used to examine mine-like objects (MLO) to determine whether there are explosive molecules associated with the MLO. Two sampling subsystems have been designed, one for water collection and one for soil/vapor sampling. The water sampler utilizes a flow-through chemical adsorbent canister to extract and concentrate the explosive molecules. Explosive molecules are thermally desorbed from the concentrator and trapped in a focusing stage for rapid desorption into an ion-mobility spectrometer (IMS). The authors describe a prototype system which consists of a sampler, concentrator-focuser, and detector. The soil sampler employs a light-weight probe for extracting and concentrating explosive vapor from the soil in the vicinity of an MLO. The chemical sensing system is capable of sub-part-per-billion detection of TNT and related explosive munition compounds. They present the results of field and laboratory tests on buried landmines which demonstrate their ability to detect the explosive signatures associated with these objects.

  18. Extending the range of low energy electron diffraction (LEED) surface structure determination: Co-adsorbed molecules, incommensurate overlayers and alloy surface order studied by new video and electron counting LEED techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ogletree, D.F.

    1986-11-01

    LEED multiple scattering theory is briefly summarized, and aspects of electron scattering with particular significance to experimental measurements such as electron beam coherence, instrument response and phonon scattering are analyzed. Diffuse LEED experiments are discussed. New techniques that enhance the power of LEED are described, including a real-time video image digitizer applied to LEED intensity measurements, along with computer programs to generate I-V curves. The first electron counting LEED detector using a ''wedge and strip'' position sensitive anode and digital electronics is described. This instrument uses picoampere incident beam currents, and its sensitivity is limited only by statistics and counting times. Structural results on new classes of surface systems are presented. The structure of the c(4 x 2) phase of carbon monoxide adsorbed on Pt(111) has been determined, showing that carbon monoxide molecules adsorb in both top and bridge sites, 1.85 +- 0.10 A and 1.55 +- 0.10 A above the metal surface, respectively. The structure of an incommensurate graphite overlayer on Pt(111) is analyzed. The graphite layer is 3.70 +- 0.05 A above the metal surface, with intercalated carbon atoms located 1.25 +- 0.10 A above hollow sites supporting it. The (2..sqrt..3 x 4)-rectangular phase of benzene and carbon monoxide coadsorbed on Pt(111) is analyzed. Benzene molecules adsorb in bridge sites parallel to and 2.10 +- 0.10 A above the surface. The carbon ring is expanded, with an average C-C bond length of 1.72 +- 0.15 A. The carbon monoxide molecules also adsorb in bridge sites. The structure of the (..sqrt..3 x ..sqrt..3) reconstruction on the (111) face of the ..cap alpha..-CuAl alloy has been determined.

  19. Extending the range of low energy electron diffraction (LEED) surface structure determination: Co-adsorbed molecules, incommensurate overlayers and alloy surface order studied by new video and electron counting LEED techniques

    International Nuclear Information System (INIS)

    LEED multiple scattering theory is briefly summarized, and aspects of electron scattering with particular significance to experimental measurements such as electron beam coherence, instrument response and phonon scattering are analyzed. Diffuse LEED experiments are discussed. New techniques that enhance the power of LEED are described, including a real-time video image digitizer applied to LEED intensity measurements, along with computer programs to generate I-V curves. The first electron counting LEED detector using a ''wedge and strip'' position sensitive anode and digital electronics is described. This instrument uses picoampere incident beam currents, and its sensitivity is limited only by statistics and counting times. Structural results on new classes of surface systems are presented. The structure of the c(4 x 2) phase of carbon monoxide adsorbed on Pt(111) has been determined, showing that carbon monoxide molecules adsorb in both top and bridge sites, 1.85 +- 0.10 A and 1.55 +- 0.10 A above the metal surface, respectively. The structure of an incommensurate graphite overlayer on Pt(111) is analyzed. The graphite layer is 3.70 +- 0.05 A above the metal surface, with intercalated carbon atoms located 1.25 +- 0.10 A above hollow sites supporting it. The (2√3 x 4)-rectangular phase of benzene and carbon monoxide coadsorbed on Pt(111) is analyzed. Benzene molecules adsorb in bridge sites parallel to and 2.10 +- 0.10 A above the surface. The carbon ring is expanded, with an average C-C bond length of 1.72 +- 0.15 A. The carbon monoxide molecules also adsorb in bridge sites. The structure of the (√3 x √3) reconstruction on the (111) face of the α-CuAl alloy has been determined

  20. Research topics in explosives - a look at explosives behaviors

    International Nuclear Information System (INIS)

    The behaviors of explosives under many conditions - e.g., sensitivity to inadvertent reactions, explosion, detonation - are controlled by the chemical and physical properties of the explosive materials. Several properties are considered for a range of improvised and conventional explosives. Here I compare these properties across a wide range of explosives to develop an understanding of explosive behaviors. For improvised explosives, which are generally heterogeneous mixtures of ingredients, a range of studies is identified as needed to more fully understand their behavior and properties. For conventional explosives, which are generally comprised of crystalline explosive molecules held together with a binder, I identify key material properties that determine overall sensitivity, including the extremely safe behavior of Insensitive High Explosives, and discuss an approach to predicting the sensitivity or insensitivity of an explosive.

  1. Targeted adsorption of molecules in the colon with the novel adsorbent-based medicinal product, DAV132: A proof of concept study in healthy subjects.

    Science.gov (United States)

    de Gunzburg, Jean; Ducher, Annie; Modess, Christiane; Wegner, Danilo; Oswald, Stefan; Dressman, Jennifer; Augustin, Violaine; Feger, Céline; Andremont, Antoine; Weitschies, Werner; Siegmund, Werner

    2015-01-01

    During antibiotic treatments, active residuals reaching the colon profoundly affect the bacterial flora resulting in the emergence of resistance. To prevent these effects, we developed an enteric-coated formulated activated-charcoal based product, DAV132, meant to deliver its adsorbent to the ileum and neutralize antibiotic residues in the proximal colon. In a randomized, control, crossover study, the plasma pharmacokinetics of the probe drugs amoxicillin (500 mg) absorbed in the proximal intestine, and sulfapyridine (25 mg) metabolized from sulfasalazine in the cecum and rapidly absorbed, were compared after a single administration in 18 healthy subjects who had received DAV132, uncoated formulated activated charcoal (FAC) or water 16 and 8 hours before, concomitantly with the probe drugs, and 8 hours thereafter. The AUC0-96 h of amoxicillin was reduced by more than 70% when it was taken with FAC, but bioequivalent when it was taken with water or DAV132. By contrast, the AUC0-96 h of sulfapyridine was reduced by more than 90% when administered with either FAC or DAV132 in comparison with water. The results show that DAV132 can selectively adsorb drug compounds in the proximal colon, without interfering with drug absorption in the proximal small intestine, thereby constituting a proof of concept that DAV132 actually functions in humans.

  2. Scanning tunneling microscopy theory for an adsorbate: Application to adenine adsorbed on a graphite surface

    OpenAIRE

    Ou-Yang, Hui; Marcus, R. A.; Källebring, Bruno

    1994-01-01

    An expression is obtained for the current in scanning tunneling microscopy (STM) for a single adsorbate molecule. For this purpose the ``Newns–Anderson'' treatment (a ``discrete state in a continuum'' treatment) is used to obtain wave functions and other properties of the adsorbate/substrate system. The current is expressed in terms of the adsorbate–tip matrix elements, and an effective local density of states of the adsorbate/substrate system, at the adsorbate. As an example, the treatment i...

  3. Heterogeneous catalytic processes on cobalt, molybdenum and cobalt-molybdenum catalysts studied by temperature-programmed desorption and temperature-programmed reaction. 27 H-D exchange between adsorbed hydrogen and various coadsorbed molecules on the surface of Co-Mo catalysts

    International Nuclear Information System (INIS)

    The H-D-exchange between hydrogen adsorbed on the surface of reduced catalyst Co-Mo/Al2O3 and molecules of coadsorbates: D2O, benzene C6D6, cyclohexane C6D12 and propanethiol C3H7SH, has been studied under conditions of temperature-programmed reaction. It has been discovered that al the forms of hydrogen adsorbed on the catalyst take part in H-D-exchange. Spillover hydrogen adsorbed on a substrate features a high degree of Y-D-exchange with the coadsorbates mentioned. 2 refs., 6 figs

  4. NEXAF/XPS study of organic molecules adsorbed on rutile TiO2(110) and Al2O3/ Ni3Al(111) substrates

    OpenAIRE

    Naboka, Michael

    2014-01-01

    The spectroscopic studies of metal oxide surface interaction with different organic molecules have been performed for the needs of organic electronics, heterogeneous catalysis and surface chemistry. Three different systems: terephthalic acid (TPA) on rutile TiO2(110), azobenzene on rutile-TiO2(110), and tetracene on Al2O3/Ni3Al (111) were investigated.

  5. Role of intermolecular interactions on the electronic and geometric structure of a large Pi-conjugated molecule adsorbed on a metal surface

    OpenAIRE

    Kilian, L.; Hauschild, A.; Temirov, R.; Soubatch, S.; Schoell, A.; Bendounan, A.; Reinert, F.; Lee, T. L.; Tautz, F. S.; Sokolowski, M.; Umbach, E

    2008-01-01

    The organic semiconductor molecule 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) exhibits two adsorption states on the Ag(111) surface: one in a metastable disordered phase, prepared at low temperatures, the other in the long-range ordered monolayer phase obtained at room temperature. Notably, the two states differ substantial in their vertical bonding distances, intramolecular distortions, and electronic structures. The difference is explained by intermolecular interactions, which ar...

  6. Primary explosives

    Energy Technology Data Exchange (ETDEWEB)

    Matyas, Robert; Pachman, Jiri [Pardubice Univ. (Czech Republic). Faculty of Chemical Technology

    2013-06-01

    The first chapter provides background such as the basics of initiation and differences between requirements on primary explosives used in detonators and igniters. The authors then clarify the influence of physical characteristics on explosive properties, focusing on those properties required for primary explosives. Furthermore, the issue of sensitivity is discussed. All the chapters on particular groups of primary explosives are structured in the same way, including introduction, physical and chemical properties, explosive properties, preparation and documented use.

  7. Nanovalved Adsorbents for CH4 Storage.

    Science.gov (United States)

    Song, Zhuonan; Nambo, Apolo; Tate, Kirby L; Bao, Ainan; Zhu, Minqi; Jasinski, Jacek B; Zhou, Shaojun J; Meyer, Howard S; Carreon, Moises A; Li, Shiguang; Yu, Miao

    2016-05-11

    A novel concept of utilizing nanoporous coatings as effective nanovalves on microporous adsorbents was developed for high capacity natural gas storage at low storage pressure. The work reported here for the first time presents the concept of nanovalved adsorbents capable of sealing high pressure CH4 inside the adsorbents and storing it at low pressure. Traditional natural gas storage tanks are thick and heavy, which makes them expensive to manufacture and highly energy-consuming to carry around. Our design uses unique adsorbent pellets with nanoscale pores surrounded by a coating that functions as a valve to help manage the pressure of the gas and facilitate more efficient storage and transportation. We expect this new concept will result in a lighter, more affordable product with increased storage capacity. The nanovalved adsorbent concept demonstrated here can be potentially extended for the storage of other important gas molecules targeted for diverse relevant functional applications. PMID:27124722

  8. The Dynamics and Structures of Adsorbed Surfaces

    DEFF Research Database (Denmark)

    Nielsen, M; Ellenson, W. D.; McTague, J. P.

    1978-01-01

    Reviews neutron scattering work performed on films of simple gas atoms and molecules adsorbed primarily on graphite surfaces. Exfoliated graphite substrates such as Grafoil were first used in this kind of measurements about five years ago and new results have been reported at an increasing pace. ...

  9. Explosive laser

    International Nuclear Information System (INIS)

    This patent relates to a laser system wherein reaction products from the detonation of a condensed explosive expand to form a gaseous medium with low translational temperature but high vibration population. Thermal pumping of the upper laser level and de-excitation of the lower laser level occur during the expansion, resulting in a population inversion. The expansion may be free or through a nozzle as in a gas-dynamic configuration. In one preferred embodiment, the explosive is such that its reaction products are CO2 and other species that are beneficial or at least benign to CO2 lasing

  10. Studies of the laser-induced fluorescence of explosives and explosive compositions.

    Energy Technology Data Exchange (ETDEWEB)

    Hargis, Philip Joseph, Jr. (,; .); Thorne, Lawrence R.; Phifer, Carol Celeste; Parmeter, John Ethan; Schmitt, Randal L.

    2006-10-01

    Continuing use of explosives by terrorists throughout the world has led to great interest in explosives detection technology, especially in technologies that have potential for standoff detection. This LDRD was undertaken in order to investigate the possible detection of explosive particulates at safe standoff distances in an attempt to identify vehicles that might contain large vehicle bombs (LVBs). The explosives investigated have included the common homogeneous or molecular explosives, 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), cyclonite or hexogen (RDX), octogen (HMX), and the heterogeneous explosive, ammonium nitrate/fuel oil (ANFO), and its components. We have investigated standard excited/dispersed fluorescence, laser-excited prompt and delayed dispersed fluorescence using excitation wavelengths of 266 and 355 nm, the effects of polarization of the laser excitation light, and fluorescence imaging microscopy using 365- and 470-nm excitation. The four nitro-based, homogeneous explosives (TNT, PETN, RDX, and HMX) exhibit virtually no native fluorescence, but do exhibit quenching effects of varying magnitude when adsorbed on fluorescing surfaces. Ammonium nitrate and fuel oil mixtures fluoresce primarily due to the fuel oil, and, in some cases, due to the presence of hydrophobic coatings on ammonium nitrate prill or impurities in the ammonium nitrate itself. Pure ammonium nitrate shows no detectable fluorescence. These results are of scientific interest, but they provide little hope for the use of UV-excited fluorescence as a technique to perform safe standoff detection of adsorbed explosive particulates under real-world conditions with a useful degree of reliability.

  11. Explosive complexes

    Science.gov (United States)

    Huynh, My Hang V.

    2009-09-22

    Lead-free primary explosives of the formula [M.sup.II(A).sub.R(B.sup.X).sub.S](C.sup.Y).sub.T, where A is 1,5-diaminotetrazole, and syntheses thereof are described. Substantially stoichiometric equivalents of the reactants lead to high yields of pure compositions thereby avoiding dangerous purification steps.

  12. Niche explosion.

    Science.gov (United States)

    Normark, Benjamin B; Johnson, Norman A

    2011-05-01

    The following syndrome of features occurs in several groups of phytophagous insects: (1) wingless females, (2) dispersal by larvae, (3) woody hosts, (4) extreme polyphagy, (5) high abundance, resulting in status as economic pests, (6) invasiveness, and (7) obligate parthenogenesis in some populations. If extreme polyphagy is defined as feeding on 20 or more families of hostplants, this syndrome is found convergently in several species of bagworm moths, tussock moths, root weevils, and 5 families of scale insects. We hypothesize that extreme polyphagy in these taxa results from "niche explosion", a positive feedback loop connecting large population size to broad host range. The niche explosion has a demographic component (sometimes called the "amplification effect" in studies of pathogens) as well as a population-genetic component, due mainly to the increased effectiveness of natural selection in larger populations. The frequent origins of parthenogenesis in extreme polyphages are, in our interpretation, a consequence of this increased effectiveness of natural selection and consequent reduced importance of sexuality. The niche explosion hypothesis makes detailed predictions about the comparative genomics and population genetics of extreme polyphages and related specialists. It has a number of potentially important implications, including an explanation for the lack of observed trade-offs between generalists and specialists, a re-interpretation of the ecological correlates of parthenogenesis, and a general expectation that Malthusian population explosions may be amplified by Darwinian effects.

  13. Molecular Adsorber Coating

    Science.gov (United States)

    Straka, Sharon; Peters, Wanda; Hasegawa, Mark; Hedgeland, Randy; Petro, John; Novo-Gradac, Kevin; Wong, Alfred; Triolo, Jack; Miller, Cory

    2011-01-01

    A document discusses a zeolite-based sprayable molecular adsorber coating that has been developed to alleviate the size and weight issues of current ceramic puck-based technology, while providing a configuration that more projects can use to protect against degradation from outgassed materials within a spacecraft, particularly contamination-sensitive instruments. This coating system demonstrates five times the adsorption capacity of previously developed adsorber coating slurries. The molecular adsorber formulation was developed and refined, and a procedure for spray application was developed. Samples were spray-coated and tested for capacity, thermal optical/radiative properties, coating adhesion, and thermal cycling. Work performed during this study indicates that the molecular adsorber formulation can be applied to aluminum, stainless steel, or other metal substrates that can accept silicate-based coatings. The coating can also function as a thermal- control coating. This adsorber will dramatically reduce the mass and volume restrictions, and is less expensive than the currently used molecular adsorber puck design.

  14. Structure and properties of water film adsorbed on mica surfaces

    Science.gov (United States)

    Zhao, Gutian; Tan, Qiyan; Xiang, Li; Cai, Di; Zeng, Hongbo; Yi, Hong; Ni, Zhonghua; Chen, Yunfei

    2015-09-01

    The structure profiles and physical properties of the adsorbed water film on a mica surface under conditions with different degrees of relative humidity are investigated by a surface force apparatus. The first layer of the adsorbed water film shows ice-like properties, including a lattice constant similar with ice crystal, a high bearing capacity that can support normal pressure as high as 4 MPa, a creep behavior under the action of even a small normal load, and a character of hydrogen bond. Adjacent to the first layer of the adsorbed water film, the water molecules in the outer layer are liquid-like that can flow freely under the action of external loads. Experimental results demonstrate that the adsorbed water layer makes the mica surface change from hydrophilic to weak hydrophobic. The weak hydrophobic surface may induce the latter adsorbed water molecules to form water islands on a mica sheet.

  15. Structure and properties of water film adsorbed on mica surfaces.

    Science.gov (United States)

    Zhao, Gutian; Tan, Qiyan; Xiang, Li; Cai, Di; Zeng, Hongbo; Yi, Hong; Ni, Zhonghua; Chen, Yunfei

    2015-09-14

    The structure profiles and physical properties of the adsorbed water film on a mica surface under conditions with different degrees of relative humidity are investigated by a surface force apparatus. The first layer of the adsorbed water film shows ice-like properties, including a lattice constant similar with ice crystal, a high bearing capacity that can support normal pressure as high as 4 MPa, a creep behavior under the action of even a small normal load, and a character of hydrogen bond. Adjacent to the first layer of the adsorbed water film, the water molecules in the outer layer are liquid-like that can flow freely under the action of external loads. Experimental results demonstrate that the adsorbed water layer makes the mica surface change from hydrophilic to weak hydrophobic. The weak hydrophobic surface may induce the latter adsorbed water molecules to form water islands on a mica sheet.

  16. A theoretical study of adsorbate-adsorbate interactions on Ru(0001)

    DEFF Research Database (Denmark)

    Mortensen, Jens Jørgen; Hammer, Bjørk; Nørskov, Jens Kehlet

    1998-01-01

    Using density functional theory we study the effect of pre-adsorbed atoms on the dissociation of N(2) and the adsorption of N, N(2), and CO on Ru(0001). We have done calculations for pre-adsorbed Na, Cs, and S, and find that alkali atoms adsorbed close to a dissociating N(2) molecule will lower...... the barrier for dissociation, whereas S will increase it. The interaction with alkali atoms is mainly of an electrostatic nature. The poisoning by S is due to two kinds of repulsive interactions: a Pauli repulsion and a reduced covalent bond strength between the adsorbate and the surface d-electrons. In order...... to investigate these different interactions in more detail, we look at three different species (N atoms, and terminally bonded N(2) and CO) and use them as probes to study their interaction with two modifier atoms (Na and S). The two modifier atoms have very different properties, which allows us to decouple...

  17. Recent Advances in the Synthesis of High Explosive Materials

    OpenAIRE

    Jesse J. Sabatini; Karl D. Oyler

    2015-01-01

    This review discusses the recent advances in the syntheses of high explosive energetic materials. Syntheses of some relevant modern primary explosives and secondary high explosives, and the sensitivities and properties of these molecules are provided. In addition to the synthesis of such materials, processing improvement and formulating aspects using these ingredients, where applicable, are discussed in detail.

  18. Recent Advances in the Synthesis of High Explosive Materials

    Directory of Open Access Journals (Sweden)

    Jesse J. Sabatini

    2015-12-01

    Full Text Available This review discusses the recent advances in the syntheses of high explosive energetic materials. Syntheses of some relevant modern primary explosives and secondary high explosives, and the sensitivities and properties of these molecules are provided. In addition to the synthesis of such materials, processing improvement and formulating aspects using these ingredients, where applicable, are discussed in detail.

  19. 78 FR 64246 - Commerce in Explosives; List of Explosives Materials

    Science.gov (United States)

    2013-10-28

    ... isomorphously substituted inorganic salts. *ANFO . Aromatic nitro-compound explosive mixtures. Azide explosives.... Explosive mixtures containing tetranitromethane (nitroform). Explosive nitro compounds of aromatic... polyhydric alcohol explosives. Nitric acid and a nitro aromatic compound explosive. Nitric acid...

  20. Photoprocess of molecules encapsulated in porous solids X: Photosensitization of zeolite-Y encapsulated tris(2,2'-bipyridine-nickel-(II)ion by phenosafranine adsorbed onto the external surface of the nanoporous host

    Indian Academy of Sciences (India)

    Karuppannan Senthil Kumar; Sudha T; Paramasivam Natarajan

    2014-07-01

    Tris-(2,2'-bipyridine)-nickel-(II) complex ion encapsulated by zeolite-Y host has been synthesized by ship-in-a-bottle method. Photosensitization of nickel(II) complex (Ni(bpy)$^{2+}_{3}$) in the zeolite host by surface adsorbed phenosafranine dye was investigated by time-resolved fluorescence and absorption spectral measurements. Formation of nickel (II)-complex in the super cage of the host was ascertained by XRD, FTIR, solidstate NMR, diffuse reflectance UV-visible absorption spectroscopic techniques and ICP-OES measurements. Phenosafranine dye adsorbed on the external surface of zeolite-Y shows a decrease in fluorescence intensity with increased loading of the nickel(II) complex in zeolite-Y. Time-resolved emission studies show two excited state lifetimes for the photoexcited phenosafranine dye. Average fluorescence lifetimes of the dye in this case do not change with increase in the loading of the nickel(II) complex. However, relative contribution of short lifetime component increases when the amount of encapsulated nickel(II) complex is increased. The zeolite-Y host containing only bipyridyl ligand shows a marked decrease in fluorescence intensity. Fluorescence lifetimes of the dye however do not change with increased loading of bipyridyl while relative contribution of short lifetime component increases with an increase in the loading of bipyridyl in the host. This observation is interpreted to be due to electron transfer from the excited state of phenosafranine dye to the bipyridine. Picosecond pump-probe investigations confirm that the photoinduced electron transfer occurs from the surfaceadsorbed phenosafranine in the excited state to the nickel(II) complex within zeolite-Y cavity and also to the Ni(bpy)$^{2+}_{3}$ complex in contact with the phenosafranine dye co-adsorbed on the external surface of the host.

  1. Black Molecular Adsorber Coatings for Spaceflight Applications

    Science.gov (United States)

    Abraham, Nithin Susan; Hasegawa, Mark Makoto; Straka, Sharon A.

    2014-01-01

    The molecular adsorber coating is a new technology that was developed to mitigate the risk of on-orbit molecular contamination on spaceflight missions. The application of this coating would be ideal near highly sensitive, interior surfaces and instruments that are negatively impacted by outgassed molecules from materials, such as plastics, adhesives, lubricants, epoxies, and other similar compounds. This current, sprayable paint technology is comprised of inorganic white materials made from highly porous zeolite. In addition to good adhesion performance, thermal stability, and adsorptive capability, the molecular adsorber coating offers favorable thermal control characteristics. However, low reflectivity properties, which are typically offered by black thermal control coatings, are desired for some spaceflight applications. For example, black coatings are used on interior surfaces, in particular, on instrument baffles for optical stray light control. Similarly, they are also used within light paths between optical systems, such as telescopes, to absorb light. Recent efforts have been made to transform the white molecular adsorber coating into a black coating with similar adsorptive properties. This result is achieved by optimizing the current formulation with black pigments, while still maintaining its adsorption capability for outgassing control. Different binder to pigment ratios, coating thicknesses, and spray application techniques were explored to develop a black version of the molecular adsorber coating. During the development process, coating performance and adsorption characteristics were studied. The preliminary work performed on black molecular adsorber coatings thus far is very promising. Continued development and testing is necessary for its use on future contamination sensitive spaceflight missions.

  2. Regenerative adsorbent heat pump

    Science.gov (United States)

    Jones, Jack A. (Inventor)

    1991-01-01

    A regenerative adsorbent heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system and at least a portion of the heat of adsorption. A series of at least four compressors containing an adsorbent is provided. A large amount of heat is transferred from compressor to compressor so that heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

  3. Computer simulations of adsorbed liquid crystal films

    Science.gov (United States)

    Wall, Greg D.; Cleaver, Douglas J.

    2003-01-01

    The structures adopted by adsorbed thin films of Gay-Berne particles in the presence of a coexisting vapour phase are investigated by molecular dynamics simulation. The films are adsorbed at a flat substrate which favours planar anchoring, whereas the nematic-vapour interface favours normal alignment. On cooling, a system with a high molecule-substrate interaction strength exhibits substrate-induced planar orientational ordering and considerable stratification is observed in the density profiles. In contrast, a system with weak molecule-substrate coupling adopts a director orientation orthogonal to the substrate plane, owing to the increased influence of the nematic-vapour interface. There are significant differences between the structures adopted at the two interfaces, in contrast with the predictions of density functional treatments of such systems.

  4. Episodic Explosions in Interstellar Ices

    CERN Document Server

    Rawlings, J M C; Viti, S; Cecchi-Pestellini, C

    2013-01-01

    We present a model for the formation of large organic molecules in dark clouds. The molecules are produced in the high density gas-phase that exists immediately after ice mantles are explosively sublimated. The explosions are initiated by the catastrophic recombination of trapped atomic hydrogen. We propose that, in molecular clouds, the processes of freeze-out onto ice mantles, accumulation of radicals, explosion and then rapid (three-body) gas-phase chemistry occurs in a cyclic fashion. This can lead to a cumulative molecular enrichment of the interstellar medium. A model of the time-dependent chemistries, based on this hypothesis, shows that significant abundances of large molecular species can be formed, although the complexity of the species is limited by the short expansion timescale in the gas, immediately following mantle explosion. We find that this mechanism may be an important source of smaller organic species, such as methanol and formaldehyde, as well as precursors to bio-molecule formation. Most...

  5. Can STM be used to image molecules on surfaces?

    OpenAIRE

    Ramos, Marta M. D.

    1993-01-01

    The STM's ability to image adsorbates depends on the probability that the electronic states localized on the adsorbed molecule contribute to the tunnelling current. When the STM images are dominated by the substrate, any interpretation in terms of the actual positions of the atoms within the molecule is controversial. A criterion is presented for deciding whether an STM observation is of the adsorbed molecule directly or of the indirect effect of the molecule on the current from the substrate...

  6. Leidenfrost explosions

    CERN Document Server

    Moreau, F; Dorbolo, S

    2012-01-01

    We present a fluid dynamics video showing the behavior of Leidenfrost droplets composed by a mixture of water and surfactant (SDS, Sodium Dodecyl sulfate). When a droplet is released on a plate heated above a given temperature a thin layer of vapor isolates the droplet from the plate. The droplet levitates over the plate. This is called the Leidenfrost effect. In this work we study the influence of the addition of a surfactant on the Leidenfrost phenomenon. As the droplet evaporates the concentration of SDS rises up to two orders of magnitude over the Critical Micelle Concentration (CMC). An unexpected and violent explosive behavior is observed. The video presents several explosions taken with a high speed camera (IDT-N4 at 30000 fps). All the presented experiments were performed on a plate heated at 300{\\deg}C. On the other hand, the initial quantity of SDS was tuned in two ways: (i) by varying the initial concentration of SDS and (ii) by varying the initial size of the droplet. By measuring the volume of th...

  7. Resolving Metazoan phyla divergence times during cambrian explosion by COX I protein molecules%COXI蛋白质分子确定“寒武纪生物大爆发”时期物种分歧时间

    Institute of Scientific and Technical Information of China (English)

    李可群

    2016-01-01

    By using the equation for calculating absolute evolutionary rates of biological molecules presented by the author and classic"molecular clock"Cytochrome oxidase subunit I ( COX I ) protein molecules , the metazoan phyla divergence times during Cambrian explosion were obtained .These results show that Protostomia and Deuterostomia separated at560 million years( myrs ) ago.The phyla divergence times of four major deuterstomia:Cephalochordata , Urochordata, Hemichordata and Echinodermata are 536 myrs ago, 540 myrs ago, 548 myrs ago and 545 myrs ago, respectively.These divergence times agree well with their fossil records , and are obviously better than those obtained by other current molecular clock methods .Our method may provide a new way to understand origins and evo-lution of creatures .%使用经典分子钟分子COX I蛋白质和作者提出的同源生物分子绝对进化速率计算公式,对“寒武纪生物大爆发”期间的一些主要动物门类分歧时间进行了计算。结果表明:原口动物和后口动物分歧时间为5.60亿年前,后口动物中的头索动物、尾索动物、半索动物和棘皮动物的分歧时间分别为5.36亿年前、5.40亿年前、5.48亿年前和5.45亿年前。这些结果与化石记录基本符合,明显好于现有分子钟理论得到的结果。为研究生物起源和演化提供了一种的新的思路和方法。

  8. Chaotic Explosions

    CERN Document Server

    Altmann, Eduardo G; Tél, Tamás

    2015-01-01

    We investigate chaotic dynamical systems for which the intensity of trajectories might grow unlimited in time. We show that (i) the intensity grows exponentially in time and is distributed spatially according to a fractal measure with an information dimension smaller than that of the phase space,(ii) such exploding cases can be described by an operator formalism similar to the one applied to chaotic systems with absorption (decaying intensities), but (iii) the invariant quantities characterizing explosion and absorption are typically not directly related to each other, e.g., the decay rate and fractal dimensions of absorbing maps typically differ from the ones computed in the corresponding inverse (exploding) maps. We illustrate our general results through numerical simulation in the cardioid billiard mimicking a lasing optical cavity, and through analytical calculations in the baker map.

  9. Electronic structure of benzene adsorbed on Ni and Cu surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Weinelt, M.; Nilsson, A.; Wassdahl, N. [Uppsala Univ. (Sweden)] [and others

    1997-04-01

    Benzene has for a long time served as a prototype adsorption system of large molecules. It adsorbs with the molecular plane parallel to the surface. The bonding of benzene to a transition metal is typically viewed to involve the {pi} system. Benzene adsorbs weakly on Cu and strongly on Ni. It is interesting to study how the adsorption strength is reflected in the electronic structure of the adsorbate-substrate complex. The authors have used X-ray Emission (XE) and X-ray Absorption (XA) spectroscopies to selectively study the electronic states localized on the adsorbed benzene molecule. Using XES the occupied states can be studies and with XAS the unoccupied states. The authors have used beamline 8.0 and the Swedish endstation equipped with a grazing incidence x-ray spectrometer and a partial yield absorption detector. The resolution in the XES and XAS were 0.5 eV and 0.05 eV, respectively.

  10. Electronic and electrochemical doping of graphene by surface adsorbates

    OpenAIRE

    Hugo Pinto; Alexander Markevich

    2014-01-01

    Many potential applications of graphene require its precise and controllable doping with charge carriers. Being a two-dimensional material graphene is extremely sensitive to surface adsorbates, so its electronic properties can be effectively modified by deposition of different atoms and molecules. In this paper, we review two mechanisms of graphene doping by surface adsorbates, namely electronic and electrochemical doping. Although, electronic doping has been extensively studied and discussed...

  11. Thermodynamic study of fatty acids adsorption on different adsorbents

    International Nuclear Information System (INIS)

    This work has as objective the study about the adsorption behavior of fatty acids (acetic, propionic, and butyric) on activated carbon and on modified and unmodified montmorillonite clays as a function of temperature and initial concentration of the adsorbate, through adsorption isotherms and their thermodynamic parameters (ΔG, ΔH, and ΔS). The activated carbon presented a higher adsorption capacity due to its relatively large surface area, compared to others adsorbents. The polar characteristic of fatty acids decreased with the increase in the length of non-polar hydrocarbon chain, improving the affinity between the activated carbon (non-polar adsorbent) and the acids. The adsorption capacity of modified montmorillonite (polar adsorbent) was favored due to the presence of the organic cation among its layers, which make the surface more hydrophobic and organophilic when compared to the unmodified montmorillonite surface. The amount of fatty acids adsorbed in the adsorbents surface increased with the concentration, at constant temperature, and decreased with the increase of temperature, at constant concentration. The amount of fatty acids adsorbed in the three adsorbents was related to the surface area and polarity of the adsorbent, concentration and solubility of the adsorbate and temperature of the solution. The negative values of ΔG and ΔH showed that the adsorption on activated carbon and on modified and unmodified montmorillonite clays was a spontaneous and an exothermic process. The decrease in the values of ΔG, with the increase of temperature, demonstrated that the adsorption was benefited by the high temperature and the positive values of ΔS showed that the fatty acids molecules were in a more randomic condition in the adsorbed state than in solution. The experimental results obtained at the temperatures of (298, 303, 313, and 323) K showed that experimental data were well represented by the Langmuir and Freundlich isotherms models

  12. Orbital tomography for highly symmetric adsorbate systems

    Science.gov (United States)

    Stadtmüller, B.; Willenbockel, M.; Reinisch, E. M.; Ules, T.; Bocquet, F. C.; Soubatch, S.; Puschnig, P.; Koller, G.; Ramsey, M. G.; Tautz, F. S.; Kumpf, C.

    2012-10-01

    Orbital tomography is a new and very powerful tool to analyze the angular distribution of a photoemission spectroscopy experiment. It was successfully used for organic adsorbate systems to identify (and consequently deconvolute) the contributions of specific molecular orbitals to the photoemission data. The technique was so far limited to surfaces with low symmetry like fcc(110) oriented surfaces, owing to the small number of rotational domains that occur on such surfaces. In this letter we overcome this limitation and present an orbital tomography study of a 3,4,9,10-perylene-tetra-carboxylic-dianhydride (PTCDA) monolayer film adsorbed on Ag(111). Although this system exhibits twelve differently oriented molecules, the angular resolved photoemission data still allow a meaningful analysis of the different local density of states and reveal different electronic structures for symmetrically inequivalent molecules. We also discuss the precision of the orbital tomography technique in terms of counting statistics and linear regression fitting algorithm. Our results demonstrate that orbital tomography is not limited to low-symmetry surfaces, a finding which makes a broad field of complex adsorbate systems accessible to this powerful technique.

  13. Extrusion cast explosive

    Science.gov (United States)

    Scribner, Kenneth J.

    1985-01-01

    Improved, multiphase, high performance, high energy, extrusion cast explosive compositions, comprising, a crystalline explosive material; an energetic liquid plasticizer; a urethane prepolymer, comprising a blend of polyvinyl formal, and polycaprolactone; a polyfunctional isocyanate; and a catalyst are disclosed. These new explosive compositions exhibit higher explosive content, a smooth detonation front, excellent stability over long periods of storage, and lower sensitivity to mechanical stimulants.

  14. Chemical profiling of explosives

    NARCIS (Netherlands)

    G.M.H. Brust

    2014-01-01

    The primary goal of this thesis is to develop analytical methods for the chemical profiling of explosives. Current methodologies for the forensic analysis of explosives focus on identification of the explosive material. However, chemical profiling of explosives becomes increasingly important, as thi

  15. Interplay of adsorbate-adsorbate and adsorbate-substrate interactions in self-assembled molecular surface nanostructures

    DEFF Research Database (Denmark)

    Schnadt, Joachim; Xu, Wei; Vang, Ronnie Thorbjørn;

    2010-01-01

    The adsorption of 2,6-naphthalenedicarboxylic acid (NDCA) molecules on the Ag(110), Cu(110), and Ag(111) surfaces at room temperature has been studied by means of scanning tunnelling microscopy (STM). Further supporting results were obtained using X-ray photoelectron spectroscopy (XPS) and soft X......-ray absorption spectroscopy (XAS). On the Ag(110) support, which had an average terrace width of only 15 nm, the NDCA molecules form extended one-dimensional (1-D) assemblies, which are oriented perpendicular to the step edges and have lengths of several hundred nanometres. This shows that the assemblies have a......-edge crossing is not observed when the molecules are adsorbed on the isotropic Ag(111) or more reactive Cu(110) surfaces. On Ag(111), similar 1-D assemblies are formed to those on Ag(110), but they are oriented along the step edges. On Cu(110), the carboxylic groups of NDCA are deprotonated and form covalent...

  16. Equilibrium molecular theory of two-dimensional adsorbate drops on surfaces of heterogeneous adsorbents

    Science.gov (United States)

    Tovbin, Yu. K.

    2016-08-01

    A molecular statistical theory for calculating the linear tension of small multicomponent droplets in two-dimensional adsorption systems is developed. The theory describes discrete distributions of molecules in space (on a scale comparable to molecular size) and continuous distributions of molecules (at short distances inside cells) in their translational and vibrational motions. Pair intermolecular interaction potentials (the Mie type potential) in several coordination spheres are considered. For simplicity, it is assumed that distinctions in the sizes of mixture components are slight and comparable to the sizes of adsorbent adsorption centers. Expressions for the pressure tensor components inside small droplets on the heterogeneous surface of an adsorbent are obtained, allowing calculations of the thermodynamic characteristics of a vapor-fluid interface, including linear tension. Problems in refining the molecular theory are discussed: describing the properties of small droplets using a coordination model of their structure, considering the effect an adsorbate has on the state of a near-surface adsorbent region, and the surface heterogeneity factor in the conditions for the formation of droplets.

  17. Zeolites as alcohol adsorbents from aqueous solutions

    Directory of Open Access Journals (Sweden)

    Cekova Blagica

    2006-01-01

    Full Text Available The potential usage of zeolites as adsorbents for the removal of organic molecules from water was investigated in a series of experiments with aqueous solutions of lower alcohols. This could represent a simple solution to the problem of cleaning up industrial wastewater as well as recovering valuable chemicals at relatively low costs. Adsorption isotherms of the Langmuir type were applied, and calculations showed that the amount of propanol adsorbed on silicalite corresponded to approximately 70% of the pore volume. The adsorption process is simple, and recovery of the more concentrated products is easily done by heat treatment and/or at lowered pressures. Adsorption experiments with aqueous acetone showed that silicalite had approximately the same adsorption capacity for acetone as for n-propanol. Heats of adsorption were determined calorimetrically.

  18. Understanding vented gas explosions

    Energy Technology Data Exchange (ETDEWEB)

    Lautkaski, R. [VTT Energy, Espoo (Finland). Energy Systems

    1997-12-31

    The report is an introduction to vented gas explosions for nonspecialists, particularly designers of plants for flammable gases and liquids. The phenomena leading to pressure generation in vented gas explosions in empty and congested rooms are reviewed. The four peak model of vented gas explosions is presented with simple methods to predict the values of the individual peaks. Experimental data on the external explosion of dust and gas explosions is discussed. The empirical equation relating the internal and external peak pressures in vented dust explosions is shown to be valid for gas explosion tests in 30 m{sup 3} and 550 m{sup 3} chambers. However, the difficulty of predicting the internal peak pressure in large chambers remains. Methods of explosion relief panel design and principles of vent and equipment layout to reduce explosion overpressures are reviewed. (orig.) 65 refs.

  19. High performance Mo adsorbent PZC

    Energy Technology Data Exchange (ETDEWEB)

    Anon.

    1998-10-01

    We have developed Mo adsorbents for natural Mo(n, {gamma}){sup 99}Mo-{sup 99m}Tc generator. Among them, we called the highest performance adsorbent PZC that could adsorb about 250 mg-Mo/g. In this report, we will show the structure, adsorption mechanism of Mo, and the other useful properties of PZC when you carry out the examination of Mo adsorption and elution of {sup 99m}Tc. (author)

  20. MOLECULAR IMPRINTED POLYMERS—Novel Polymer Adsorbents

    Institute of Scientific and Technical Information of China (English)

    LIHaitao; XUMancai; 等

    2001-01-01

    Molecular imprinted polymers(MIPs) are novel functional polymer materials and known as specific adsorbents for the template molecules,These novel functional polymers have promised potential applications in racemic resolution,sensor,chromatography,adsorptive separation and other fields.This review exhibits the approach for preparing MIPs,the features of MIPs obtained by different routes and the characteristics of adsorptive separations with MIPs.The molecular recognition mechanism and the idea of the present possibilities and limitations of molecular imprinting polymerization are discussed as well.

  1. Theory of Inelastic Tunneling Current-Driven Motions of Single Adsorbates (Review Article)

    OpenAIRE

    Ueba, H.; Tikhodeev, S. G.; Persson, B.N.J.

    2010-01-01

    The theory of inelastic electron tunneling spectroscopy (IETS) and motions of single adsorbed atoms and molecules on metal surfaces induced by vibrational excitation with a scanning tunneling microscope (STM) is reviewed. The theory of STM-IETS is described using the adsorbate-induced resonance model. Elementary processes of how an adsorbate overcomes the potential barrier along the reaction coordinate (RC) by inelastic tunneling current are described with a focus on direct excitation of the ...

  2. Calculation of Henry constant on the base of critical parameters of adsorbable gas

    International Nuclear Information System (INIS)

    Calculation of Henry constant using correlation between critical parameters Psub(c), Tsub(c) and adsorption energy, determined by the value of internal pressure in molecular field of adsorbent, has been made. The calculated Henry constants for Ar, Kr and Xe, adsorbed by MoS2 and zeolite NaX, are compared with the experimental ones. The state of the molecules adsorbed is evaluated

  3. Synthesis of silica adsorbent and its selective separation for flavone

    Institute of Scientific and Technical Information of China (English)

    Yuqing ZHANG; Yahui ZHANG; Zhen QIN; Zhenrong MA

    2008-01-01

    One kind of built,in silica adsorbent, which has high adsorption selectivity to rutin, was synthesized using molecular imprinting technology by the following steps:synthesis of precursor from the reaction between water soluble rutin (as template molecule) and the functional monomer chloropropyltriethoxysilane, co,hydrolysis of the precursor and tetraethoxysilane (TEOS), sol,gel aging process, and removal of template molecules. The results of adsorption experiment show that this adsorbent has a high adsorption capacity for rutin, and good adsorptionselectivity towards rutin even under the interference of a flavone with a similar structure. TEM photos suggest that nanocaves corresponding to rutin were formed inside the adsorbent while FTIR spectra indicate that new bond was generated during the recognition process.

  4. Substrate-adsorbate coupling in CO-adsorbed copper

    CERN Document Server

    Lewis, S P; Lewis, Steven P.; Rappe, Andrew M.

    1996-01-01

    The vibrational properties of carbon monoxide adsorbed to the copper (100) surface are explored within density functional theory. Atoms of the substrate and adsorbate are treated on an equal footing in order to examine the effect of substrate--adsorbate coupling. This coupling is found to have a significant effect on the vibrational modes, particularly the in-plane frustrated translation, which mixes strongly with substrate phonons and broadens into a resonance. The predicted lifetime due to this harmonic decay mechanism is in excellent quantitative agreement with experiment.

  5. High-resolution scanning tunneling microscopy for molecules

    International Nuclear Information System (INIS)

    Scanning tunneling microscopy (STM) can detect individual molecular configuration with its high spatial resolution ability, but some intrinsical and extrinsic factors result in the complexities of STM imaging of single molecules. By combining STM experimental work and theoretical simulation with the local density approximation based on Bardeen perturbation method, we have explored the atomic-scale configuration of the following molecular systems: C60 molecules adsorbed on Si(1 1 1)-(7x7); alkanethiol self-assembly monolayers on Au(1 1 1); C60 molecule imaged by STM tip adsorbed with another C60 molecule; O2 molecule adsorbed on Ag(1 1 0) and CO molecule adsorbed on Cu(1 1 1) imaged by CO chemically modified STM tip. Some related problems including: molecule-substrate interactions, STM imaging mechanism, chemically modified STM tip, etc., are discussed

  6. Photoinduced Surface Dynamics of CO Adsorbed on a Platinum Electrode

    OpenAIRE

    Noguchi, Hidenori; Okada, Tsubasa; Uosaki, Kohei

    2006-01-01

    The surface dynamics of adsorbed CO molecules formed by dissociative adsorption of HCHO at a polycrystalline Pt electrode/electrolyte solution interface was studied by picosecond time-resolved sum-frequency generation (TR-SFG) spectroscopy. A SFG peak at 2050-2060 cm^[-1] was observed at the Pt electrode in HClO4 solution containing HCHO at 0-300 mV (vs Ag/AgCl), indicating the formation of adsorbed CO at an atop site of the Pt surface as a result of dissociative adsorption of HCHO. The peak ...

  7. STM investigation of surfactant molecules

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Adsorption and self-organization of sodium alkyl sulfonates (STS and SHS) have been studied on HOPG by using the in situ scanning tunneling microscopy (STM). Both SHS and STS molecules adsorb on the HOPG surface and form long-range well-ordered monolayers. The neighboring molecules in different rows form a "head to head" configuration. In the high-resolution images of STS and SHS molecules, one end of the molecules shows bright spots which are attributed to the SO3- groups.

  8. Molecular adsorbates under high pressure: a study using surface-enhanced Raman scattering spectroscopy

    International Nuclear Information System (INIS)

    Molecules adsorbed on metal surfaces were studied in a diamond anvil cell with Ar pressure-transmission medium up to several GPa pressure using Raman spectroscopy. The problem with studying molecules on surfaces is the small number density. This problem was overcome using photonic substrates to amplify the Raman intensity by factors of 106 in the case of self-assembled monolayers on Ag-coated nanoarrays, where the probed region contained ∼109 molecules, and >109 in the case of the dye Rhodamine 6G on Ag nanoaggregates, where <106 molecules were probed. Pressure effects on the adsorbate vibrations and on the underlying nanostructures are discussed.

  9. 76 FR 64974 - Commerce in Explosives; List of Explosive Materials (2011R-18T)

    Science.gov (United States)

    2011-10-19

    ... inorganic salts. * ANFO . Aromatic nitro-compound explosive mixtures. Azide explosives. B Baranol. Baratol...). Explosive nitro compounds of aromatic hydrocarbons. Explosive organic nitrate mixtures. Explosive powders. F... explosive. Nitrated polyhydric alcohol explosives. Nitric acid and a nitro aromatic compound...

  10. 75 FR 1085 - Commerce in Explosives; List of Explosive Materials (2009R-18T)

    Science.gov (United States)

    2010-01-08

    .... *ANFO . Aromatic nitro-compound explosive mixtures. Azide explosives. B Baranol. Baratol. BEAF . Black...). Explosive nitro compounds of aromatic hydrocarbons. Explosive organic nitrate mixtures. Explosive powders. F... explosive. Nitrated polyhydric alcohol explosives. Nitric acid and a nitro aromatic compound...

  11. Distribution of adsorbed molecules in electronic nose sensors

    DEFF Research Database (Denmark)

    Swann, M.J.; Glidle, A.; Gadegaard, Nikolaj;

    2000-01-01

    Neutron reflectivity measurements of thin films of electropolymerised poly(pyrrole) show that swelling of these insoluble polymers does occur following vapour adsorption. The variation in swelling found for different vapours is correlated with corresponding changes in polymer conductivity and mas...

  12. Explosive Technology Group

    Data.gov (United States)

    Federal Laboratory Consortium — The Explosive Technology Group (ETG) provides diverse technical expertise and an agile, integrated approach to solve complex challenges for all classes of energetic...

  13. Why not only electric discharge but even a minimum charge on the surface of highly sensitive explosives can catalyze their gradual exothermic decomposition and how a cloud of unipolar charged explosive particles turns into ball lightning

    CERN Document Server

    Meshcheryakov, Oleg

    2014-01-01

    Even a single excess electron or ion migrating on the surface of sensitive explosives can catalyze their gradual exothermic decomposition. Mechanisms underlying such a charge-induced gradual thermal decomposition of highly sensitive explosives can be different. If sensitive explosive is a polar liquid, intense charge-dipole attraction between excess surface charges and surrounding explosive molecules can result in repetitive attempts of solvation of these charges by polar explosive molecules. Every attempt of such uncompleted nonequilibrium solvation causes local exothermic decomposition of thermolabile polar molecules accompanied by further thermal jumping unsolvated excess charges to new surface sites. Thus, ionized mobile hot spots emerge on charged explosive surface. Stochastic migration of ionized hot spots on explosive surface causes gradual exothermic decomposition of the whole mass of the polar explosive. The similar gradual charge-catalyzed exothermic decomposition of both polar and nonpolar highly s...

  14. Steam explosion studies review

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Moon Kyu; Kim, Hee Dong

    1999-03-01

    When a cold liquid is brought into contact with a molten material with a temperature significantly higher than the liquid boiling point, an explosive interaction due to sudden fragmentation of the melt and rapid evaporation of the liquid may take place. This phenomenon is referred to as a steam explosion or vapor explosion. Depending upon the amount of the melt and the liquid involved, the mechanical energy released during a vapor explosion can be large enough to cause serious destruction. In hypothetical severe accidents which involve fuel melt down, subsequent interactions between the molten fuel and coolant may cause steam explosion. This process has been studied by many investigators in an effort to assess the likelihood of containment failure which leads to large scale release of radioactive materials to the environment. In an effort to understand the phenomenology of steam explosion, extensive studies has been performed so far. The report presents both experimental and analytical studies on steam explosion. As for the experimental studies, both small scale tests which involve usually less than 20 g of high temperature melt and medium/large scale tests which more than 1 kg of melt is used are reviewed. For the modelling part of steam explosions, mechanistic modelling as well as thermodynamic modelling is reviewed. (author)

  15. Steam explosion studies review

    International Nuclear Information System (INIS)

    When a cold liquid is brought into contact with a molten material with a temperature significantly higher than the liquid boiling point, an explosive interaction due to sudden fragmentation of the melt and rapid evaporation of the liquid may take place. This phenomenon is referred to as a steam explosion or vapor explosion. Depending upon the amount of the melt and the liquid involved, the mechanical energy released during a vapor explosion can be large enough to cause serious destruction. In hypothetical severe accidents which involve fuel melt down, subsequent interactions between the molten fuel and coolant may cause steam explosion. This process has been studied by many investigators in an effort to assess the likelihood of containment failure which leads to large scale release of radioactive materials to the environment. In an effort to understand the phenomenology of steam explosion, extensive studies has been performed so far. The report presents both experimental and analytical studies on steam explosion. As for the experimental studies, both small scale tests which involve usually less than 20 g of high temperature melt and medium/large scale tests which more than 1 kg of melt is used are reviewed. For the modelling part of steam explosions, mechanistic modelling as well as thermodynamic modelling is reviewed. (author)

  16. Explosions and static electricity

    DEFF Research Database (Denmark)

    Jonassen, Niels M

    1995-01-01

    The paper deals with the problem of electrostatic discharges as causes of ignition of vapor/gas and dust/gas mixtures. A series of examples of static-caused explosions will be discussed. The concepts of explosion limits, the incendiveness of various discharge types and safe voltages are explained...

  17. Au(111)表面吸附单个八乙基钴卟啉分子的电子态和输运性质调控%Controlling the electronic states and transport properties of single cobalt(II)octaethylporphyrin molecule adsorbed on Au(111) surface

    Institute of Scientific and Technical Information of China (English)

    李竟成; 赵爱迪; 王兵

    2015-01-01

    We demonstrate that the molecular ligands play important roles in controlling the electronic states and electron transport properties of single cobalt (II) octaethylporphyrin (CoOEP) molecule adsorbed on Au(111) surface by using low-temperature scanning tunneling microscopy and spectroscopy. Single CoOEP molecule adsorbed on Au(111) surface has eight methyl groups pointing out of the surface plane. A peak located at−50 mV in dI/dV spectrum measured on the Co atom of CoOEP is identified as a d-orbital mediated resonance. We find that the methyl groups in CoOEP can be removed in a stepwise manner, and finally lead to a fully-demethylized CoOEP. The d-orbital mediated resonance gradually evolves into a sharp Kondo resonance located right at Fermi level in the demethylization process. Both experimental and theoretical results indicate that the chemical environment and magnetic moment of the central Co atom change slightly in the fully-demethylized CoOEP: the Co atom is slightly lifted by 0.15 Å and the magnetic moment increases from 0.5 µB to 0.6 µB. The emergence of Kondo effect is qualitatively explained with a simple model by consideringthe change in the tunneling parameters of the ligands upon demethylization. We also show that the transport properties of the CoOEP can be dramatically controlled by weak intramolecular van der Waals interaction. In CoOEP closely-packed dimers and trimers where CoOEP molecules are introduced close enough to each other, the ethyl groups in the neighboring area are found to be strongly lifted by 0.4 Å. More surprisingly, a pronounced resonance shows up at 0—0.8 V in the dI/dV spectra of the lifted ethyl groups. High resolution spectra show that the new resonance consists of multiple peaks with equal spacing of 137 ± 8 mV. The spacing energy coincides with the vibrational energy of stretching mode of C—C bond between ethyl group and the brim carbon atom of the porphyrin ring. Therefore the newly-emerged resonance is

  18. CONDUCTIVITY METHOD APPLIED TO THE STUDY OF INTERACTION BETWEEN ADSORBENT AND ADSORBATE I.ADSORPTION OF LOW CONCENYRATION OF FREE ACID BY REGENERABLE CHITIN

    Institute of Scientific and Technical Information of China (English)

    ChenBingren; HeGuangping; 等

    1997-01-01

    The adsorption of low concentration of free acid by regenerable chitin is followed by electric conductance determination.The effect of acid concentratioin,content of functioinal amino groups,and ionic strength on adsorption was discussed.Experimental results indicate that the active centre of regenerable chitin is the free amino groups on ist surface ,and that the rate of adsorption of free acid was found to be affected by two factors:the interaction between the adsorbent and the adsorbate in solution and that between the adsorbate molecules or ions in solution.

  19. Controlled contact to a C-60 molecule

    DEFF Research Database (Denmark)

    Neel, N.; Kröger, J.; Limot, L.;

    2007-01-01

    The tip of a low-temperature scanning tunneling microscope is approached towards a C-60 molecule adsorbed at a pentagon-hexagon bond on Cu(100) to form a tip-molecule contact. The conductance rapidly increases to approximate to 0.25 conductance quanta in the transition region from tunneling...

  20. Ordered molecular layer structure of lubricating oil adsorbed films

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Low-angle X-ray diffraction has been applied to analyze the structure of stearic acid LB films and self-grown surface adsorbed films of aluminium product metalworking lubricants. The results show that LB films exhibit a good layer-like ordered structure in the normal direction of film-carrying surface, while in the tangential direction, they do not show a cyclically ordered molecular arrangement; as for the self-grown surface adsorbed films of aluminium sheet and strip metalworking lubricants, their molecules are orderly arranged to certain degree in both the tangential and the normal directions of film-carrying surface, and they have a short-range ordered structure. Moreover, the better the orientation of normal molecules is, the higher the oil film strength is, and the smaller the friction factor is.

  1. A Window on Surface Explosions: Tartaric Acid on Cu(110)

    Energy Technology Data Exchange (ETDEWEB)

    Mhatre, B S; Pushkarev, V; Holsclaw, B; Lawton, T J; Sykes, E C. H.; Gellman, A J

    2013-04-18

    Autocatalytic reaction mechanisms are observed in a range of important chemical processes including catalysis, radical-mediated explosions, and biosynthesis. Because of their complexity, the microscopic details of autocatalytic reaction mechanisms have been difficult to study on surfaces and heterogeneous catalysts. Autocatalytic decomposition reactions of S,S- and R,R-tartaric acid (TA) adsorbed on Cu(110) offer molecular-level insight into aspects of these processes, which until now, were largely a matter of speculation. The decomposition of TA/Cu(110) is initiated by a slow, irreversible process that forms vacancies in the adsorbed TA layer, followed by a vacancy-mediated, explosive decomposition process that yields CO{sub 2} and small hydrocarbon products. Initiation of the explosive decomposition of TA/Cu(110) has been studied by measurement of the reaction kinetics, time-resolved low energy electron diffraction (LEED), and time-resolved scanning tunneling microscopy (STM). Initiation results in a decrease in the local coverage of TA and a concomitant increase in the areal vacancy concentration. Observations of explosive TA decomposition on the Cu(651)S surface suggest that initiation does not occur at structural defects in the surface, as has been suggested in the past. Once the vacancy concentration reaches a critical value, the explosive, autocatalytic decomposition step dominates the TA decomposition rate. The onset of the explosive decomposition of TA on Cu(110) is accompanied by the extraction of Cu atoms from the surface to form a (±6,7; {-+}2,1) overlayer that is readily observable using LEED and STM. The explosive decomposition step is second-order in vacancy concentration and accelerates with increasing extent of reaction.

  2. 扩张床吸附剂:制备及功能化%Adsorbents for Expanded Bed Adsorption: Preparation and Functionalization

    Institute of Scientific and Technical Information of China (English)

    赵珺; 姚善泾; 林东强

    2009-01-01

    Expanded bed adsorption (EBA), a promising and practical separation technique, has been widely stud-ied in the past two decades. The development of adsorbents for EBA process is a challenging course, with the spe-cial design and preparation according to the target molecules and specific expanded bed systems. Many types of supporting matrices for expanded bed adsorbents have been developed, and their preparation methods are being consummated gradually. These matrices are activated and then coupled with ligands to form functionalized adsorb-ents, including ion-exchange adsorbents, affinity adsorbents, mixed mode adsorbents, hydrophobic charge induction chromatography adsorbents and others. In this review, the preparation of the matrices for EBA process is summa-rized, and the coupling of ligands to the matrices to prepare functionalized adsorbents is discussed as well.

  3. Micro-solid-phase extraction coupled to desorption electrospray ionization-high-resolution mass spectrometry for the analysis of explosives in soil

    DEFF Research Database (Denmark)

    Bianchi, Federica; Gregori, Adolfo; Braun, Gabriele;

    2015-01-01

    Home-made micro-solid-phase extraction (SPE) cartridges using different adsorbent materials were tested for the desorption electrospray ionization-high-resolution mass spectrometry (DESI-HRMS) determination of explosives like 2,4,6-trinitrotoluene, cyclotrimethylene-trinitramine, cyclotetramethyl......Home-made micro-solid-phase extraction (SPE) cartridges using different adsorbent materials were tested for the desorption electrospray ionization-high-resolution mass spectrometry (DESI-HRMS) determination of explosives like 2,4,6-trinitrotoluene, cyclotrimethylene...

  4. Liquid explosives detection

    Science.gov (United States)

    Burnett, Lowell J.

    1994-03-01

    A Liquid Explosives Screening System capable of scanning unopened bottles for liquid explosives has been developed. The system can be operated to detect specific explosives directly, or to verify the labeled or bar-coded contents of the container. In this system nuclear magnetic resonance (NMR) is used to interrogate the liquid. NMR produces an extremely rich data set and many parameters of the NMR response can be determined simultaneously. As a result, multiple NMR signatures may be defined for any given set of liquids, and the signature complexity then selected according to the level of threat.

  5. Graphene symmetry-breaking with molecular adsorbates: modeling and experiment

    Science.gov (United States)

    Groce, M. A.; Hawkins, M. K.; Wang, Y. L.; Cullen, W. G.; Einstein, T. L.

    2012-02-01

    Graphene's structure and electronic properties provide a framework for understanding molecule-substrate interactions and developing techniques for band gap engineering. Controlled deposition of molecular adsorbates can create superlattices which break the degeneracy of graphene's two-atom unit cell, opening a band gap. We simulate scanning tunneling microscopy and spectroscopy measurements for a variety of organic molecule/graphene systems, including pyridine, trimesic acid, and isonicotinic acid, based on density functional theory calculations using VASP. We also compare our simulations to ultra-high vacuum STM and STS results.

  6. Temperature programmed desorption of weakly bound adsorbates on Au(111)

    Science.gov (United States)

    Engelhart, Daniel P.; Wagner, Roman J. V.; Meling, Artur; Wodtke, Alec M.; Schäfer, Tim

    2016-08-01

    We have performed temperature programmed desorption (TPD) experiments to analyze the desorption kinetics of Ar, Kr, Xe, C2H2, SF6, N2, NO and CO on Au(111). We report desorption activation energies (Edes), which are an excellent proxy for the binding energies. The derived binding energies scale with the polarizability of the molecules, consistent with the conclusion that the surface-adsorbate bonds arise due to dispersion forces. The reported results serve as a benchmark for theories of dispersion force interactions of molecules at metal surfaces.

  7. Explosive Components Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The 98,000 square foot Explosive Components Facility (ECF) is a state-of-the-art facility that provides a full-range of chemical, material, and performance analysis...

  8. Intermittent Explosive Disorder

    Directory of Open Access Journals (Sweden)

    Lut Tamam

    2011-09-01

    Full Text Available Intermittent explosive disorder is an impulse control disorder characterized by the occurrence of discrete episodes of failure to resist aggressive impulses that result in violent assault or destruction of property. Though the prevalence intermittent explosive disorder has been reported to be relatively rare in frontier studies on the field, it is now common opinion that intermittent explosive disorder is far more common than previously thought especially in clinical psychiatry settings. Etiological studies displayed the role of both psychosocial factors like childhood traumas and biological factors like dysfunctional neurotransmitter systems and genetics. In differential diagnosis of the disorder, disorders involving agression as a symptom such as alcohol and drug intoxication, antisocial and borderline personality disorders, personality changes due to general medical conditions and behavioral disorder should be considered. A combination of pharmacological and psychotherapeutic approaches are suggested in the treatment of the disorder. This article briefly reviews the historical background, diagnostic criteria, epidemiology, etiology and treatment of intermittent explosive disorder.

  9. Shock waves & explosions

    CERN Document Server

    Sachdev, PL

    2004-01-01

    Understanding the causes and effects of explosions is important to experts in a broad range of disciplines, including the military, industrial and environmental research, aeronautic engineering, and applied mathematics. Offering an introductory review of historic research, Shock Waves and Explosions brings analytic and computational methods to a wide audience in a clear and thorough way. Beginning with an overview of the research on combustion and gas dynamics in the 1970s and 1980s, the author brings you up to date by covering modeling techniques and asymptotic and perturbative methods and ending with a chapter on computational methods.Most of the book deals with the mathematical analysis of explosions, but computational results are also included wherever they are available. Historical perspectives are provided on the advent of nonlinear science, as well as on the mathematical study of the blast wave phenomenon, both when visualized as a point explosion and when simulated as the expansion of a high-pressure ...

  10. Modeling nuclear explosion

    Science.gov (United States)

    Redd, Jeremy; Panin, Alexander

    2012-10-01

    As a result of the Nuclear Test Ban Treaty, no nuclear explosion tests have been performed by the US since 1992. This appreciably limits valuable experimental data needed for improvement of existing weapons and development of new ones, as well as for use of nuclear devices in non-military applications (such as making underground oil reservoirs or compressed air energy storages). This in turn increases the value of numerical modeling of nuclear explosions and of their effects on the environment. We develop numerical codes simulating fission chain reactions in a supercritical U and Pu core and the dynamics of the subsequent expansion of generated hot plasma in order to better understand the impact of such explosions on their surroundings. The results of our simulations (of both above ground and underground explosions) of various energy yields are presented.

  11. Parametric Explosion Spectral Model

    Energy Technology Data Exchange (ETDEWEB)

    Ford, S R; Walter, W R

    2012-01-19

    Small underground nuclear explosions need to be confidently detected, identified, and characterized in regions of the world where they have never before occurred. We develop a parametric model of the nuclear explosion seismic source spectrum derived from regional phases that is compatible with earthquake-based geometrical spreading and attenuation. Earthquake spectra are fit with a generalized version of the Brune spectrum, which is a three-parameter model that describes the long-period level, corner-frequency, and spectral slope at high-frequencies. Explosion spectra can be fit with similar spectral models whose parameters are then correlated with near-source geology and containment conditions. We observe a correlation of high gas-porosity (low-strength) with increased spectral slope. The relationship between the parametric equations and the geologic and containment conditions will assist in our physical understanding of the nuclear explosion source.

  12. A theoretical study of the interaction of hydrogen and oxygen with palladium or gold adsorbed on pyridine-like nitrogen-doped graphene.

    Science.gov (United States)

    Rangel, Eduardo; Magana, Luis Fernando; Sansores, Luis Enrique

    2014-12-15

    The interaction of H2 and O2 molecules in the presence of nitrogen-doped graphene decorated with either a palladium or gold atom was investigated by using density functional theory. It was found that two hydrogen molecules were adsorbed on the palladium atom. The interaction of these adsorbed hydrogen molecules with two oxygen molecules generates two hydrogen peroxide molecules first through a Eley-Rideal mechanism and then through a Langmuir-Hinshelwood mechanism. The barrier energies for this reaction were small; therefore, we expect that this process may occur spontaneously at room temperature. In the case of gold, a single hydrogen molecule is adsorbed and dissociated on the metal atom. The interaction of the dissociated hydrogen molecule on the surface with one oxygen molecule generates a water molecule. The competitive adsorption between oxygen and hydrogen molecules slightly favors oxygen adsorption.

  13. Aging of civil explosives (Poster)

    NARCIS (Netherlands)

    Krabbendam-La Haye, E.L.M.; Klerk, W.P.C. de; Hoen, C. 't; Krämer, R.E.

    2014-01-01

    For the Dutch MoD and police, TNO composed sets with different kinds of civil explosives to train their detection dogs. The manufacturer of these explosives guarantees several years of stability of these explosives. These sets of explosives are used under different conditions, like temperature and h

  14. Modelling of gas explosions

    OpenAIRE

    Vågsæther, Knut

    2010-01-01

    The content of this thesis is a study of gas explosions in complex geometries and presentation and validation of a method for simulating flame acceleration and deflagration to detonation transition. The thesis includes a description of the mechanisms of flame acceleration and DDT that need to be modeled when simulating all stages of gas explosions. These mechanisms are flame acceleration due to instabilities that occur in fluid flow and reactive systems, shock propagation, deflagration to det...

  15. Explosive Welding with Nitroguanidine.

    Science.gov (United States)

    Sadwin, L D

    1964-03-13

    By using the explosive nitroguanidine, continuous welds can be made between similar and dissimilar metals. Since low detonation pressures are attainable, pressure transfer media are not required between the explosive and the metal surface. The need for either a space or an angle between the metals is eliminated, and very low atmospheric pressures are not required. Successful welds have been made between tantalum and 4140 steel, 3003H14 aluminum and 4140 steel, and 304 stainless steel and 3003H14 aluminum.

  16. Chemical Explosion Database

    Science.gov (United States)

    Johansson, Peder; Brachet, Nicolas

    2010-05-01

    A database containing information on chemical explosions, recorded and located by the International Data Center (IDC) of the CTBTO, should be established in the IDC prior to entry into force of the CTBT. Nearly all of the large chemical explosions occur in connection with mining activity. As a first step towards the establishment of this database, a survey of presumed mining areas where sufficiently large explosions are conducted has been done. This is dominated by the large coal mining areas like the Powder River (U.S.), Kuznetsk (Russia), Bowen (Australia) and Ekibastuz (Kazakhstan) basins. There are also several other smaller mining areas, in e.g. Scandinavia, Poland, Kazakhstan and Australia, with large enough explosions for detection. Events in the Reviewed Event Bulletin (REB) of the IDC that are located in or close to these mining areas, and which therefore are candidates for inclusion in the database, have been investigated. Comparison with a database of infrasound events has been done as many mining blasts generate strong infrasound signals and therefore also are included in the infrasound database. Currently there are 66 such REB events in 18 mining areas in the infrasound database. On a yearly basis several hundreds of events in mining areas have been recorded and included in the REB. Establishment of the database of chemical explosions requires confirmation and ground truth information from the States Parties regarding these events. For an explosion reported in the REB, the appropriate authority in whose country the explosion occurred is encouraged, on a voluntary basis, to seek out information on the explosion and communicate this information to the IDC.

  17. Thermodynamic formalism of water uptakes on solid porous adsorbents for adsorption cooling applications

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Baichuan; Chakraborty, Anutosh, E-mail: AChakraborty@ntu.edu.sg [School of Mechanical and Aerospace Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

    2014-05-19

    This Letter presents a thermodynamic formulation to calculate the amount of water vapor uptakes on various adsorbents such as zeolites, metal organic frameworks, and silica gel for the development of an advanced adsorption chiller. This formalism is developed from the rigor of the partition distribution function of each water vapor adsorptive site on adsorbents and the condensation approximation of adsorptive water molecules and is validated with experimental data. An interesting and useful finding has been established that the proposed model is thermodynamically connected with the pore structures of adsorbent materials, and the water vapor uptake highly depends on the isosteric heat of adsorption at zero surface coverage and the adsorptive sites of the adsorbent materials. Employing the proposed model, the thermodynamic trends of water vapor uptakes on various adsorbents can be estimated.

  18. Thermodynamic formalism of water uptakes on solid porous adsorbents for adsorption cooling applications

    Science.gov (United States)

    Sun, Baichuan; Chakraborty, Anutosh

    2014-05-01

    This Letter presents a thermodynamic formulation to calculate the amount of water vapor uptakes on various adsorbents such as zeolites, metal organic frameworks, and silica gel for the development of an advanced adsorption chiller. This formalism is developed from the rigor of the partition distribution function of each water vapor adsorptive site on adsorbents and the condensation approximation of adsorptive water molecules and is validated with experimental data. An interesting and useful finding has been established that the proposed model is thermodynamically connected with the pore structures of adsorbent materials, and the water vapor uptake highly depends on the isosteric heat of adsorption at zero surface coverage and the adsorptive sites of the adsorbent materials. Employing the proposed model, the thermodynamic trends of water vapor uptakes on various adsorbents can be estimated.

  19. Black Sprayable Molecular Adsorber Coating Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This novel molecular adsorber coating would alleviate the size, weight, and complexity issues of traditional molecular adsorber puck.  A flexible tape version...

  20. Underground explosion barriers - a review

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, B.; O`Beirne, T. [ACIRL Ltd., Booval, Qld. (Australia)

    1997-12-31

    The paper focuses on explosibility conditions in underground coal mines, the behaviour of explosions from initiating gas ignition to violent dust explosions and the effectiveness and limits of operation of current designs of passive explosion barriers in suppressing the flame front. The paper also discusses performance evaluations made in full scale explosion galleries and the use of alternatives to passive barriers, including the installation of active barriers under some circumstances.

  1. Narrow-pore zeolites and zeolite-like adsorbents for CO2 separation

    OpenAIRE

    Cheung, Ocean

    2014-01-01

    A range of porous solid adsorbents were synthesised and their ability to separate and capture carbon dioxide (CO2) from gas mixtures was examined. CO2 separation from flue gas – a type of exhaust gas from fossil fuel combustion that consists of CO2 mixed with mainly nitrogen and biogas (consists of CO2 mixed with mainly methane) were explicitly considered. The selected adsorbents were chosen partly due to their narrow pore sizes. Narrow pores can differentiate gas molecules of different sizes...

  2. Atomic-Scale Control of Electron Transport through Single Molecules

    DEFF Research Database (Denmark)

    Wang, Y. F.; Kroger, J.; Berndt, R.;

    2010-01-01

    Tin-phthalocyanine molecules adsorbed on Ag(111) were contacted with the tip of a cryogenic scanning tunneling microscope. Orders-of-magnitude variations of the single-molecule junction conductance were achieved by controllably dehydrogenating the molecule and by modifying the atomic structure of...

  3. Protein purification using magnetic adsorbent particles

    DEFF Research Database (Denmark)

    Franzreb, M; Siemann-Herzberg, M.; Hobley, Timothy John;

    2006-01-01

    The application of functionalised magnetic adsorbent particles in combination with magnetic separation techniques has received considerable attention in recent years. The magnetically responsive nature of such adsorbent particles permits their selective manipulation and separation in the presence...... of development of protein separation using magnetic adsorbent particles and identify the obstacles that must be overcome if protein purification with magnetic adsorbent particles is to find its way into industrial practice....... of other suspended solids. Thus, it becomes possible to magnetically separate selected target species directly out of crude biological process liquors (e.g. fermentation broths, cell disruptates, plasma, milk, whey and plant extracts) simply by binding them on magnetic adsorbents before application...

  4. Distribution of metal and adsorbed guest species in zeolites

    International Nuclear Information System (INIS)

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes 129Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of 129Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, 129Xe NMR is insensitive to fine structural details at room temperature

  5. Distribution of metal and adsorbed guest species in zeolites

    Energy Technology Data Exchange (ETDEWEB)

    Chmelka, B.F.

    1989-12-01

    Because of their high internal surface areas and molecular-size cavity dimensions, zeolites are used widely as catalysts, shape- selective supports, or adsorbents in a variety of important chemical processes. For metal-catalyzed reactions, active metal species must be dispersed to sites within the zeolite pores that are accessible to diffusing reactant molecules. The distribution of the metal, together with transport and adsorption of reactant molecules in zeolite powders, are crucial to ultimate catalyst performance. The nature of the metal or adsorbed guest distribution is known, however, to be dramatically dependent upon preparatory conditions. Our objective is to understand, at the molecular level, how preparatory treatments influence the distribution of guest species in zeolites, in order that macroscopic adsorption and reaction properties of these materials may be better understood. The sensitivity of xenon to its adsorption environment makes {sup 129}Xe NMR spectroscopy an important diagnostic probe of metal clustering and adsorbate distribution processes in zeolites. The utility of {sup 129}Xe NMR depends on the mobility of the xenon atoms within the zeolite-guest system, together with the length scale of the sample heterogeneity being studied. In large pore zeolites containing dispersed guest species, such as Pt--NaY, {sup 129}Xe NMR is insensitive to fine structural details at room temperature.

  6. Molecule nanoweaver

    Science.gov (United States)

    Gerald, II; Rex E.; Klingler, Robert J.; Rathke, Jerome W.; Diaz, Rocio; Vukovic, Lela

    2009-03-10

    A method, apparatus, and system for constructing uniform macroscopic films with tailored geometric assemblies of molecules on the nanometer scale. The method, apparatus, and system include providing starting molecules of selected character, applying one or more force fields to the molecules to cause them to order and condense with NMR spectra and images being used to monitor progress in creating the desired geometrical assembly and functionality of molecules that comprise the films.

  7. Explosive Welding with Nitroguanidine.

    Science.gov (United States)

    Sadwin, L D

    1964-03-13

    By using the explosive nitroguanidine, continuous welds can be made between similar and dissimilar metals. Since low detonation pressures are attainable, pressure transfer media are not required between the explosive and the metal surface. The need for either a space or an angle between the metals is eliminated, and very low atmospheric pressures are not required. Successful welds have been made between tantalum and 4140 steel, 3003H14 aluminum and 4140 steel, and 304 stainless steel and 3003H14 aluminum. PMID:17833901

  8. Molecular structure and Equilibrium forces of bovine submaxillary mucin adsorbed at a solid-liquid interface

    DEFF Research Database (Denmark)

    Zappone, Bruno; Patil, Navinkumar J.; Madsen, Jan Busk;

    2015-01-01

    By combining dynamic light scattering, circular dichroism spectroscopy, atomic force microscopy, and surface force apparatus, the conformation of bovine submaxillary mucin in dilute solution and nanomechanical properties of mucin layers adsorbed on mica have been investigated. The samples were......, yet of the same order of magnitude as the diameter, indicating that the molecule can be modeled as a relatively rigid polymeric chain due to the large persistence length of the central glycosylated domain. Mucin molecules adsorbed abundantly onto mica from saline buffer, generating polymer-like, long...

  9. Dynamics of copper-phthalocyanine molecules on Au/Ge(001)

    NARCIS (Netherlands)

    Sotthewes, K.; Heimbuch, R.U.; Zandvliet, H.J.W.

    2015-01-01

    Spatially resolved current-time scanning tunneling spectroscopy combined with current-distance spectroscopy has been used to characterize the dynamic behavior of copper-phthalocyanine (CuPc) molecules adsorbed on a Au-modified Ge(001) surface. The analyzed CuPc molecules are adsorbed in a “molecular

  10. 77 FR 58410 - Commerce in Explosives; List of Explosive Materials (2012R-10T)

    Science.gov (United States)

    2012-09-20

    ... salt lattice with isomorphously substituted inorganic salts. * ANFO . Aromatic nitro-compound explosive.... Explosive mixtures containing tetranitromethane (nitroform). Explosive nitro compounds of aromatic... polyhydric alcohol explosives. Nitric acid and a nitro aromatic compound explosive. Nitric acid...

  11. 75 FR 70291 - Commerce in Explosives; List of Explosive Materials (2010R-27T)

    Science.gov (United States)

    2010-11-17

    ... salt lattice with isomorphously substituted inorganic salts. * ANFO . Aromatic nitro-compound explosive.... Explosive mixtures containing tetranitromethane (nitroform). Explosive nitro compounds of aromatic... polyhydric alcohol explosives. Nitric acid and a nitro aromatic compound explosive. Nitric acid...

  12. Polar molecule dominated electrorheological effect

    Institute of Scientific and Technical Information of China (English)

    Lu Kun-Quan; Shen Rong; Wang Xue-Zhao; Sun Gang; Wen Wei-Jia; Liu Ji-Xing

    2006-01-01

    The yield stress of our newly developed electrorheological (ER) fluids consisting of dielectric nano-particles suspended in silicone oil reaches hundreds of kPa, which is orders of magnitude higher than that of conventional ones. We found that the polar molecules adsorbed on the particles play a decisive role in such new ER fluids. To explain this polar molecule dominated ER (PM-ER) effect a model is proposed based on the interaction of polar molecule-charge between the particles, where the local electric field is significantly enhanced and results in the polar molecules aligning in the direction of the electric field. The model can well explain the giant ER effect and a near-linear dependence of the yield stress on the electric field. The main effective factors for achieving high-performance PM-ER fluids are discussed. The PM-ER fluids with the yield stress higher than one MPa can be expected.

  13. Nanostructured surface enhanced Raman scattering substrates for explosives detection

    DEFF Research Database (Denmark)

    Schmidt, Michael Stenbaek; Olsen, Jesper Kenneth; Boisen, Anja;

    2010-01-01

    molecules adsorbed onto the substrate. The substrates were fabricated in a cleanroom process which only requires two steps to produce well controlled nano-sized high aspect ratio metal pillars. These substrates had superior chemical sensing performance in addition to a more cost effective fabrication...

  14. Portable raman explosives detection

    Energy Technology Data Exchange (ETDEWEB)

    Moore, David Steven [Los Alamos National Laboratory; Scharff, Robert J [Los Alamos National Laboratory

    2008-01-01

    Recent advances in portable Raman instruments have dramatically increased their application to emergency response and forensics, as well as homeland defense. This paper reviews the relevant attributes and disadvantages of portable Raman spectroscopy, both essentially and instrumentally, to the task of explosives detection in the field.

  15. A novel fiber-based adsorbent technology

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, T.A. [Chemica Technologies, Inc., Bend, OR (United States)

    1997-10-01

    In this Phase I Small Business Innovation Research program, Chemica Technologies, Inc. is developing an economical, robust, fiber-based adsorbent technology for removal of heavy metals from contaminated water. The key innovation is the development of regenerable adsorbent fibers and adsorbent fiber cloths that have high capacity and selectivity for heavy metals and are chemically robust. The process has the potential for widespread use at DOE facilities, mining operations, and the chemical process industry.

  16. Recovery of Th(IV) from aqueous solution by reassembled collagen-tannin fiber adsorbent

    International Nuclear Information System (INIS)

    A novel adsorbent, collagen immobilized tannin adsorbent (CITA), was prepared and its adsorption behaviors to Th(IV) were investigated. CITA was n fibrous state due to the reassembly of collagen molecules by the inducement of tannin. This adsorbent loaded a greater amount of tannin and exhibited higher adsorption capacity to Th(IV) than the tannin immobilized adsorbent prepared from collagen fiber. The adsorption of CITA to Th(IV) is mainly attributed to surface complexation, which is a pH- rather than an ionic strength-dependent process. The adsorption kinetics and isotherms were described by pseudo-second-order rate model and Freundlich equation, respectively. Column adsorption studies indicated that CITA is available for effectively recovering Th(IV) from aqueous solution. (author)

  17. Magnetic susceptibility of oxygen adsorbed on the surface of spherical and fibrous activated carbon.

    Directory of Open Access Journals (Sweden)

    Kiyoshi Kawamura

    2009-02-01

    Full Text Available The magnetic susceptibilities of oxygen adsorbed on the surface of bead-shaped activated carbon and activated carbon fibers were evaluated as a function of temperature between 4.2 K and 300 K, and found to exhibit a sharp peak at around 50 K. This implies that the adsorbed oxygen molecules form an antiferromagnetic state. The relation between the susceptibility and the adsorbed mass suggest that the thickness of the adsorbed oxygen is thin enough to consider a two-dimensional structure for bead–shaped activated carbon and carbon fibers across the fiber axis but thick enough to regard it as three-dimensional along the fiber axis. The result is discussed with reference to the study on one-dimensional oxygen array.

  18. Structure of adsorbed monolayers. The surface chemical bond

    International Nuclear Information System (INIS)

    This paper attempts to provide a summary of what has been learned about the structure of adsorbed monolayers and about the surface chemical bond from molecular surface science. While the surface chemical bond is less well understood than bonding of molecules in the gas phase or in the solid state, our knowledge of its properties is rapidly accumulating. The information obtained also has great impact on many surface science based technologies, including heterogeneous catalysis and electronic devices. It is hoped that much of the information obtained from studies at solid-gas interfaces can be correlated with molecular behavior at solid-liquid interfaces. 31 references, 42 figures, 1 table

  19. Filter-adsorber aging assessment

    International Nuclear Information System (INIS)

    An aging assessment of high-efficiency particulate (HEPA) air filters and activated carbon gas adsorption units was performed by the Pacific Northwest Laboratory as part of the U.S. Nuclear Regulatory Commission's (USNRC) Nuclear Plant Aging Research (NPAR) Program. This evaluation of the general process in which characteristics of these two components gradually change with time or use included the compilation of information concerning failure experience, stressors, aging mechanisms and effects, and inspection, surveillance, and monitoring methods (ISMM). Stressors, the agents or stimuli that can produce aging degradation, include heat, radiation, volatile contaminants, and even normal concentrations of aerosol particles and gasses. In an experimental evaluation of degradation in terms of the tensile breaking strength of aged filter media specimens, over forty percent of the samples did not meet specifications for new material. Chemical and physical reactions can gradually embrittle sealants and gaskets as well as filter media. Mechanisms that can lead to impaired adsorber performance are associated with the loss of potentially available active sites as a result of the exposure of the carbon to airborne moisture or volatile organic compounds. Inspection, surveillance, and monitoring methods have been established to observe filter pressure drop buildup, check HEPA filters and adsorbers for bypass, and determine the retention effectiveness of aged carbon. These evaluations of installed filters do not reveal degradation in terms of reduced media strength but that under normal conditions aged media can continue to effectively retain particles. However, this degradation may be important when considering the likelihood of moisture, steam, and higher particle loadings during severe accidents and the fact it is probable that the filters have been in use for an extended period

  20. Adsorption of small gas molecules on B36 nanocluster

    Indian Academy of Sciences (India)

    Younes Valadbeigi; Hossein Farrokhpour; Mahmoud Tabrizchi

    2015-11-01

    Adsorption of CO, N2, H2O, O2, H2 and NO molecules on B36 cluster was studied using density functional theory (DFT) with B3LYP functional and 6-311+G(d,p) basis set. Energies, enthalpies and Gibbs free energies of the adsorption processes were calculated. The thermodynamic data showed that the B36 cluster is a good adsorbent only for CO, O2 and NO molecules. The calculated energies of adsorption of N2, H2 O and H2 on the B36 cluster were positive values. CO molecule is adsorbed via the carbon atom more effectively, while the nitrogen atom of NO is adsorbed better than the oxygen atom. Also, when NO and O2 are adsorbed synchronously via both atoms, they dissociate. The edge boron atoms of the B36 cluster showed more reactivity than the inner atoms.

  1. Making More-Complex Molecules Using Superthermal Atom/Molecule Collisions

    Science.gov (United States)

    Shortt, Brian; Chutjian, Ara; Orient, Otto

    2008-01-01

    A method of making more-complex molecules from simpler ones has emerged as a by-product of an experimental study in outer-space atom/surface collision physics. The subject of the study was the formation of CO2 molecules as a result of impingement of O atoms at controlled kinetic energies upon cold surfaces onto which CO molecules had been adsorbed. In this study, the O/CO system served as a laboratory model, not only for the formation of CO2 but also for the formation of other compounds through impingement of rapidly moving atoms upon molecules adsorbed on such cold interstellar surfaces as those of dust grains or comets. By contributing to the formation of increasingly complex molecules, including organic ones, this study and related other studies may eventually contribute to understanding of the origins of life.

  2. Amine-pillared Nanosheet Adsorbents for CO2 Capture Applications

    Science.gov (United States)

    Jiang, Hui

    Amine-functionalized solid adsorbents have gained attention within the last decade for their application in carbon dioxide capture, due to their many advantages such as low energy cost for regeneration, tunable structure, elimination of corrosion problems, and additional advantages. However, one of the challenges facing this technology is to accomplish both high CO 2 capture capacity along with high CO2 diffusion rates concurrently. Current amine-based solid sorbents such as porous materials similar to SBA-15 have large pores diffusion entering molecules; however, the pores become clogged upon amine inclusion. To meet this challenge, our group's solution involves the creation of a new type of material which we are calling-amino-pillared nanosheet (APN) adsorbents which are generated from layered nanosheet precursors. These materials are being proposed because of their unique lamellar structure which exhibits ability to be modified by organic or inorganic pillars through consecutive swelling and pillaring steps to form large mesoporous interlayer spaces. After the expansion of the layer space through swelling and pillaring, the large pore space can be functionalized with amine groups. This selective functionalization is possible by the choice of amine group introduced. Our choice, large amine molecules, do not access the micropore within each layer; however, either physically or chemically immobilized onto the surface of the mesoporous interlayer space between each layer. The final goal of the research is to investigate the ability to prepare APN adsorbents from a model nanoporous layered materials including nanosheets precursor material MCM-22(P) and nanoporous layered silicate material AMH-3. MCM-22(P) contains 2-dimensional porous channels, 6 membered rings (MB) openings perpendicular to the layers and 10 MB channels in the plane of the layers. However, the transport limiting openings (6 MB) to the layers is smaller than CO2 gas molecules. In contrast, AMH-3 has

  3. Organic adsorbates on metal surfaces. PTCDA and NTCDA on AG(110)

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, Afshin

    2010-02-22

    Polyaromatic molecules functionalized with carboxylic groups have served as model systems for the growth of organic semiconducting films on a large variety of substrates. Most non-reactive substrates allow for a growth mode compatible with the bulk phase of the molecular crystal with two molecules in the unit cell, but some more reactive substrates including Ag(111) and Ag(110) can induce substantial changes in the first monolayer (ML). In the specific case of Ag(110), the adsorbate unit cell of both NTCDA and PTCDA resembles a brickwall structure, with a single molecule in the unit cell. From this finding, it can be concluded that the adsorbate-substrate interaction is stronger than typical inter-molecular binding energies in the respective bulk phases. In the present work, the interactions between small Ag(110) clusters and a single NTCDA or PTCDA molecule are investigated with different ab initio techniques. Four major ingredients contribute to the binding between adsorbate and substrate: Directional bonds between Ag atoms in the topmost layer and the oxygen atoms of the molecule, Pauli repulsion between filled orbitals of molecule and substrate, an attractive van-der-Waals interaction, and a negative net charge on the molecule inducing positive image charges in the substrate, resulting therefore in an attractive Coulomb interaction between these opposite charges. As both Hartree-Fock theory and density functional theory with typical gradient-corrected density functional do not contain any long range correlation energy required for dispersion interactions, we compare these approaches with the fastest numerical technique where the leading term of the van-der-Waals interaction is included, i.e. second order Moeller-Plesset theory (MP2). Both Hartree-Fock and density functional theory result in bended optimized geometries where the adsorbate is interacting mainly via the oxygen atoms, with the core of the molecule repelled from the substrate. Only at the MP2 level

  4. Explosive Nucleosynthesis in Hypernovae

    CERN Document Server

    Nakamura, T; Iwamoto, K; Nomoto, K; Hashimoto, M; Hix, W R; Thielemann, F K; Nakamura, Takayoshi; Umeda, Hideyuki; Iwamoto, Koichi; Nomoto, Ken'ichi; Hashimoto, Masa-aki; Thielemann, Friedrich-Karl

    2000-01-01

    We examine the characteristics of nucleosynthesis in 'hypernovae', i.e., supernovae with very large explosion energies ($ \\gsim 10^{52} $ ergs). We carry out detailed nucleosynthesis calculations for these energetic explosions and compare the yields with those of ordinary core-collapse supernovae. We find that both complete and incomplete Si-burning takes place over more extended, lower density regions, so that the alpha-rich freezeout is enhanced in comparison with ordinary supernova nucleosynthesis. In addition, oxygen and carbon burning takes place in more extended, lower density regions than in ordinary supernovae. Therefore, the fuel elements O, C, Al are less abundant while a larger amount of burning products such as Si, S, and Ar are synthesized by oxygen burning. Implications for Galactic chemical evolution and the abundances in metal-poor stars are also discussed.

  5. Complete braided adsorbent for marine testing to demonstrate 3g-U/kg-adsorbent

    Energy Technology Data Exchange (ETDEWEB)

    Janke, Chris [ORNL; Yatsandra, Oyola [ORNL; Mayes, Richard [ORNL; none,; Gill, Gary [PNNL; Li-Jung, Kuo [PNNL; Wood, Jordana [PNNL; Sadananda, Das [ORNL

    2014-04-30

    ORNL has manufactured four braided adsorbents that successfully demonstrated uranium adsorption capacities ranging from 3.0-3.6 g-U/kg-adsorbent in marine testing at PNNL. Four new braided and leno woven fabric adsorbents have also been prepared by ORNL and are currently undergoing marine testing at PNNL.

  6. Explosions in November

    OpenAIRE

    Steinitz, Richard

    2011-01-01

    Explosions in November tells the story of one of Europe’s leading cultural institutions, Huddersfield Contemporary Music Festival (hcmf), through the eyes of its founder and former artistic director, Professor Richard Steinitz. From its modest beginnings in 1978, when winter fog nearly sabotaged the inaugural programme, to today’s internationally renowned event, hcmf has been a pioneering champion of the best in contemporary music. Commissioning new work, reappraising existing legacies an...

  7. Study on preparation of a vovel silica adsorbent and its selective separation applied to genistein

    Directory of Open Access Journals (Sweden)

    Yuqing Zhang

    2008-03-01

    Full Text Available In order to selectively separate genistein from its crude solution, a novel silica adsorbent was prepared using genistein as the template molecule, gamma-aminopropylthriethoxysilane as the functional monomer and tetraethyl orthosilicate as the cross-linker. It was analyzed by the BET, FTIR, TEM characteristics, the static adsorption experiment, and selective adsorption experiment. The results show that the silica adsorbent has high specific area, special selectivity and high adsorption capacity for genistein. It can recognize and bind genistein in aqueous solution, and lots of nanopores distribute on its surface uniformly. It is concluded that both the shape and size of the recognition sites matching the template molecule result in the performance of this adsorbent to bind genistein and that there are strong ionic and hydrogen bond attractions between the phenolic hydroxyl and the -NH2.

  8. Photoinduced surface dynamics of CO adsorbed on a platinum electrode.

    Science.gov (United States)

    Noguchi, Hidenori; Okada, Tsubasa; Uosaki, Kohei

    2006-08-10

    The surface dynamics of adsorbed CO molecules formed by dissociative adsorption of HCHO at a polycrystalline Pt electrode/electrolyte solution interface was studied by picosecond time-resolved sum-frequency generation (TR-SFG) spectroscopy. A SFG peak at 2050-2060 cm(-1) was observed at the Pt electrode in HClO(4) solution containing HCHO at 0-300 mV (vs Ag/AgCl), indicating the formation of adsorbed CO at an atop site of the Pt surface as a result of dissociative adsorption of HCHO. The peak position varied with potential by approximately 33 cm(-1)/V, as previously found in an infrared reflection absorption spectroscopy (IRAS) study. Irradiation of an intense picosecond visible pulse (25 ps, 532 nm) caused an instant intensity decrease and broadening of the CO peak accompanied by the emergence of a new broad peak at approximately 1980 cm(-1) within the time resolution of the system. These results suggest a decrease and increase in the populations of CO adsorbed on atop and bridge sites, respectively, upon visible pump pulse irradiation. PMID:16884215

  9. Explosives signatures and analysis

    Science.gov (United States)

    Fountain, Augustus Way, III; Oyler, Jonathan M.; Ostazeski, Stanley A.

    2008-04-01

    The challenge of sampling explosive materials for various high threat military and civilian operational scenarios requires the community to identify and exploit other chemical compounds within the mixtures that may be available to support stand-off detection techniques. While limited surface and vapor phase characterization of IEDs exist, they are insufficient to guide the future development and evaluation of field deployable explosives detection (proximity and standoff) capabilities. ECBC has conducted a limited investigation of three artillery ammunition types to determine what chemical vapors, if any, are available for sensing; the relative composition of the vapors which includes the more volatile compounds in munitions, i.e., plastersizers and binders; and the sensitivity needed detect these vapors at stand-off. Also in partnership with MIT-Lincoln Laboratory, we performed a background measurement campaign at the National Training Center to determine the baseline ambient amounts and variability of nitrates and nitro-ester compounds as vapors, particulates, and on surfaces; as well as other chemical compounds related to non-energetic explosive additives. Environmental persistence studies in contexts relevant to counter-IED sensing operations, such as surface residues, are still necessary.

  10. Characteristic Research on Evaporated Explosive Film

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The evaporation source of evaporated explosive was designed and improved based on the inherent specialties of explosive. The compatibility of explosives and addition agent with evaporation vessels was analyzed. The influence of substrate temperature on explosive was analyzed, the control method of substrate temperature was suggested. The influences of evaporation rate on formation of explosive film and mixed explosive film were confirmed. Optimum evaporation rate for evaporation explosive and the better method for evaporating mixed explosive were presented. The necessary characteristics of the evaporated explosive film were obtained by the research of the differences between the evaporated explosive and other materials.

  11. A study of surface enhanced Raman scattering for furfural adsorbed on silver surface

    Science.gov (United States)

    Jia, Ting-jian; Li, Peng-wei; Shang, Zhi-guo; Zhang, Ling; He, Ting-chao; Mo, Yu-jun

    2008-02-01

    The normal Raman spectrum (NRS) and the surface enhanced Raman scattering (SERS) spectrum of furfural in silver colloid were recorded and analyzed in this paper. The assignment of these bands to furfural molecules was performed by density functional theory (DFT) calculation. The data of the SERS by comparing with the one of NRS show that furfural molecules are adsorbed on the silver surface via the nonbonding electrons of the carbonyl oxygen.

  12. NOx adsorber and method of regenerating same

    Science.gov (United States)

    Endicott, Dennis L.; Verkiel, Maarten; Driscoll, James J.

    2007-01-30

    New technologies, such as NOx adsorber catalytic converters, are being used to meet increasingly stringent regulations on undesirable emissions, including NOx emissions. NOx adsorbers must be periodically regenerated, which requires an increased fuel consumption. The present disclosure includes a method of regenerating a NOx adsorber within a NOx adsorber catalytic converter. At least one sensor positioned downstream from the NOx adsorber senses, in the downstream exhaust, at least one of NOx, nitrous oxide and ammonia concentrations a plurality of times during a regeneration phase. The sensor is in communication with an electronic control module that includes a regeneration monitoring algorithm operable to end the regeneration phase when a time rate of change of the at least one of NOx, nitrous oxide and ammonia concentrations is after an expected plateau region begins.

  13. Theoretical and experimental study of the vibrational excitations in ethane monolayers adsorbed on graphite (0001) surfaces

    DEFF Research Database (Denmark)

    Hansen, Flemming Yssing; Taub, H.

    1987-01-01

    The collective vibrational excitations of two different crystalline monolayer phases of ethane (C2H6) adsorbed on the graphite (0001) surface have been investigated theoretically and experimentally. The monolayer phases studied are the commensurate 7/8 ×4 structure in which the ethane molecules lie...

  14. Doping of graphene by adsorption of polar molecules at oxidized zigzag edges

    CERN Document Server

    Berashevich, Julia

    2009-01-01

    We have theoretically investigated the electronic and magnetic properties of graphene whose zigzag edges are oxidized. The alteration of these properties by adsorption of $\\mathrm{H_{2}O}$ and $\\mathrm{NH_3}$ molecules have been considered. It was found that the adsorbed molecules form a cluster along the oxidized zigzag edges of graphene due to interaction with the electro-negative oxygen. Graphene tends to donate a charge to the adsorbates through the oxygen atoms and the efficiency of donation depends on the intermolecular distance and on the location of the adsorbed molecules relative to the plane of graphene. It was found that by appropriate selection of the adsorbates, a controllable and gradual growth of $p$-doping in graphene with a variety of adsorbed molecules can be achieved

  15. Inorganic chemically active adsorbents (ICAAs)

    Energy Technology Data Exchange (ETDEWEB)

    Ally, M.R. [Oak Ridge National Lab., TN (United States); Tavlarides, L.

    1997-10-01

    Oak Ridge National Laboratory (ORNL) researchers are developing a technology that combines metal chelation extraction technology and synthesis chemistry. They begin with a ceramic substrate such as alumina, titanium oxide or silica gel because they provide high surface area, high mechanical strength, and radiolytic stability. One preparation method involves silylation to hydrophobize the surface, followed by chemisorption of a suitable chelation agent using vapor deposition. Another route attaches newly designed chelating agents through covalent bonding by the use of coupling agents. These approaches provide stable and selective, inorganic chemically active adsorbents (ICAAs) tailored for removal of metals. The technology has the following advantages over ion exchange: (1) higher mechanical strength, (2) higher resistance to radiation fields, (3) higher selectivity for the desired metal ion, (4) no cation exchange, (5) reduced or no interference from accompanying anions, (6) faster kinetics, and (7) easy and selective regeneration. Target waste streams include metal-containing groundwater/process wastewater at ORNL`s Y-12 Plant (multiple metals), Savannah River Site (SRS), Rocky Flats (multiple metals), and Hanford; aqueous mixed wastes at Idaho National Engineering Laboratory (INEL); and scrubber water generated at SRS and INEL. Focus Areas that will benefit from this research include Mixed Waste, and Subsurface Contaminants.

  16. Enumerating molecules.

    Energy Technology Data Exchange (ETDEWEB)

    Visco, Donald Patrick, Jr. (, . Tennessee Technological University, Cookeville, TN); Faulon, Jean-Loup Michel; Roe, Diana C.

    2004-04-01

    This report is a comprehensive review of the field of molecular enumeration from early isomer counting theories to evolutionary algorithms that design molecules in silico. The core of the review is a detail account on how molecules are counted, enumerated, and sampled. The practical applications of molecular enumeration are also reviewed for chemical information, structure elucidation, molecular design, and combinatorial library design purposes. This review is to appear as a chapter in Reviews in Computational Chemistry volume 21 edited by Kenny B. Lipkowitz.

  17. Imaging and manipulation of a polar molecule oil Ag(111)

    DEFF Research Database (Denmark)

    Lin, Rong; Braun, K.F.; Tang, H.;

    2001-01-01

    A scanning tunneling microscope (STM) was applied to image and laterally manipulate isolated phosphangulene molecules on Ag(111) at 6 K. Atomic-resolution images clearly revealed three characteristic types of appearances (three-lobed, fish and bump shape) for the adsorbed molecules, which could c...

  18. Imaging and manipulation of a polar molecule on Ag(111)

    DEFF Research Database (Denmark)

    Lin, R.; Braun, K.F.; Tang, H.;

    2001-01-01

    A scanning tunneling microscope (STM) was applied to image and laterally manipulate isolated phosphangulene molecules on Ag(111) at 6 K. Atomic-resolution images clearly revealed three characteristic types of appearances (three-lobed, fish and bump shape) for the adsorbed molecules, which could c...

  19. Gas explosions in process pipes

    OpenAIRE

    Kristoffersen, Kjetil

    2004-01-01

    In this thesis, gas explosions inside pipes are considered. Laboratory experiments and numerical simulations are the basis of the thesis. The target of the work was to study gas explosions in pipes and to develop numer- ical models that could predict accidental gas explosions inside pipes. Experiments were performed in circular steel and plexiglass pipes. The steel pipes have an inner diameter of 22.3 mm and lengths of 1, 2, 5 and 11 m. The plexiglass pipe has an inner diame...

  20. PROBABILISTIC MODELING OF EXPLOSIVE LOADING

    OpenAIRE

    Mkrtychev Oleg Vartanovich; Dorozhinskiy Vladimir Bogdanovich

    2012-01-01

    According to existing design standards, explosive loading represents a special type of loading. Explosive loading is, in most cases, local in nature, although it can exceed the loads for which buildings are designed by a dozen of times. The analysis of terrorist attacks with explosives employed demonstrates that charges have a great power and, consequently, a substantial shock wave pressure. Blast effects are predictable with a certain probability. Therefore, we cannot discuss ...

  1. Heat transfer to the adsorbent in solar adsorption cooling device

    Science.gov (United States)

    Pilat, Peter; Patsch, Marek; Papucik, Stefan; Vantuch, Martin

    2014-08-01

    The article deals with design and construction of solar adsorption cooling device and with heat transfer problem in adsorber. The most important part of adsorption cooling system is adsorber/desorber containing adsorbent. Zeolith (adsorbent) type was chosen for its high adsorption capacity, like a coolant was used water. In adsorber/desorber occur, at heating of adsorbent, to heat transfer from heat change medium to the adsorbent. The time required for heating of adsorber filling is very important, because on it depend flexibility of cooling system. Zeolith has a large thermal resistance, therefore it had to be adapted the design and construction of adsorber. As the best shows the tube type of adsorber with double coat construction. By this construction is ensured thin layer of adsorbent and heating is quick in all volume of adsorbent. The process of heat transfer was experimentally measured, but for comparison simulated in ANSYS, too.

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

    Science.gov (United States)

    Maurer, Reinhard J; Ruiz, Victor G; Tkatchenko, Alexandre

    2015-09-14

    A correct description of electronic exchange and correlation effects for molecules in contact with extended (metal) surfaces is a challenging task for first-principles modeling. In this work, we demonstrate the importance of collective van der Waals dispersion effects beyond the pairwise approximation for organic-inorganic systems on the example of atoms, molecules, and nanostructures adsorbed on metals. We use the recently developed many-body dispersion (MBD) approach in the context of density-functional theory [Tkatchenko et al., Phys. Rev. Lett. 108, 236402 (2012) and Ambrosetti et al., J. Chem. Phys. 140, 18A508 (2014)] and assess its ability to correctly describe the binding of adsorbates on metal surfaces. We briefly review the MBD method and highlight its similarities to quantum-chemical approaches to electron correlation in a quasiparticle picture. In particular, we study the binding properties of xenon, 3,4,9,10-perylene-tetracarboxylic acid, and a graphene sheet adsorbed on the Ag(111) surface. Accounting for MBD effects, we are able to describe changes in the anisotropic polarizability tensor, improve the description of adsorbate vibrations, and correctly capture the adsorbate-surface interaction screening. Comparison to other methods and experiment reveals that inclusion of MBD effects improves adsorption energies and geometries, by reducing the overbinding typically found in pairwise additive dispersion-correction approaches. PMID:26374001

  3. States of water adsorbed on perindopril crystals

    Science.gov (United States)

    Stepanov, V. A.; Khmelevskaya, V. S.; Bogdanov, N. Yu.; Gorchakov, K. A.

    2011-10-01

    The relationship between the structural state of adsorbed water, the crystal structure of the substances, and the solubility of the perindopril salt C19H32N2O5 · C4H11N in water was studied by IR spectroscopy and X-ray diffractometry. The high-frequency shift of the stretching vibrations of adsorbed water and the solubility depend on the crystal structure of the drug substance. A reversible chemical reaction occurred between the adsorbed water and the perindopril salt.

  4. Solid state gas sensors for detection of explosives and explosive precursors

    Science.gov (United States)

    Chu, Yun

    combinatorial chemistry techniques were used for catalyst discovery. Specially, a series of tin oxide catalysts with continuous varying composition of palladium were fabricated to screen for the optimum Pd loading to maximize specificity. Experimental results suggested that sensors with a 12 wt.% palladium loading generated the highest sensitivity while a 8 wt.% palladium loading provided greatest selectivity. XPS and XRD were used to study how palladium doping level affects the oxidation state and crystal structure of the nanocomposite catalyst. As with any passive detection system, a necessary theme of this dissertation was the mitigation of false positive. Toward this end, an orthogonal detection system comprised of two independent sensing platforms sharing one catalyst was demonstrated using TATP, 2, 6-DNT and ammonium nitrate as target molecules. The orthogonal sensor incorporated a thermodynamic based sensing platform to measure the heat effect associated with the decomposition of explosive molecules, and a conductometric sensing platform that monitors the change in electrical conductivity of the same catalyst when exposed to the explosive substances. Results indicate that the orthogonal sensor generates an effective response to explosives presented at part per billion level. In addition, with two independent sensing platforms, a built-in redundancy of results could be expected to minimize false positive.

  5. The influence of pH on the structure of adenine monolayers adsorbed at Au(110)/electrolyte interfaces

    Energy Technology Data Exchange (ETDEWEB)

    Bowfield, A.; Smith, C.I.; Mansley, C.P.; Weightman, P. [Department of Physics, Oliver Lodge Laboratory, University of Liverpool, L69 7ZE (United Kingdom)

    2010-08-15

    The pH of the solution is shown to significantly effect the reflection anisotropy spectroscopy (RAS) profiles of adenine adsorbed at Au(110)/electrolyte interfaces. At pH 12.8 the net adsorption is very weak due the formation of negative adenine ions in solution. The sensitivity of the RAS profiles to the pH of the solution is probably due to a change in the geometry of the adsorbed molecules caused by a disruption of the base stacking configuration that is adopted when adenine is adsorbed from solutions at pH 7.1. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  6. Kondo effect in molecules with strong correlations

    Energy Technology Data Exchange (ETDEWEB)

    Kuzmenko, Tetyana [Department of Physics, Ben-Gurion University, P.O. Box 653, Beer-Sheva 84105 (Israel)]. E-mail: tetyana@bgumail.bgu.ac.il; Kikoin, Konstantin [Department of Physics, Ben-Gurion University, P.O. Box 653, Beer-Sheva 84105 (Israel); Avishai, Yshai [Department of Physics, Ben-Gurion University, P.O. Box 653, Beer-Sheva 84105 (Israel)

    2005-04-30

    A theory of Kondo tunneling through molecules adsorbed on metallic substrate is constructed and the underlying physics is exposed. It is shown that in the case of weak chemisorption the sandwich-type molecules manifest a novel type of Kondo effect that has not been observed in magnetically doped bulk metals. The exchange Hamiltonian of these molecules unveils unusual dynamical SO(n) symmetries instead of conventional SU(2) symmetry. These symmetries can be experimentally realized and the specific value of n can be controlled by gate voltage.

  7. Controlled by Distant Explosions

    Science.gov (United States)

    2007-03-01

    VLT Automatically Takes Detailed Spectra of Gamma-Ray Burst Afterglows Only Minutes After Discovery A time-series of high-resolution spectra in the optical and ultraviolet has twice been obtained just a few minutes after the detection of a gamma-ray bust explosion in a distant galaxy. The international team of astronomers responsible for these observations derived new conclusive evidence about the nature of the surroundings of these powerful explosions linked to the death of massive stars. At 11:08 pm on 17 April 2006, an alarm rang in the Control Room of ESO's Very Large Telescope on Paranal, Chile. Fortunately, it did not announce any catastrophe on the mountain, nor with one of the world's largest telescopes. Instead, it signalled the doom of a massive star, 9.3 billion light-years away, whose final scream of agony - a powerful burst of gamma rays - had been recorded by the Swift satellite only two minutes earlier. The alarm was triggered by the activation of the VLT Rapid Response Mode, a novel system that allows for robotic observations without any human intervention, except for the alignment of the spectrograph slit. ESO PR Photo 17a/07 ESO PR Photo 17a/07 Triggered by an Explosion Starting less than 10 minutes after the Swift detection, a series of spectra of increasing integration times (3, 5, 10, 20, 40 and 80 minutes) were taken with the Ultraviolet and Visual Echelle Spectrograph (UVES), mounted on Kueyen, the second Unit Telescope of the VLT. "With the Rapid Response Mode, the VLT is directly controlled by a distant explosion," said ESO astronomer Paul Vreeswijk, who requested the observations and is lead-author of the paper reporting the results. "All I really had to do, once I was informed of the gamma-ray burst detection, was to phone the staff astronomers at the Paranal Observatory, Stefano Bagnulo and Stan Stefl, to check that everything was fine." The first spectrum of this time series was the quickest ever taken of a gamma-ray burst afterglow

  8. Laser machining of explosives

    Science.gov (United States)

    Perry, Michael D.; Stuart, Brent C.; Banks, Paul S.; Myers, Booth R.; Sefcik, Joseph A.

    2000-01-01

    The invention consists of a method for machining (cutting, drilling, sculpting) of explosives (e.g., TNT, TATB, PETN, RDX, etc.). By using pulses of a duration in the range of 5 femtoseconds to 50 picoseconds, extremely precise and rapid machining can be achieved with essentially no heat or shock affected zone. In this method, material is removed by a nonthermal mechanism. A combination of multiphoton and collisional ionization creates a critical density plasma in a time scale much shorter than electron kinetic energy is transferred to the lattice. The resulting plasma is far from thermal equilibrium. The material is in essence converted from its initial solid-state directly into a fully ionized plasma on a time scale too short for thermal equilibrium to be established with the lattice. As a result, there is negligible heat conduction beyond the region removed resulting in negligible thermal stress or shock to the material beyond a few microns from the laser machined surface. Hydrodynamic expansion of the plasma eliminates the need for any ancillary techniques to remove material and produces extremely high quality machined surfaces. There is no detonation or deflagration of the explosive in the process and the material which is removed is rendered inert.

  9. Tenderizing Meat with Explosives

    Science.gov (United States)

    Gustavson, Paul K.; Lee, Richard J.; Chambers, George P.; Solomon, Morse B.; Berry, Brad W.

    2001-06-01

    Investigators at the Food Technology and Safety Laboratory have had success tenderizing meat by explosively shock loading samples submerged in water. This technique, referred to as the Hydrodynamic Pressure (HDP) Process, is being developed to improve the efficiency and reproducibility of the beef tenderization processing over conventional aging techniques. Once optimized, the process should overcome variability in tenderization currently plaguing the beef industry. Additional benefits include marketing lower quality grades of meat, which have not been commercially viable due to a low propensity to tenderization. The simplest and most successful arrangement of these tests has meat samples (50 to 75 mm thick) placed on a steel plate at the bottom of a plastic water vessel. Reported here are tests which were instrumented by Indian Head investigators. Carbon-composite resistor-gauges were used to quantify the shock profile delivered to the surface of the meat. PVDF and resistor gauges (used later in lieu of PVDF) provided data on the pressure-time history at the meat/steel interface. Resulting changes in tenderization were correlated with increasing shock duration, which were provided by various explosives.

  10. Metal-Molecule Contacts: From Adsorption to Charge Transport

    International Nuclear Information System (INIS)

    Full text: Highly ordered monolayers and thin films of electrically active molecules on single crystal metal surfaces are excellent model systems for metal-molecule contacts. They can be used to study fundamental properties of metal-molecule contacts, employing a wide range of surface analytical techniques. In this talk I will give examples of our recent work regarding structure and bonding at the organic-metal interface, interface energetics, and precision measurements of current transport through metal-adsorbed molecules using an STM tip. The adsorption of large organic molecules on metal surfaces is often affected by a sizeable contribution of van der Waals attraction to the interaction energy. This makes theoretical simulations challenging. Precise measurements of structural parameters of adsorbed molecules are therefore important as benchmarks for novel simulation approaches. On the other hand, with a universal theoretical description still missing, empirical rules, such as the scaling of the adsorption height with the substrate work function that was observed for PTCDA on noble metal surfaces, provide important guidelines for our understanding. Apart from the molecule-substrate interaction, intermolecular interactions play an important role. For example, networks of hydrogen bonds can influence the internal geometry of adsorbed molecules and their adsorption height, whereas intermolecular polarization screening can influence their electronic structure. Adsorbed molecules on single-crystal surfaces are also an excellent starting point for precise and well-controlled charge transport experiments through individual molecules, because with an STM they can be contacted at a defined position within the molecule. In this way, the influence of electron correlation on quantum transport can be studied. Finally, we show that if an STM is equipped with a single D2 molecule that is confined in the STM junction, Pauli repulsion is probed and can be used to record images of

  11. New liquid waste control with tannin adsorbent

    International Nuclear Information System (INIS)

    Since 1971, the Mitsubishi Nuclear Fuel Co., Ltd. (MNF) has been fabricating PWR fuels and developing related technology and processes. In the UF6 reconversion lines of MNF, the ammonium diuranate (ADU) process has been operating and the newly developed process of liquid waste treatment was installed last year. The characteristic of this process is to use insoluble tannin adsorbent which has been developed by MNF. The tannin adsorbent is not only an effective means to adsorb heavy metals such as uranium and plutonium but is also easy to incinerate at low temperature. Control of radioactive liquid waste from nuclear facilities is generally implemented by co-precipitation. However, it produces secondary wastes such as noncombustible materials which include radionuclides and it is anticipated that the storage and disposal of those wastes will be at high cost. Those are the reasons why tannin adsorbent has an advantage, and why MNF develops it. (author)

  12. IR investigations of surfaces and adsorbates

    CERN Document Server

    Gwyn, W

    2001-01-01

    Synchrotron infrared reflection-absorption measurements on single crystal metal surfaces with adsorbates have led to the determination of many key parameters related to the bonding vibrational modes and the dynamics of adsorbates. In particular, energy couplings between electrons and adsorbate motion have been shown to be a dominant mechanism on metal surfaces. Excellent agreement has been obtained with calculations for many of the observations, and the synergy between theory and experiment has led to a deeper understanding of the roles of electrons and phonons in determining the properties of interfaces and their roles in phenomena as diverse as friction, lubrication, catalysis and adhesion. Nonetheless, as the experiments are pushed harder, to describe such effects as co-adsorbed systems, disagreements continue to challenge the theory and our comprehension also is still evolving.

  13. New method for the preparation of adsorbent with high adsorption capacity

    Institute of Scientific and Technical Information of China (English)

    WANG Yongjian; LIU Jianfeng; DUO Jia; YU Yaoting

    2005-01-01

    Polyamidoamine (PAMAM) is a type of macro- molecule having a definite chemical structure and a large number of terminal functional groups. The synthetic approach of the adsorbent with high adsorption capacity involved arching of PAMAM onto cellulose beads by reaction with epichlorohydrin. The product thus prepared had a large number of amino groups of 2.94 mmol/g derived from 0.23 mmol/g epoxy groups on cellulose beads. This method presents an effective method for the preparation of high-loading adsorbents.

  14. ADSORBENTS USED IN THE CLEARANCE OF ENDOTOXIN

    Institute of Scientific and Technical Information of China (English)

    YU Mei; LIU Tao; Hou Guanghui; YUAN Zhi

    2003-01-01

    A series of modified poly (methyl methacrylate, PMMA) resins were prepared and compared their adsorption abilities to endotoxin. The results showed that adsorbents, which were grafted with tertiary amine and long spacing arms, had the best adsorption capacities and good blood compatibility, It is hopeful to be used as adsorbent in hemoperfusion for clinical clearance of endotoxin. The influence of original concentration of endotoxin on adsorption and the adsorption mechanism were also investigated.

  15. Mesoporous Silica: A Suitable Adsorbent for Amines

    Directory of Open Access Journals (Sweden)

    Abdollahzadeh-Ghom Sara

    2009-01-01

    Full Text Available Abstract Mesoporous silica with KIT-6 structure was investigated as a preconcentrating material in chromatographic systems for ammonia and trimethylamine. Its adsorption capacity was compared to that of existing commercial materials, showing its increased adsorption power. In addition, KIT-6 mesoporous silica efficiently adsorbs both gases, while none of the employed commercial adsorbents did. This means that KIT-6 Mesoporous silica may be a good choice for integrated chromatography/gas sensing micro-devices.

  16. Behavior of macromolecules in adsorbed layers

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A model for describing the behavior of macromolecules in adsorbed layers is developed by introducing a concept of distribution density of layer thickness U based on stochastic process and probabilistic statistics. The molecular behavior of layers adsorbed on clay particle surfaces is discussed; the random distribution and its statistics of the layer thickness are given by incorporating experimental results with an ionic polyelectrolyte with the molecular weight of 1.08×106 and chain charged density of 0.254.

  17. Dissolved Air Flotation of arsenic adsorbent particles

    Directory of Open Access Journals (Sweden)

    M. Santander

    2015-04-01

    Full Text Available The removal of arsenic from synthetic effluent was studied using the adsorbent particle flotation technique (APF and dissolved air flotation (DAF. A sample of an iron mineral was used as adsorbent particles of arsenic, ferric chloride as coagulant, cationic polyacrylamide (NALCO 9808 as flocculants, and sodium oleate as collector. Adsorption studies to determine the pH influence, contact time, and adsorbent particles concentration on the adsorption of arsenic were carried out along with flotation studies to determine the removal efficiency of adsorbents particles. The results achieved indicate that the adsorption kinetic of arsenic is very rapid and that in range of pH’s from 2 to 7 the adsorption percentages remain constant. The equilibrium conditions were achieved in 60 minutes and about 95% of arsenic was adsorbed when used an adsorbent concentration of 2 g/L and pH 6.3. The maximum adsorption capacity of adsorbent particles was 4.96 mg/g. The mean free energy of adsorption (E was found to be 2.63 kJ/mol, which suggests physisorption. The results of the flotation studies demonstrated that when synthetic effluents with 8.9 mg/L of arsenic were treated under the following experimental conditions; 2 g/L of adsorbent particles, 120 mg/L of Fe(III, 2 mg/L of Nalco 9808, 20 mg/L of sodium oleate, and 40% of recycle ratio in the DAF, it was possible to reach 98% of arsenic removal and 6.3 NTU of residual turbidity in clarified synthetic effluent.

  18. Kaliski's explosive driven fusion experiments

    International Nuclear Information System (INIS)

    An experiment performed by a group in Poland on the production of DD fusion neutrons by purely explosive means is discussed. A method for multiplying shock velocities ordinarily available from high explosives by a factor of ten is described, and its application to DD fusion experiments is discussed

  19. Lidar Detection of Explosives Traces

    Science.gov (United States)

    Bobrovnikov, Sergei M.; Gorlov, Evgeny V.; Zharkov, Victor I.; Panchenko, Yury N.

    2016-06-01

    The possibility of remote detection of traces of explosives using laser fragmentation/laser-induced fluorescence (LF/LIF) is studied. Experimental data on the remote visualization of traces of trinitrotoluene (TNT), hexogen (RDX), trotyl-hexogen (Comp B), octogen (HMX), and tetryl with a scanning lidar detector of traces of nitrogen-containing explosives at a distance of 5 m are presented.

  20. Lidar Detection of Explosives Traces

    OpenAIRE

    Bobrovnikov Sergei M.; Gorlov Evgeny V.; Zharkov Victor I.; Panchenko Yury N.

    2016-01-01

    The possibility of remote detection of traces of explosives using laser fragmentation/laser-induced fluorescence (LF/LIF) is studied. Experimental data on the remote visualization of traces of trinitrotoluene (TNT), hexogen (RDX), trotyl-hexogen (Comp B), octogen (HMX), and tetryl with a scanning lidar detector of traces of nitrogen-containing explosives at a distance of 5 m are presented.

  1. Density functional study of adsorptions of CO2, NO2 and SO2 molecules on Zn(0002) surfaces

    Science.gov (United States)

    Nugraha; Saputro, A. G.; Agusta, M. K.; Yuliarto, B.; Dipojono, H. K.; Maezono, R.

    2016-08-01

    We report on a theoretical study of adsorptions of CO2, NO2 and SO2 molecules on ZnO(0002) surfaces using density functional theory-based (DFT-based) calculations. These adsorptions are done on perfect and defective ZnO(0002) surfaces. We find that all of these molecules are chemically adsorbed on the perfect ZnO(0002) surface. In the presence of Zn vacancy, we find that the surface is only active toward SO2 molecule. On the hydroxylated ZnO(0002) surfaces, CO2 and SO2 molecules can react with the preadsorbed OH molecule to form various adsorbates such as: carboxyl (COOH), bicarbonate (CO3H), sulfonyl hydroxide (SO3H), SO3 and water. However, NO2 molecule cannot react with the pre-adsorbed OH molecule and only physically adsorbed on the surface.

  2. Photochemistry of Nitrate Adsorbed on Mineral Dust

    Science.gov (United States)

    Gankanda, A.; Grassian, V. H.

    2013-12-01

    Mineral dust particles in the atmosphere are often associated with adsorbed nitrate from heterogeneous reactions with nitrogen oxides including HNO3 and NO2. Although nitrate ion is a well-studied chromophore in natural waters, the photochemistry of adsorbed nitrate on mineral dust particles is yet to be fully explored. In this study, wavelength dependence of the photochemistry of adsorbed nitrate on different model components of mineral dust aerosol has been investigated using transmission FTIR spectroscopy. Al2O3, TiO2 and NaY zeolite were used as model systems to represent non-photoactive oxides, photoactive semiconductor oxides and porous materials respectively, present in mineral dust aerosol. In this study, adsorbed nitrate is irradiated with 254 nm, 310 nm and 350 nm narrow band light. In the irradiation with narrow band light, NO2 is the only detectable gas-phase product formed from nitrate adsorbed on Al2O3 and TiO2. The NO2 yield is highest at 310 nm for both Al2O3 and TiO2. Unlike Al2O3 and TiO2, in zeolite, adsorbed nitrate photolysis to nitrite is observed only at 310 nm during narrow band irradiation. Moreover gas phase products were not detected during nitrate photolysis in zeolite at all three wavelengths. The significance of these differences as related to nitrate photochemistry on different mineral dust components will be highlighted.

  3. Nanosensors for trace explosive detection

    Directory of Open Access Journals (Sweden)

    Larry Senesac

    2008-03-01

    Full Text Available Selective and sensitive detection of explosives is very important in countering terrorist threats. Detecting trace explosives has become a very complex and expensive endeavor because of a number of factors, such as the wide variety of materials that can be used as explosives, the lack of easily detectable signatures, the vast number of avenues by which these weapons can be deployed, and the lack of inexpensive sensors with high sensitivity and selectivity. High sensitivity and selectivity, combined with the ability to lower the deployment cost of sensors using mass production, is essential in winning the war on explosives-based terrorism. Nanosensors have the potential to satisfy all the requirements for an effective platform for the trace detection of explosives.

  4. Assessing nuclear explosions

    Science.gov (United States)

    Smith, Joseph V.

    The all-Union session on the Geophysical and Geochemical Consequences of Nuclear Explosions at the 1983 AGU Fall Meeting attracted a large audience, and many were unable to find a seat or standing room. The speakers and questioners emphasized the complexity of the processes and the need to extend the computer models. In particular, the global-circulation models presented byscientists from the National Center for Atmospheric Research showed that smoke/dust clouds should cause major changes in the weather systems with great contrast between the temperature perturbations over oceanic, coastal, and continental regions. Important developments in the models and conclusions can be expected over the next few years as AGU members from many disciplines contribute their skills.

  5. Nucleosynthesis in stellar explosions

    Energy Technology Data Exchange (ETDEWEB)

    Woosley, S.E.; Axelrod, T.S.; Weaver, T.A.

    1983-01-01

    The final evolution and explosion of stars from 10 M/sub solar/ to 10/sup 6/ M/sub solar/ are reviewed with emphasis on factors affecting the expected nucleosynthesis. We order our paper in a sequence of decreasing mass. If, as many suspect, the stellar birth function was peaked towards larger masses at earlier times (see e.g., Silk 1977; but also see Palla, Salpeter, and Stahler 1983), this sequence of masses might also be regarded as a temporal sequence. At each stage of Galactic chemical evolution stars form from the ashes of preceding generations which typically had greater mass. A wide variety of Type I supernova models, most based upon accreting white dwarf stars, are also explored using the expected light curves, spectra, and nucleosynthesis as diagnostics. No clearly favored Type I model emerges that is capable of simultaneously satisfying all three constraints.

  6. Nucleosynthesis in stellar explosions

    International Nuclear Information System (INIS)

    The final evolution and explosion of stars from 10 M/sub solar/ to 106 M/sub solar/ are reviewed with emphasis on factors affecting the expected nucleosynthesis. We order our paper in a sequence of decreasing mass. If, as many suspect, the stellar birth function was peaked towards larger masses at earlier times (see e.g., Silk 1977; but also see Palla, Salpeter, and Stahler 1983), this sequence of masses might also be regarded as a temporal sequence. At each stage of Galactic chemical evolution stars form from the ashes of preceding generations which typically had greater mass. A wide variety of Type I supernova models, most based upon accreting white dwarf stars, are also explored using the expected light curves, spectra, and nucleosynthesis as diagnostics. No clearly favored Type I model emerges that is capable of simultaneously satisfying all three constraints

  7. Mixing in explosions

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, A.L.

    1993-12-01

    Explosions always contain embedded turbulent mixing regions, for example: boundary layers, shear layers, wall jets, and unstable interfaces. Described here is one particular example of the latter, namely, the turbulent mixing occurring in the fireball of an HE-driven blast wave. The evolution of the turbulent mixing was studied via two-dimensional numerical simulations of the convective mixing processes on an adaptive mesh. Vorticity was generated on the fireball interface by baroclinic effects. The interface was unstable, and rapidly evolved into a turbulent mixing layer. Four phases of mixing were observed: (1) a strong blast wave phase; (2) and implosion phase; (3) a reshocking phase; and (4) an asymptotic mixing phase. The flowfield was azimuthally averaged to evaluate the mean and r.m.s. fluctuation profiles across the mixing layer. The vorticity decayed due to a cascade process. This caused the corresponding enstrophy parameter to increase linearly with time -- in agreement with homogeneous turbulence calculations of G.K. Batchelor.

  8. Adsorption Geometry Determination of Single Molecules by Atomic Force Microscopy

    OpenAIRE

    Schuler, Bruno; Liu, Wei; Tkatchenko, Alexandre; Moll, Nikolaj; Meyer, Gerhard; Mistry, Anish; Fox, David; GROSS, Leo

    2013-01-01

    We measured the adsorption geometry of single molecules with intramolecular resolution using noncontact atomic force microscopy with functionalized tips. The lateral adsorption position was determined with atomic resolution, adsorption height differences with a precision of 3 pm, and tilts of the molecular plane within 0.2 degrees. The method was applied to five pi-conjugated molecules, including three molecules from the olympicene family, adsorbed on Cu(111). For the olympicenes, we found th...

  9. Adsorption and oxidation of formaldehyde on a polycrystalline Pt film electrode: An in situ IR spectroscopy search for adsorbed reaction intermediates.

    Science.gov (United States)

    Jusys, Zenonas; Behm, R Jürgen

    2014-01-01

    As part of a mechanistic study of the electrooxidation of C1 molecules we have systematically investigated the dissociative adsorption/oxidation of formaldehyde on a polycrystalline Pt film electrode under experimental conditions optimizing the chance for detecting weakly adsorbed reaction intermediates. Employing in situ IR spectroscopy in an attenuated total reflection configuration (ATR-FTIRS) with p-polarized IR radiation to further improve the signal-to-noise ratio, and using low reaction temperatures (3 °C) and deuterium substitution to slow down the reaction kinetics and to stabilize weakly adsorbed reaction intermediates, we could detect an IR absorption band at 1660 cm(-1) characteristic for adsorbed formyl intermediates. This assignment is supported by an isotope shift in wave number. Effects of temperature, potential and deuterium substitution on the formation and disappearance of different adsorbed species (COad, adsorbed formate, adsorbed formyl), are monitored and quantified. Consequences on the mechanism for dissociative adsorption and oxidation of formaldehyde are discussed.

  10. Self-sorting in two-dimensional assemblies of simple chiral molecules

    OpenAIRE

    Woszczyk, A.; Szabelski, P.

    2016-01-01

    Structural modification of adsorbed overlayers by means of external factors is an important objective in the fabrication of stimuli-responsive materials with adjustable physicochemical properties. In this contribution we present a coarse-grained Monte Carlo model of the confinement-induced chiral self-sorting of hockey stick-shaped enantiomers adsorbed on a triangular lattice. It is assumed that the adsorbed overlayer consists of "normal" molecules that are capable of adopting any of the six ...

  11. Optical detection of explosives: spectral signatures for the explosive bouquet

    Science.gov (United States)

    Osborn, Tabetha; Kaimal, Sindhu; Causey, Jason; Burns, William; Reeve, Scott

    2009-05-01

    Research with canines suggests that sniffer dogs alert not on the odor from a pure explosive, but rather on a set of far more volatile species present in an explosive as impurities. Following the explosive trained canine example, we have begun examining the vapor signatures for many of these volatile impurities utilizing high resolution spectroscopic techniques in several molecular fingerprint regions. Here we will describe some of these high resolution measurements and discuss strategies for selecting useful spectral signature regions for individual molecular markers of interest.

  12. Insight into the adsorption of PPCPs by porous adsorbents: Effect of the properties of adsorbents and adsorbates.

    Science.gov (United States)

    Zhu, Zengyin; Xie, Jiawen; Zhang, Mancheng; Zhou, Qing; Liu, Fuqiang

    2016-07-01

    Adsorption is an efficient method for removal of pharmaceuticals and personal care products (PPCPs). Magnetic resins are efficient adsorbents for water treatment and exhibit potential for PPCP removal. In this study, the magnetic hypercrosslinked resin Q100 was used for adsorption of PPCPs. The adsorption behavior of this resin was compared with those of two activated carbons, namely, Norit and F400D. Norit exhibited the fastest adsorption kinetics, followed by Q100. Norit featured a honeycomb shape and long-range ordered pore channels, which facilitated the diffusion of PPCPs. Moreover, the large average pore size of Q100 reduced diffusion resistance. The adsorbed amounts of 11 PPCPs on the three adsorbents increased with increasing adsorbate hydrophobicity. For Q100, a significant linear correlation was observed between the adsorption performance for PPCPs and hydrophobicity (logD value) of adsorbates (R(2) = 0.8951); as such, PPCPs with high logD values (>1.69) could be efficiently removed. Compared with those of Norit and F400D, the adsorption performance of Q100 was less affected by humic acid because of the dominant hydrophobic interaction. Furthermore, Q100 showed improved regeneration performance, which renders it promising for PPCP removal in practical applications. PMID:27131811

  13. Novel Fiber-Based Adsorbent Technology; FINAL

    International Nuclear Information System (INIS)

    The overall of this Department of Energy (DOE) Phase II SBIR program was to develop a new class of highly robust fiber-based adsorbents for recovery of heavy metals from aqueous waste-streams. The fiber-based adsorbents,when commercialized,will be used for clean up metals in aqueous waste-streams emanating from DOE facilities,industry,mining,and groundwater-cleanup operations.The amount of toxic waste released by these streams is of great significance.The U.S.Environment Protection Agency (EPA) reports that in 1990 alone,4.8 billion pounds of toxic chemicals were released into the environment.Of this waste,the metals-containing waste was the second largest contributor,representing 569 million pounds. This report presents the results of the Phase II program,which successfully synthesized noval fiber-based adsorbents for the removal of Group 12 metals(i.e.mercury),Group 14 metals (lead),and Group 10 metals(platinum and palladium) from contaminated groundwater and industrial waste streams.These fiber-based adsorbents are ideally suited for the recovery of metal ions from aqueous waste streams presently not treatable due to the degrading nature of corrosive chemicals or radioactive components in the feed stream. The adsorbents developed in this program rely on chemically resistant and robust carbon fibers and fabrics as supports for metal-ion selective ligands.These adsorbents demonstrate loading capacities and selectivities for metal ions exceeding those of conventional ion-exchange resins.The adsorbents were also used to construct filter modules that demonstrate minimal fouling,minimal compaction,chemical and physical robustness,and regeneration of metal loading capacity without loss of performance

  14. Theory and simulation of epitaxial rotation. Light particles adsorbed on graphite

    DEFF Research Database (Denmark)

    Vives, E.; Lindgård, P.-A.

    1993-01-01

    We present a theory and Monte Carlo simulations of adsorbed particles on a corrugated substrate. We have focused on the case of rare gases and light molecules, H-2 and D2, adsorbed on graphite. The competition between the particle-particle and particle-substrate interactions gives rise...... between the commensurate and incommensurate phase for the adsorbed systems. From our simulations and our theory, we are, able to understand the gamma phase of D2 as an ordered phase stabilized by disorder. It can be described as a 2q-modulated structure. In agreement with the experiments, we have also...... found a modulated 4 x 4 structure. Energy, structure-factor intensities, peak positions, and epitaxial rotation angles as a function of temperature and coverage have been determined from the simulations. Good agreement with theory and experimental data is found....

  15. Explosive signatures: Pre & post blast

    Science.gov (United States)

    Bernier, Evan Thomas

    Manuscripts 1 and 2 of this dissertation both involve the pre-blast detection of trace explosive material. The first manuscript explores the analysis of human hair as an indicator of exposure to explosives. Field analysis of hair for trace explosives is quick and non-invasive, and could prove to be a powerful linkage to physical evidence in the form of bulk explosive material. Individuals tested were involved in studies which required handling or close proximity to bulk high explosives such as TNT, PETN, and RDX. The second manuscript reports the results of research in the design and application of canine training aids for non-traditional, peroxide-based explosives. Organic peroxides such as triacetonetriperoxide (TATP) and hexamethylenetriperoxidediamine (HMTD) can be synthesized relatively easily with store-bought ingredients and have become popular improvised explosives with many terrorist groups. Due to the hazards of handling such sensitive compounds, this research established methods for preparing training aids which contained safe quantities of TATP and HMTD for use in imprinting canines with their characteristic odor. Manuscripts 3 and 4 of this dissertation focus on research conducted to characterize pipe bombs during and after an explosion (post-blast). Pipe bombs represent a large percentage of domestic devices encountered by law enforcement. The current project has involved the preparation and controlled explosion of over 90 pipe bombs of different configurations in order to obtain data on fragmentation patterns, fragment velocity, blast overpressure, and fragmentation distance. Physical data recorded from the collected fragments, such as mass, size, and thickness, was correlated with the relative power of the initial device. Manuscript 4 explores the microstructural analysis of select pipe bomb fragments. Shock-loading of the pipe steel led to plastic deformation and work hardening in the steel grain structure as evidenced by optical microscopy and

  16. Radiologic diagnosis of explosion casualties.

    Science.gov (United States)

    Eastridge, Brian J; Blackbourne, Lorne; Wade, Charles E; Holcomb, John B

    2008-01-01

    The threat of terrorist events on domestic soil remains an ever-present risk. Despite the notoriety of unconventional weapons, the mainstay in the armament of the terrorist organization is the conventional explosive. Conventional explosives are easily weaponized and readily obtainable, and the recipes are widely available over the Internet. According to the US Department of State and the Federal Bureau of Investigation, over one half of the global terrorist events involve explosions, averaging two explosive events per day worldwide in 2005 (Terrorism Research Center. Available at www.terrorism.com. Accessed April 1, 2007). The Future of Emergency Care in the United States Health System: Emergency Medical Services at the Crossroads, published by the Institute of Medicine, states that explosions were the most common cause of injuries associated with terrorism (Institute of Medicine Report: The Future of Emergency Care in the United States Health System: Emergency Medical Services at the Crossroads. Washington DC: National Academic Press, 2007). Explosive events have the potential to inflict numerous casualties with multiple injuries. The complexity of this scenario is exacerbated by the fact that few providers or medical facilities have experience with mass casualty events in which human and material resources can be rapidly overwhelmed. Care of explosive-related injury is based on same principles as that of standard trauma management paradigms. The basic difference between explosion-related injury and other injury mechanisms are the number of patients and multiplicity of injuries, which require a higher allocation of resources. With this caveat, the appropriate utilization of radiology resources has the potential to impact in-hospital diagnosis and triage and is an essential element in optimizing the management of the explosive-injured patients. PMID:19069034

  17. Energetic lanthanide complexes: coordination chemistry and explosives applications

    International Nuclear Information System (INIS)

    Metals are generally added to organic molecular explosives in a heterogeneous composite to improve overall heat and energy release. In order to avoid creating a mixture that can vary in homogeneity, energetic organic molecules can be directly bonded to high molecular weight metals, forming a single metal complex with Angstrom-scale separation between the metal and the explosive. To probe the relationship between the structural properties of metal complexes and explosive performance, a new series of energetic lanthanide complexes has been prepared using energetic ligands such as NTO (5-nitro-2,4-dihydro-1,2,4-triazole-3-one). These are the first examples of lanthanide NTO complexes where no water is coordinated to the metal, demonstrating novel control of the coordination environment. The complexes have been characterized by X-ray crystallography, NMR and IR spectroscopies, photoluminescence, and sensitivity testing. The structural and energetic properties are discussed in the context of enhanced blast effects and detection. Cheetah calculations have been performed to fine-tune physical properties, creating a systematic method for producing explosives with 'tailor made' characteristics. These new complexes will be benchmarks for further study in the field of metalized high explosives.

  18. Influence of Adsorbed Water on the Oxygen Evolution Reaction on Oxides

    DEFF Research Database (Denmark)

    Siahrostami, Samira; Vojvodic, Aleksandra

    2015-01-01

    We study the interface between adsorbed water and stoichiometric, defect-free (110) rutile oxide surfaces of TiO2, RuO2, and IrO2 in order to understand how water influences the stabilities of the intermediates of the oxygen evolution reaction (OER). In our model the water is treated as explicitly...... adsorbed H2O molecules, which are found to form two-dimensional water chains (layers) on all investigated oxide surfaces. The first chain formed by the most strongly bound H2O molecules is adsorbed on the 5-fold coordinated surface metal atoms. The second chain is composed of less strongly bound H2O...... molecules binding to bridging oxygens. The third chain interacts weakly and predominantly with the H2O molecules of the second layer, resembling bulk water. We find that the stability of the water layer close to the oxide surface is almost the same as the one found on flat metal surfaces, such as the Pt(111...

  19. Defluoridization Using a Natural Adsorbent, Strychnos Potatorum

    Directory of Open Access Journals (Sweden)

    S.Rayappan

    2014-10-01

    Full Text Available The study assessed the suitability of low-cost natural adsorbent to effectively remediate fluoride contaminated water. The removal of fluoride from aqueous solution by using Strychnos Potatorum was studied in batch technique. Influence of pH, adsorbent dose, contact time, co ions, speed and initial concentration on the adsorption were investigated. The maximum removal of fluoride ion was obtained at pH 7. The removal of fluoride was expressed with Langmuir and Freundlich isotherm. It was found that the sufficient time for adsorption equilibrium of fluoride ion was 1 hour. The removal of fluoride ions was maximum for the adsorbent dosage of SP is 50mg/50ml. The fluoride adsorption was maximum at 60minutes. The adsorption of F- ion was maximum in the shaking speed of 120 rpm. The presence of interfering ions such as nitrate and carbonate showed positive effect while sulphate and chloride showed little negative effect and phosphate showed high negative effect for the adsorbent. The optimum initial fluoride concentration for SP adsorbent was 1mg/50ml.

  20. The application of single particle aerosol mass spectrometry for the detection and identification of high explosives and chemical warfare agents

    Energy Technology Data Exchange (ETDEWEB)

    Martin, Audrey Noreen [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2006-01-01

    Single Particle Aerosol Mass Spectrometry (SPAMS) was evaluated as a real-time detection technique for single particles of high explosives. Dual-polarity time-of-flight mass spectra were obtained for samples of 2,4,6-trinitrotoluene (TNT), 1,3,5-trinitro-1,3,5-triazinane (RDX), and pentaerythritol tetranitrate (PETN); peaks indicative of each compound were identified. Composite explosives, Comp B, Semtex 1A, and Semtex 1H were also analyzed, and peaks due to the explosive components of each sample were present in each spectrum. Mass spectral variability with laser fluence is discussed. The ability of the SPAMS system to identify explosive components in a single complex explosive particle (~1 pg) without the need for consumables is demonstrated. SPAMS was also applied to the detection of Chemical Warfare Agent (CWA) simulants in the liquid and vapor phases. Liquid simulants for sarin, cyclosarin, tabun, and VX were analyzed; peaks indicative of each simulant were identified. Vapor phase CWA simulants were adsorbed onto alumina, silica, Zeolite, activated carbon, and metal powders which were directly analyzed using SPAMS. The use of metal powders as adsorbent materials was especially useful in the analysis of triethyl phosphate (TEP), a VX stimulant, which was undetectable using SPAMS in the liquid phase. The capability of SPAMS to detect high explosives and CWA simulants using one set of operational conditions is established.

  1. Heterogeneous radiolysis of HCN adsorbed on a solid surface

    Energy Technology Data Exchange (ETDEWEB)

    Colin-Garcia, M.; Ortega-Gutierrez, F. [Instituto de Geologia, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, 04510 Mexico D.F. (Mexico); Ramos-Bernal, S. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, 04510 Mexico D.F. (Mexico); Negron-Mendoza, A., E-mail: negron@nucleares.unam.m [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Ciudad Universitaria, 04510 Mexico D.F. (Mexico)

    2010-07-21

    Hydrogen cyanide is a key molecule for chemical evolution studies because, when it is exposed to different sources of energy, it forms various compounds of biological importance. To understand the role of minerals in chemical evolution, a series of experiments was performed. First, the adsorption capacity of HCN on different surface minerals was studied; the results show that HCN is readily adsorbed onto the solids proposed (zeolite, serpentine, dolomite, and sodium montmorillonite), in particular zeolite and montmorillonite. Second, the radiolysis of HCN adsorbed on olivine (as an example of a mineral surface) was also followed; it was found that the rate of HCN decomposition by gamma irradiation is enhanced in the presence of the solid. The third series of studies show that organic material was produced in high abundance from HCN at high radiation doses. The radiolytic products included gases (CO{sub 2}, NH{sub 4}, and CO) and oligomeric materials that release carboxylic acids (succinic, malonic, citric, and tricarballylic acids) and amino acids upon acid hydrolysis. These experiments suggest that minerals could have participated actively in chemical evolution processes.

  2. Contact and friction of nanoasperities: effects of adsorbed monolayers.

    Science.gov (United States)

    Cheng, Shengfeng; Luan, Binquan; Robbins, Mark O

    2010-01-01

    Molecular dynamics simulations are used to study contact between a rigid, nonadhesive, and spherical tip with radius of order 30 nm and a flat elastic substrate covered with a fluid monolayer of adsorbed chain molecules. Previous studies of bare surfaces showed that the atomic scale deviations from a sphere that are present on any tip constructed from discrete atoms lead to significant deviations from continuum theory and dramatic variability in friction forces. Introducing an adsorbed monolayer leads to larger deviations from continuum theory but decreases the variations between tips with different atomic structure. Although the film is fluid, it remains in the contact and behaves qualitatively like a thin elastic coating except for certain tips at high loads. Measures of the contact area based on the moments or outer limits of the pressure distribution and on counting contacting atoms are compared. The number of tip atoms making contact during a time interval Deltat grows as a power of Deltat when the film is present and as the logarithm of Deltat for bare surfaces. Friction is measured by displacing the tip at a constant velocity or pulling the tip with a spring. Both static and kinetic friction rise linearly with load at small loads. Transitions in the state of the film lead to nonlinear behavior at large loads. The friction is less clearly correlated with contact area than load. PMID:20365427

  3. Process for producing zeolite adsorbent and process for treating radioactive liquid waste with the zeolite adsorbent

    International Nuclear Information System (INIS)

    Zeolite is contacted with an aqueous solution containing at least one of copper, nickel, cobalt, manganese and zinc salts, preferably copper and nickel salts, particularly preferably copper salt, in such a form as sulfate, nitrate, or chloride, thereby adsorbing the metal on the zeolite in its pores by ion exchange, then the zeolite is treated with a water-soluble ferrocyanide compound, for example, potassium ferrocyanide, thereby forming metal ferrocyanide on the zeolite in its pores. Then, the zeolite is subjected to ageing treatment, thereby producing a zeolite adsorbent impregnated with metal ferrocyanide in the pores of zeolite. The adsorbent can selectively recover cesium with a high percent cesium removal from a radioactive liquid waste containing at least radioactive cesium, for example, a radioactive liquid waste containing cesium and such coexisting ions as sodium, magnesium, calcium and carbonate ions at the same time at a high concentration. The zeolite adsorbent has a stable adsorbability for a prolonged time

  4. Active explosion barrier performance against methane and coal dust explosions

    Institute of Scientific and Technical Information of China (English)

    J J L du Plessis

    2015-01-01

    Preventing the propagation of methane or coal dust explosions through the use of active explosion-suppression systems remains one of the most underutilised explosion controls in underground coal mines. As part of the effort to develop better technologies to safeguard mines, the use of active barrier systems was investigated at Kloppersbos in South Africa. The system is designed to meet the requirements of the European Standard (EN 14591-4 2007) as well as the Mine Safety Standardisation in the Ministry of Coal Industry, Coal Industrial l Standard of the Peoples Republic of China (MT 694-1997). From the tests conducted, it can be concluded that the ExploSpot System was successful in stopping flame propagation for both methane and methane and coal dust hybrid explosions when ammonium phosphate powder was used as the suppression material. The use of this barrier will provide coal mine management with an additional explosion control close to the point of ignition and may find application within longwall faces further protecting mines against the risk of an explosion propagating throughout a mine.

  5. THERMODYNAMIC STUDY OF ADSORPTION OF PHENOLIC COMPOUNDS FROM AQUEOUS SOLUTION BY A WATER-COMPATIBLE HYPERCROSSLINKED POLYMERIC ADSORBENT

    Institute of Scientific and Technical Information of China (English)

    Ai-min Li; Hai-suo Wu; Quan-xing Zhang; Gen-cheng Zhang; Chao Long; Zheng-hao Fei; Fu-qiang Liu; Jin-long Chen

    2004-01-01

    Equilibrium data for the adsorption of phenolic compounds, i.e., phenol, p-cresol, p-chlorophenol and pnitrophenol from aqueous solutions by a water-compatible hypercrosslinked polymeric adsorbent (NJ-8) within temperature range of 283-323 K were obtained and correlated with a Freundlich-type of isotherm equation, so that equilibrium constants KF and n were obtained. The capacities of equilibrium adsorption for all the four phenolic compounds on the NJ-8 from aqueous solutions are around 2 times as high as those of Amberlite XAD-4, which may be attributed to the unusual micropore structure and the partial polarity on the network. The values of the enthalpy (always negative) are indicative of an exothermic process, which manifests the adsorption of all the four phenolic compounds on the two polymeric adsorbents to be a process of physical adsorption. The negative values of free energy change show that the solute is more concentrated on the adsorbent than in the bulk solution. The absolute free energy values of adsorption for NJ-8 are always higher than those for Amberlite XAD-4, which indicates that phenolic compounds are preferentially adsorbed on NJ-8. The negative values of the adsorption entropy are consistent with the restricted mobilities of adsorbed molecules of phenolic compounds as compared with the molecules in solution. The adsorption entropy values of phenolic compounds for NJ-8 are lower than those for Amberlite XAD-4, which means the micropores of NJ-8 require more orderly arranged adsorbate.

  6. Dissecting the Wake of a Supernova Explosion

    Science.gov (United States)

    2007-01-01

    The elements and molecules that flew out of the Cassiopeia A star when it exploded about 300 years ago can be seen clearly for the first time in this plot of data, called a spectrum, taken by NASA's Spitzer Space Telescope. The spectrum, which was created by splitting light into its basic components, reveals the composition of gas and dust that were synthesized in the explosion. It also provides some of the best evidence yet that stellar explosions, called supernovae, were a significant source of fresh dust in the very young universe. Prior to these observations, nobody was certain where this early dust the same dust that ultimately made its way into future stars, planets and people came from. One of the most interesting features of the plot is a bump labeled 'Cassiopeia A dust feature.' This bump is actually the signature of a collection of dust composed of proto-silicates, silicon dioxide and iron oxide. The spectrum reveals that the brightness of the dust feature is correlated to that of argon gas (yellow vertical line at left), known to have been expelled and synthesized during the star's explosion. The fact that the dust is associated with the expelled gas, or ejecta, tells astronomers that this supernova manufactured new dust. Each of the three lines of this plot represents a different layer of the supernova remnant, with the top yellow and red line being the outermost layer. Similar correlations between gas and dust are also seen in the middle layer (green line). For example, neon gas correlates with dust composed of carbon and aluminum oxide.

  7. Photochemical dynamics of surface oriented molecules

    International Nuclear Information System (INIS)

    The period 8/01/91-7/31/92 is the first year of a new project titled ''Photochemical Dynamics of Surface Oriented Molecules'', initiated with DOE Support. The main objective of this project is to understand the dynamics of elementary chemical reactions by studying photochemical dynamics of surface-oriented molecules. In addition, the mechanisms of photon-surface interactions need to be elucidated. The strategy is to carry out experiments to measure the translational energy distribution, as a function of the angle from the surface normal, of the photoproducts by time-of-flight (TOF) technique by varying the photon wavelength, intensity, polarization, and pulse duration. By choosing adsorbates with different bonding configuration, the effects of adsorbate orientation on surface photochemical dynamics can be studied

  8. Spontaneous Symmetry Breaking in Metal Adsorbed Graphene Sheets

    CERN Document Server

    Jalbout, A F

    2012-01-01

    Graphene has received a great deal of attention and this has more recently extended to boron nitride sheets (BNS) with a similar structure. Both have hexagonal lattices and it is only the alternation of atoms in boron nitride, which changes the symmetry structure. This difference can for example be seen in the mean field equations, which for the corners of the Brillouin Zone are Dirac equations. For the case of graphene (equal atoms) we have the equation for massless particles, while for Boron Nitride has a finite gap and is more near a Dirac equation with mass near this gap.. Carbon structures in general and in particular also graphene can adsorb electron donors, such as alkaline atoms or molecules with a dipole moment. Typically these atoms and the dipoles can only attach in the sense to donate electron density. Some results for small sheet like structures are available.

  9. Explosive Contagion in Networks

    Science.gov (United States)

    Gómez-Gardeñes, J.; Lotero, L.; Taraskin, S. N.; Pérez-Reche, F. J.

    2016-01-01

    The spread of social phenomena such as behaviors, ideas or products is an ubiquitous but remarkably complex phenomenon. A successful avenue to study the spread of social phenomena relies on epidemic models by establishing analogies between the transmission of social phenomena and infectious diseases. Such models typically assume simple social interactions restricted to pairs of individuals; effects of the context are often neglected. Here we show that local synergistic effects associated with acquaintances of pairs of individuals can have striking consequences on the spread of social phenomena at large scales. The most interesting predictions are found for a scenario in which the contagion ability of a spreader decreases with the number of ignorant individuals surrounding the target ignorant. This mechanism mimics ubiquitous situations in which the willingness of individuals to adopt a new product depends not only on the intrinsic value of the product but also on whether his acquaintances will adopt this product or not. In these situations, we show that the typically smooth (second order) transitions towards large social contagion become explosive (first order). The proposed synergistic mechanisms therefore explain why ideas, rumours or products can suddenly and sometimes unexpectedly catch on.

  10. Disaster management following explosion.

    Science.gov (United States)

    Sharma, B R

    2008-01-01

    Explosions and bombings remain the most common deliberate cause of disasters involving large numbers of casualties, especially as instruments of terrorism. These attacks are virtually always directed against the untrained and unsuspecting civilian population. Unlike the military, civilians are poorly equipped or prepared to handle the severe emotional, logistical, and medical burdens of a sudden large casualty load, and thus are completely vulnerable to terrorist aims. To address the problem to the maximum benefit of mass disaster victims, we must develop collective forethought and a broad-based consensus on triage and these decisions must reach beyond the hospital emergency department. It needs to be realized that physicians should never be placed in a position of individually deciding to deny treatment to patients without the guidance of a policy or protocol. Emergency physicians, however, may easily find themselves in a situation in which the demand for resources clearly exceeds supply and for this reason, emergency care providers, personnel, hospital administrators, religious leaders, and medical ethics committees need to engage in bioethical decision-making. PMID:18522253

  11. Furball Explosive Breakout Test

    Energy Technology Data Exchange (ETDEWEB)

    Carroll, Joshua David [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-05

    For more than 30 years the Onionskin test has been the primary way to study the surface breakout of a detonation wave. Currently the Onionskin test allows for only a small, one dimensional, slice of the explosive in question to be observed. Asymmetrical features are not observable with the Onionskin test and its one dimensional view. As a result, in 2011, preliminary designs for the Hairball and Furball were developed then tested. The Hairball used shorting pins connected to an oscilloscope to determine the arrival time at 24 discrete points. This limited number of data points, caused by the limited number of oscilloscope channels, ultimately led to the Hairball’s demise. Following this, the Furball was developed to increase the number of data points collected. Instead of shorting pins the Furball uses fiber optics imaged by a streak camera to determine the detonation wave arrival time for each point. The original design was able to capture the detonation wave’s arrival time at 205 discrete points with the ability to increase the number of data points if necessary.

  12. The Cambrian explosion.

    Science.gov (United States)

    Briggs, Derek E G

    2015-10-01

    The sudden appearance of fossils that marks the so-called 'Cambrian explosion' has intrigued and exercised biologists since Darwin's time. In On the Origin of Species, Darwin made it clear that he believed that ancestral forms 'lived long before' their first fossil representatives. While he considered such an invisible record necessary to explain the level of complexity already seen in the fossils of early trilobites, Darwin was at a loss to explain why there were no corresponding fossils of these earlier forms. In chapter 9 of the Origin, entitled 'On the imperfection of the geological record', he emphasized the 'poorness of our palaeontological collections' and stated categorically that 'no organism wholly soft can be preserved'. Fortunately much has been discovered in the last 150 years, not least multiple examples of Cambrian and Precambrian soft-bodied fossils. We now know that the sudden appearance of fossils in the Cambrian (541-485 million years ago) is real and not an artefact of an imperfect fossil record: rapid diversification of animals coincided with the evolution of biomineralized shells. And although fossils in earlier rocks are rare, they are not absent: their rarity reflects the low diversity of life at this time, as well as the low preservation potential of Precambrian organisms (see Primer by Butterfield, in this issue). PMID:26439348

  13. INFLUENCE OF ADSORBED AND DISSOLVED CARBOXYMETHYL CELLULOSE ON FIBRE SUSPENSION DISPERSING, DEWATERABILITY, AND FINES RETENTION

    Directory of Open Access Journals (Sweden)

    Henrikki Liimatainen

    2009-02-01

    Full Text Available The effect of adsorbed and soluble carboxymethyl cellulose (CMC on dispersing, dewaterability, and fines retention of pulp fibre suspensions was investigated. CMC was added to a suspension in the presence of electrolytes, causing its adsorption to the fibre surfaces, or to a suspension without electrolytes, so that it stayed in the liquid phase. Both the CMC adsorbed on fibre surfaces and that in the liquid phase were able to disperse the fibre suspension due to the ability of CMC to reduce fibre-to-fibre friction in both phases. Adsorbed CMC promoted the formation of a water-rich microfibrillar gel on the fibre surfaces through the spreading out of microfibrils, leading to a decrease in friction at the fibre-fibre contact points and to the increased dispersion of fibres. CMC in the liquid phase of the suspension was in turn thought to prevent fibre-to-fibre contacts due to the large physical size of the CMC molecules. CMC in both phases had detrimental effects on dewatering of the pulp suspension, but adsorbed CMC caused more plugging of the filter cake, and this was attributed to its ability to disperse fibre fines, in particular. Thus, adsorbed CMC also reduced fines retention considerably more than did CMC in the liquid phase of a suspension.

  14. Explosive Blast Neuropathology and Seizures

    Directory of Open Access Journals (Sweden)

    S. Krisztian eKovacs

    2014-04-01

    Full Text Available Traumatic brain injury (TBI due to explosive blast exposure is a leading combat casualty. It is also implicated as a key contributor to war related mental health diseases. A clinically important consequence of all types of TBI is a high risk for development of seizures and epilepsy. Seizures have been reported in patients who have suffered blast injuries in the Global War on Terror but the exact prevalence is unknown. The occurrence of seizures supports the contention that explosive blast leads to both cellular and structural brain pathology. Unfortunately, the exact mechanism by which explosions cause brain injury is unclear, which complicates development of meaningful therapies and mitigation strategies. To help improve understanding, detailed neuropathological analysis is needed. For this, histopathological techniques are extremely valuable and indispensable. In the following we will review the pathological results, including those from immunohistochemical and special staining approaches, from recent preclinical explosive blast studies.

  15. Suppression of stratified explosive interactions

    Energy Technology Data Exchange (ETDEWEB)

    Meeks, M.K.; Shamoun, B.I.; Bonazza, R.; Corradini, M.L. [Wisconsin Univ., Madison, WI (United States). Dept. of Nuclear Engineering and Engineering Physics

    1998-01-01

    Stratified Fuel-Coolant Interaction (FCI) experiments with Refrigerant-134a and water were performed in a large-scale system. Air was uniformly injected into the coolant pool to establish a pre-existing void which could suppress the explosion. Two competing effects due to the variation of the air flow rate seem to influence the intensity of the explosion in this geometrical configuration. At low flow rates, although the injected air increases the void fraction, the concurrent agitation and mixing increases the intensity of the interaction. At higher flow rates, the increase in void fraction tends to attenuate the propagated pressure wave generated by the explosion. Experimental results show a complete suppression of the vapor explosion at high rates of air injection, corresponding to an average void fraction of larger than 30%. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-14

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

  17. X-Ray photoelectron spectroscopic investigation of phenosafranine adsorbed onto micro and mesoporous materials

    Indian Academy of Sciences (India)

    S Easwaramoorthi; K Ananthanarayanan; B Sreedhar; P Natarajan

    2009-09-01

    The phenosafranine adsorbed onto the micro and mesoporous materials prepared by ion exchange method and interaction of the dye with host materials were studied by X-ray photoelectron spectroscopy to elucidate the influence of the host matrix on the binding energy of N 1s orbital. Core level N 1s X-ray photoelectron spectroscopy reveals the interaction between the dye and the solid surface through the hydrogen bonding between the hydrogen atoms of primary amino groups in dye molecule and the oxygen atom of surface hydroxyl groups. The strength of the hydrogen bonding depends on the nature of the solid surface. In the dye adsorbed onto the micro and mesoporous materials the interaction between adsorbed phenosafranine and the surfaces of the porous materials are found to modify the optical spectra and the excited state dynamics of the confined phenosafranine molecules. The change in photophysical properties of phenosafranine adsorbed on to the host materials on dehydration at elevated temperatures is attributed to the modification of host surface during dehydration process.

  18. Removal of antibiotics from water using sewage sludge- and waste oil sludge-derived adsorbents.

    Science.gov (United States)

    Ding, Rui; Zhang, Pengfei; Seredych, Mykola; Bandosz, Teresa J

    2012-09-01

    Sewage sludge- and waste oil sludge-derived materials were tested as adsorbents of pharmaceuticals from diluted water solutions. Simultaneous retention of eleven antibiotics plus two anticonvulsants was examined via batch adsorption experiments. Virgin and exhausted adsorbents were examined via thermal and FTIR analyses to elucidate adsorption mechanisms. Maximum adsorption capacities for the 6 materials tested ranged from 80 to 300 mg/g, comparable to the adsorption capacities of antibiotics on various activated carbons (200-400 mg/g) reported in the literature. The performance was linked to surface reactivity, polarity and porosity. A large volume of pores similar in size to the adsorbate molecules with hydrophobic carbon-based origin of pore walls was indicated as an important factor promoting the separation process. Moreover, the polar surface of an inorganic phase in the adsorbents attracted the functional groups of target molecules. The presence of reactive alkali metals promoted reaction with acidic groups, formation of salts and their precipitation in the pore system.

  19. Explosion modelling for complex geometries

    Science.gov (United States)

    Nehzat, Naser

    A literature review suggested that the combined effects of fuel reactivity, obstacle density, ignition strength, and confinement result in flame acceleration and subsequent pressure build-up during a vapour cloud explosion (VCE). Models for the prediction of propagating flames in hazardous areas, such as coal mines, oil platforms, storage and process chemical areas etc. fall into two classes. One class involves use of Computation Fluid Dynamics (CFD). This approach has been utilised by several researchers. The other approach relies upon a lumped parameter approach as developed by Baker (1983). The former approach is restricted by the appropriateness of sub-models and numerical stability requirements inherent in the computational solution. The latter approach raises significant questions regarding the validity of the simplification involved in representing the complexities of a propagating explosion. This study was conducted to investigate and improve the Computational Fluid Dynamic (CFD) code EXPLODE which has been developed by Green et al., (1993) for use on practical gas explosion hazard assessments. The code employs a numerical method for solving partial differential equations by using finite volume techniques. Verification exercises, involving comparison with analytical solutions for the classical shock-tube and with experimental (small-scale, medium and large-scale) results, demonstrate the accuracy of the code and the new combustion models but also identify differences between predictions and the experimental results. The project has resulted in a developed version of the code (EXPLODE2) with new combustion models for simulating gas explosions. Additional features of this program include the physical models necessary to simulate the combustion process using alternative combustion models, improvement to the numerical accuracy and robustness of the code, and special input for simulation of different gas explosions. The present code has the capability of

  20. Lidar Detection of Explosives Traces

    Directory of Open Access Journals (Sweden)

    Bobrovnikov Sergei M.

    2016-01-01

    Full Text Available The possibility of remote detection of traces of explosives using laser fragmentation/laser-induced fluorescence (LF/LIF is studied. Experimental data on the remote visualization of traces of trinitrotoluene (TNT, hexogen (RDX, trotyl-hexogen (Comp B, octogen (HMX, and tetryl with a scanning lidar detector of traces of nitrogen-containing explosives at a distance of 5 m are presented.

  1. PROPERTIES AND THERMODYNAMICS OF ADSORPTION OF BENZOIC ACID ONTO XAD-4 AND A WATER-COMPATIBLE HYPERCROSSLINKED ADSORBENT

    Institute of Scientific and Technical Information of China (English)

    Fu-qiang Liu; Jin-long Chen; Ai-min Li; Zheng-hao Fei; Zhao-lian Zhu; Quan-xing Zhang

    2003-01-01

    The adsorption behavior of benzoic acid onto a water-compatible hypercrosslinked polymeric adsorbent NJ-8 was compared with that onto macroporous Amberlite XAD-4. This paper focuses on the static equilibrium adsorption behaviors,the adsorption thermodynamics and the column dynamic adsorption profiles. Five isotherm models are used to fit the results.This shows that the Freundlich equation can give a perfect fit. The specific surface area of NJ-8 is about as high as that of Amberlite XAD-4, but the adsorbing capacity for benzoic acid on NJ-8 is about 14.9%-64.8% higher than that on Amberlite XAD-4, which is attributed to its microporous mechanism and partial polarity. The negative values of the adsorption enthalpy are indicative of an exothermic process. Both enthalpy and free energy changes of adsorption manifest a physical sorption process. The negative values of the adsorption entropy indicate that adsorption is well consistent with the restricted mobilities and the configurations of the adsorbed molecules on the surface of the studied adsorbents with superficial heterogeneity. Both adsorbents were used in mini-column experiments to demonstrate the higher breakthrough adsorbing capacity of the hypercrosslinked polymeric adsorbent NJ-8 to benzoic acid, as compared with that of Amberlite XAD-4.

  2. Simulation Analysis of Indoor Gas Explosion Damage

    Institute of Scientific and Technical Information of China (English)

    钱新明; 陈林顺; 冯长根

    2003-01-01

    The influence factors and process of indoor gas explosion are studied with AutoReaGas explosion simulator. The result shows that venting pressure has great influence on the indoor gas explosion damage. The higher the venting pressure is, the more serious the hazard consequence will be. The ignition location has also evident effect on the gas explosion damage. The explosion static overpressure would not cause major injury to person and serious damage to structure in the case of low venting pressure (lower than 2 kPa). The high temperature combustion after the explosion is the major factor to person injury in indoor gas explosion accidents.

  3. Tagging of Explosives for Detection

    Directory of Open Access Journals (Sweden)

    J. S. Gharia

    2000-01-01

    Full Text Available This paper gives the results of a study on estimation of shelf life of2,3-dimethyI2,3-dinitrobutane (DMNB-tagged RDX and PETN expiosives by monitoring DMNB depletion by high performanceliquid chromatography and simultaneously recording the detectability of the tagged explosive composition using explosive vapoUf detector Model-97 HS. DMNB was incorporated in the explosive using methanol as solvent for DMNB and the explosive compositions were stored at 35,55 and 75 °C over a long period. Methods developed for preparing the homogeneously tagged composition with DMNB at 0.5 per cent level and for the analysis ofDMNB for ensuring homogeneity of DMNB in the composition are described. The results show no change in compatibility and sensitivity on the incorporation of DMNB in the explosive. Estimation of shelf life of DMNB in the explosive was done for a period of storage of 202-304 days at different temperatures.

  4. Single- and multiphoton ionization processes in molecules

    International Nuclear Information System (INIS)

    This dissertation is theoretical in nature and can be separated into two main areas: (1) single- and multiphoton ionization studies of a novel photoelectron effect, and (2) single-photon ionization studies of simple clusters as models for adsorbate photoemission. The first area centers on the phenomenon of circular dichroism in photoelectron angular distributions (CDAD). CDAD is shown to exist from oriented linear molecules, adsorbed atoms, and aligned atoms and molecules in the gas phase. The calculations presented here are the first to demonstrate the experimental feasability of CDAD studies. CDAD is shown to be a measureable effect which exists because the photoelectron collection direction can break the symmetry of these otherwise highly symmetric systems. As a direct results of the work presented here, CDAD has now been observed experimentally. Coupled with resonantly enhanced multiphoton ionization (REMPI), CDAD is shown to be a powerful probe of unknown alignment in gas phase atomic and molecular samples. The second area of research focuses on the simple oriented molecules NiCO and NiN2 as models for the corresponding adsorbate systems. These simple models provide insight into features observed in the experimental angle-resolved photoemission spectra

  5. Scanning tunneling microscopy studies of organic monolayers adsorbed on the rhodium(111) crystal surface

    Energy Technology Data Exchange (ETDEWEB)

    Cernota, Paul D.

    1999-08-01

    Scanning Tunneling Microscopy studies were carried out on ordered overlayers on the (111) surface of rhodium. These adsorbates include carbon monoxide (CO), cyclohexane, cyclohexene, 1,4-cyclohexadiene, para-xylene, and meta-xylene. Coadsorbate systems included: CO with ethylidyne, CO with para- and meta-xylene, and para-xylene with meta-xylene. In the case of CO, the structure of the low coverage (2x2) overlayer has been observed. The symmetry of the unit cell in this layer suggests that the CO is adsorbed in the 3-fold hollow sites. There were also two higher coverage surface structures with ({radical}7x{radical}7) unit cells. One of these is composed of trimers of CO and has three CO molecules in each unit cell. The other structure has an additional CO molecule, making a total of four. This extra CO sits on a top site.

  6. Relaxation of surface stress induced by an organic adsorbate: PTCDA on vicinal Ag(111)

    Energy Technology Data Exchange (ETDEWEB)

    Pollinger, Florian; Vrdoljak, Pavo; Fertig, Dominik; Schmitt, Stefan; Kumpf, Christian; Schoell, Achim; Umbach, Eberhard [Universitaet Wuerzburg, Experimentelle Physik II, Am Hubland, 97074 Wuerzburg (Germany); Tian, Zhen; Sander, Dirk; Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany)

    2007-07-01

    Self-organization of metallic surfaces on large scales can be induced by the adsorption of organic molecules and has been observed in several experiments. One example is the growth of 3,4,9,10-perylenetetracarboxylic-acid dianhydride (PTCDA) on stepped (8.5 -vicinal) Ag(111) surfaces. At elevated temperatures, the adsorbate molecules lead to a bunching of substrate steps, which agglomerate to facets of critical sizes. The facets arrange in a coverage-dependent grating-like pattern on a mesoscopic length scale. The resulting order requires a long-range interaction which is mediated by the substrate. It can be explained by a change of surface stress induced by the adsorbate layer. Experimentally, such a change is directly accessible by an optical cantilever bending technique. We monitored the bending of a faceting thin Ag(10 8 7) crystal with this method in order to quantify the occurring relaxation of surface stress.

  7. Theoretical Insight of Physical Adsorption for a Single Component Adsorbent + Adsorbate System: II. The Henry Region

    KAUST Repository

    Chakraborty, Anutosh

    2009-07-07

    The Henry coefficients of a single component adsorbent + adsorbate system are calculated from experimentally measured adsorption isotherm data, from which the heat of adsorption at zero coverage is evaluated. The first part of the papers relates to the development of thermodynamic property surfaces for a single-component adsorbent + adsorbate system1 (Chakraborty, A.; Saha, B. B.; Ng, K. C.; Koyama, S.; Srinivasan, K. Langmuir 2009, 25, 2204). A thermodynamic framework is presented to capture the relationship between the specific surface area (Ai) and the energy factor, and the surface structural and the surface energy heterogeneity distribution factors are analyzed. Using the outlined approach, the maximum possible amount of adsorbate uptake has been evaluated and compared with experimental data. It is found that the adsorbents with higher specific surface areas tend to possess lower heat of adsorption (ΔH°) at the Henry regime. In this paper, we have established the definitive relation between Ai and ΔH° for (i) carbonaceous materials, metal organic frameworks (MOFs), carbon nanotubes, zeolites + hydrogen, and (ii) activated carbons + methane systems. The proposed theoretical framework of At and AH0 provides valuable guides for researchers in developing advanced porous adsorbents for methane and hydrogen uptake. © 2009 American Chemical Society.

  8. Effect of Adsorbent Diameter on the Performance of Adsorption Refrigeration

    Institute of Scientific and Technical Information of China (English)

    黄宏宇; 何兆红; 袁浩然; 小林敬幸; 赵丹丹; 窪田光宏; 郭华芳

    2014-01-01

    Adsorbents are important components in adsorption refrigeration. The diameter of an adsorbent can af-fect the heat and mass transfer of an adsorber. The effect of particle diameter on effective thermal conductivity was investigated. The heat transfer coefficient of the refrigerant and the void rate of the adsorbent layer can also affect the effective thermal conductivity of adsorbents. The performance of mass transfer in the adsorber is better when pressure drop decreases. Pressure drop decreases with increasing permeability. The permeability of the adsorbent layer can be improved with increasing adsorbent diameter. The effect of adsorbent diameter on refrigeration output power was experimentally studied. Output power initially increases and then decreases with increasing diameter under different cycle time conditions. Output power increases with decreasing cycle time under similar diameters.

  9. Hadron Molecules

    CERN Document Server

    Gutsche, Thomas; Faessler, Amand; Lee, Ian Woo; Lyubovitskij, Valery E

    2010-01-01

    We discuss a possible interpretation of the open charm mesons $D_{s0}^*(2317)$, $D_{s1}(2460)$ and the hidden charm mesons X(3872), Y(3940) and Y(4140) as hadron molecules. Using a phenomenological Lagrangian approach we review the strong and radiative decays of the $D_{s0}^* (2317)$ and $D_{s1}(2460)$ states. The X(3872) is assumed to consist dominantly of molecular hadronic components with an additional small admixture of a charmonium configuration. Determing the radiative ($\\gamma J/\\psi$ and $\\gamma \\psi(2s)$) and strong ($J/\\psi 2\\pi $ and $ J/\\psi 3\\pi$) decay modes we show that present experimental observation is consistent with the molecular structure assumption of the X(3872). Finally we give evidence for molecular interpretations of the Y(3940) and Y(4140) related to the observed strong decay modes $J/\\psi + \\omega$ or $J/\\psi + \\phi$, respectively.

  10. Removal of Erythrosine B dye from water effluents using crop waste pumpkin seed hulls as adsorbent

    OpenAIRE

    Apostol, Laura Carmen; Ghinea, Cristina; Alves, M. M.; Gavrilescu, Maria

    2016-01-01

    Erythrosine B is widely used for coloring in various applications, especially in the food industry, despite its already proved toxicity and carcinogenicity. The agrowaste pumpkin seed hulls were applied as potential adsorbent for the removal of Erythrosine from aqueous solutions. Adsorption mechanism and kinetics were analyzed for design purposes. The seed hulls were characterized by specific techniques before and after dye retention. It was found that the attachment of Erythrosine B molecule...

  11. The biogeochemical cycle of the adsorbed template. II - Selective adsorption of mononucleotides on adsorbed polynucleotide templates

    Science.gov (United States)

    Lazard, Daniel; Lahav, Noam; Orenberg, James B.

    1988-01-01

    Experimental results are presented for the verification of the specific interaction step of the 'adsorbed template' biogeochemical cycle, a simple model for a primitive prebiotic replication system. The experimental system consisted of gypsum as the mineral to which an oligonucleotide template attaches (Poly-C or Poly-U) and (5-prime)-AMP, (5-prime)-GMP, (5-prime)-CMP and (5-prime)-UMP as the interacting biomonomers. When Poly-C or Poly-U were used as adsorbed templates, (5-prime)-GMP and (5-prime)-AMP, respectively, were observed to be the most strongly adsorbed species.

  12. Organosilicon Ion-Exchange and Complexing Adsorbents

    Institute of Scientific and Technical Information of China (English)

    M. Voronkov; N. Vlasova; Yu. Pozhidaev; L. Belousova

    2005-01-01

    @@ 1Introduction Modification of mineral synthetic or natural substrates by organosilicon G-functionally substituted monomers, copolycondensation of the latter with organic and organosilicon compounds, and hydrolytic polycondensation of these monomers are the most widely used methods of synthesis of organosilicon adsorbents.

  13. Radon emanation from radium specific adsorbents.

    Science.gov (United States)

    Alabdula'aly, Abdulrahman I; Maghrawy, Hamed B

    2010-01-01

    Pilot studies were undertaken to quantify the total activity of radon that is eluted following no-flow periods from several Ra-226 adsorbents loaded to near exhaustion. The adsorbents studied included two types of barium sulphate impregnated alumina (ABA-8000 and F-1) and Dowex MSC-1 resin treated by either barium hydroxide or barium chloride. In parallel, radium loaded plain activated aluminas and Dowex MSC-1 resin were similarly investigated. The results revealed that radon was quantitatively eluted during the first few bed volumes of column operation after no-flow periods. Although similar radon elution profiles were obtained, the position of the radon peak was found to vary and depended on the adsorbent type. Radon levels up to 24 and 14 kBq dm(-3) were measured after a rest period of 72h from radium exhausted Dowex MSC-1 treated with barium chloride and F-1 impregnated alumina with barium sulphate, respectively. The eluted radon values measured experimentally were compared to those calculated theoretically from accumulated radium quantities for the different media. For plain adsorbents, an agreement better than 10% was obtained. For treated resin-types a consistency within 30% but for impregnated alumina-types high discrepancy between respective values were obtained.

  14. XPS and XAS investigation of condensed and adsorbed n-octane on a Cu(110) surface

    CERN Document Server

    Weiss, K; Triguero, L; Ogasawara, H; Garnier, M G; Pettersson, L G M; Nilsson, A

    2003-01-01

    The electronic structure of n-octane adsorbed on Cu(110) is studied by using X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) in combination with cluster model calculations in the framework of density functional theory (DFT). The molecule is found to be well oriented on the surface, which is seen from the high degree of XAS dichroism. Saturated hydrocarbons are commonly considered to physisorb on metals such as Cu(110), but still the C 1s XAS spectra reveal large changes in the electronic structure of the adsorbed octane relative to the free molecule. We find that the XAS resonances corresponding to the molecular Rydberg-valence states are strongly quenched upon adsorption and that there is a significant hybridization of the molecular valence orbitals with the metal bands. In addition to a precise interpretation of the XAS spectra, we present details on the molecular orbital structure of the adsorbed octane molecule. We also discuss shifts in the relative binding energies of the ...

  15. Development and Testing of Molecular Adsorber Coatings

    Science.gov (United States)

    Abraham, Nithin; Hasegawa, Mark; Straka, Sharon

    2012-01-01

    The effect of on-orbit molecular contamination has the potential to degrade the performance of spaceflight hardware and diminish the lifetime of the spacecraft. For example, sensitive surfaces, such as optical surfaces, electronics, detectors, and thermal control surfaces, are vulnerable to the damaging effects of contamination from outgassed materials. The current solution to protect these surfaces is through the use of zeolite coated ceramic adsorber pucks. However, these pucks and its additional complex mounting hardware requirements result in several disadvantages, such as size, weight, and cost related concerns, that impact the spacecraft design and the integration and test schedule. As a result, a new innovative molecular adsorber coating was developed as a sprayable alternative to mitigate the risk of on-orbit molecular contamination. In this study, the formulation for molecular adsorber coatings was optimized using various binders, pigment treatment methods, binder to pigment ratios, thicknesses, and spray application techniques. The formulations that passed coating adhesion and vacuum thermal cycling tests were further tested for its adsorptive capacity. Accelerated molecular capacitance tests were performed in an innovatively designed multi-unit system containing idealized contaminant sources. This novel system significantly increased the productivity of the testing phase for the various formulations that were developed. Work performed during the development and testing phases has demonstrated successful application of molecular adsorber coatings onto metallic substrates, as well as, very promising results for the adhesion performance and the molecular capacitance of the coating. Continued testing will assist in the qualification of molecular adsorber coatings for use on future contamination sensitive spaceflight missions.

  16. Constructing a proton titration curve from ion-step measurements, applied to a membrane with adsorbed protein

    NARCIS (Netherlands)

    Eijkel, Jan C.T.; Bosch, Coen; Olthuis, Wouter; Bergveld, Piet

    1997-01-01

    A new measuring method is described for obtaining a proton titration curve. The curve is obtained from a microporous composite membrane, consisting of polystyrene beads in an agarose matrix, with lysozyme molecules adsorbed to the bead surface. The membrane is incorporated into a sensor system by de

  17. Observation of the dynamical change in a water monolayer adsorbed on a ZnO surface.

    Science.gov (United States)

    Dulub, Olga; Meyer, Bernd; Diebold, Ulrike

    2005-09-23

    A combined scanning tunneling microscopy and density-functional theory (DFT) study shows a rich structure of water monolayers adsorbed on ZnO(1010) at room temperature. Most of the water is in a lowest-energy configuration where every second molecule is dissociated. It coexists with an energetically almost degenerate configuration consisting of a fully molecular water monolayer. Parts of the layer continuously switch back and forth between these two states. DFT calculations reveal that water molecules repeatedly associate and dissociate in this sustained dynamical process. PMID:16197151

  18. THE INFLUENCE OF BARRIERS ON FLAME AND EXPLOSION WAVE IN GAS EXPLOSION

    Institute of Scientific and Technical Information of China (English)

    林柏泉; 周世宁; 张仁贵

    1998-01-01

    This paper researches into the influence of barriers on flame and explosion wave in gasexplosion on the basis of experiment. The result shows that the barrier is very important to thetransmission of flame and explosion wave in gas explosion. When there are barriers, the speed oftransmission would be very fast and shock wave will appear in gas explosion, which would in-crease gas explosion power. The result of research is very important to prevent gas explosion anddecrease the power of it.

  19. Explosion limits for combustible gases

    Institute of Scientific and Technical Information of China (English)

    TONG Min-ming; WU Guo-qing; HAO Ji-fei; DAI Xin-lian

    2009-01-01

    Combustible gases in coal mines are composed of methane, hydrogen, some multi-carbon alkane gases and other gases. Based on a numerical calculation, the explosion limits of combustible gases were studied, showing that these limits are related to the concentrations of different components in the mixture. With an increase of C4H10 and C6H14, the Lower ExplosionLimit (LEL) and Upper Explosion-Limit (UEL) of a combustible gas mixture will decrease clearly. For every 0.1% increase in C4H10 and C6H14, the LEL decreases by about 0.19% and the UEL by about 0.3%. The results also prove that, by increasing the amount of H2, the UEL of a combustible gas mixture will increase considerably. If the level of H2 increases by 0.1%, the UEL will increase by about 0.3%. However, H2 has only a small effect on the LEL of the combustible gas mixture. Our study provides a theoretical foundation for judging the explosion risk of an explosive gas mixture in mines.

  20. Molecules and Clusters in Intense Laser Fields

    Science.gov (United States)

    Posthumus, Jan

    2009-09-01

    Preface; 1. Ultra-high intensity based on Ti:Sapphire Philip F. Taday and Andrew J. Langley; 2. Diatomic molecules in intense laser fields Jan H. Posthumus and James F. McCann; 3. Small polyatomic molecules in intense laser fields C. Cornaggia; 4. Coherent control in intense laser fields Eric Charron and Brian Sheehy; 5. Experimental studies of laser-heated rare gas clusters M. Lezius and M. Schmidt; 6. Single cluster explosions and high harmonic generation John W. G. Tisch and Emma Springate; 7. Intense laser interaction with extended cluster media Roland A. Smith and Todd Ditmire.

  1. The Quiet Explosion

    Science.gov (United States)

    2008-07-01

    A European-led team of astronomers are providing hints that a recent supernova may not be as normal as initially thought. Instead, the star that exploded is now understood to have collapsed into a black hole, producing a weak jet, typical of much more violent events, the so-called gamma-ray bursts. The object, SN 2008D, is thus probably among the weakest explosions that produce very fast moving jets. This discovery represents a crucial milestone in the understanding of the most violent phenomena observed in the Universe. Black Hole ESO PR Photo 23a/08 A Galaxy and two Supernovae These striking results, partly based on observations with ESO's Very Large Telescope, will appear tomorrow in Science Express, the online version of Science. Stars that were at birth more massive than about 8 times the mass of our Sun end their relatively short life in a cosmic, cataclysmic firework lighting up the Universe. The outcome is the formation of the densest objects that exist, neutron stars and black holes. When exploding, some of the most massive stars emit a short cry of agony, in the form of a burst of very energetic light, X- or gamma-rays. In the early afternoon (in Europe) of 9 January 2008, the NASA/STFC/ASI Swift telescope discovered serendipitously a 5-minute long burst of X-rays coming from within the spiral galaxy NGC 2770, located 90 million light-years away towards the Lynx constellation. The Swift satellite was studying a supernova that had exploded the previous year in the same galaxy, but the burst of X-rays came from another location, and was soon shown to arise from a different supernova, named SN 2008D. Researchers at the Italian National Institute for Astrophysics (INAF), the Max-Planck Institute for Astrophysics (MPA), ESO, and at various other institutions have observed the supernova at great length. The team is led by Paolo Mazzali of INAF's Padova Observatory and MPA. "What made this event very interesting," says Mazzali, "is that the X-ray signal was very

  2. Coulomb explosion of "hot spot"

    CERN Document Server

    Oreshkin, V I; Chaikovsky, S A; Artyomov, A P

    2016-01-01

    The study presented in this paper has shown that the generation of hard x rays and high-energy ions, which are detected in pinch implosion experiments, may be associated with the Coulomb explosion of the hot spot that is formed due to the outflow of the material from the pinch cross point. During the process of material outflow, the temperature of the hot spot plasma increases, and conditions arise for the plasma electrons to become continuously accelerated. The runaway of electrons from the hot spot region results in the buildup of positive space charge in this region followed by a Coulomb explosion. The conditions for the hot spot plasma electrons to become continuously accelerated have been revealed and estimates have been obtained for the kinetic energy of the ions generated by the Coulomb explosion.

  3. Seismic coupling of nuclear explosions

    International Nuclear Information System (INIS)

    The new Giant Magnet Experimental Facility employing digital recording of explosion induced motion has been constructed and successfully tested. Particle velocity and piezoresistance gage responses can be measured simultaneously thus providing the capability for determining the multi-component stress-strain history in the test material. This capability provides the information necessary for validation of computer models used in simulation of nuclear underground testing, chemical explosion testing, dynamic structural response, earth penetration response, and etc. This report discusses fully coupled and cavity decoupled explosions of the same energy (0.622 kJ) were carried out as experiments to study wave propagation and attenuation in polymethylmethacrylate (PMMA). These experiments produced particle velocity time histories at strains from 2 x 10-3 to as low as 5.8 x 10-6. Other experiments in PMMA, reported recently by Stout and Larson8 provide additional particle velocity data to strains of 10-1

  4. Evidence for Nearby Supernova Explosions

    CERN Document Server

    Benítez, N; Canelles, M; Benitez, Narciso; Maiz-Apellaniz, Jesus; Canelles, Matilde

    2002-01-01

    Supernova explosions are one of the most energetic--and potentially lethal--phenomena in the Universe. Scientists have speculated for decades about the possible consequences for life on Earth of a nearby supernova, but plausible candidates for such an event were lacking. Here we show that the Scorpius-Centaurus OB association, a group of young stars currently located at~130 parsecs from the Sun, has generated 20 SN explosions during the last 11 Myr, some of them probably as close as 40 pc to our planet. We find that the deposition on Earth of 60Fe atoms produced by these explosions can explain the recent measurements of an excess of this isotope in deep ocean crust samples. We propose that ~2 Myr ago, one of the SNe exploded close enough to Earth to seriously damage the ozone layer, provoking or contributing to the Pliocene-Pleistocene boundary marine extinction.

  5. Optimal dynamic detection of explosives

    Energy Technology Data Exchange (ETDEWEB)

    Moore, David Steven [Los Alamos National Laboratory; Mcgrane, Shawn D [Los Alamos National Laboratory; Greenfield, Margo T [Los Alamos National Laboratory; Scharff, R J [Los Alamos National Laboratory; Rabitz, Herschel A [PRINCETON UNIV; Roslund, J [PRINCETON UNIV

    2009-01-01

    The detection of explosives is a notoriously difficult problem, especially at stand-off distances, due to their (generally) low vapor pressure, environmental and matrix interferences, and packaging. We are exploring optimal dynamic detection to exploit the best capabilities of recent advances in laser technology and recent discoveries in optimal shaping of laser pulses for control of molecular processes to significantly enhance the standoff detection of explosives. The core of the ODD-Ex technique is the introduction of optimally shaped laser pulses to simultaneously enhance sensitivity of explosives signatures while reducing the influence of noise and the signals from background interferents in the field (increase selectivity). These goals are being addressed by operating in an optimal nonlinear fashion, typically with a single shaped laser pulse inherently containing within it coherently locked control and probe sub-pulses. With sufficient bandwidth, the technique is capable of intrinsically providing orthogonal broad spectral information for data fusion, all from a single optimal pulse.

  6. Investigation on Adsorption State of Surface Adsorbate on Silicon Wafer

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    An adsorption kinetics model for adsorbate on the specularly polished silicon wafer was suggested. The mathematical model of preferential adsorption and the mechanism controlling the adsorption state of adsorbate were discussed.

  7. Effects of molecule anchoring and dispersion on nanoscopic friction under electrochemical control

    International Nuclear Information System (INIS)

    The application of electric fields is a promising strategy for in situ control of friction. While there have recently been many experimental studies on friction under the influence of electric fields, theoretical understanding is very limited. Recently, we introduced a simple theoretical model for friction under electrochemical conditions that focused on the interaction of a force microscope tip with adsorbed molecules whose orientation was dependent on the applied electric field. Here we focus on the effects of anchoring of the molecules on friction. We show that anchoring affects the intensity and width of the peak in the friction that occurs near a reorientation transition of adsorbed molecules, and explain this by comparing the strength of molecule–molecule and molecule–tip interactions. We derive a dispersion relation for phonons in the layer of adsorbed molecules and demonstrate that it can be used to understand important features of the frictional response. (paper)

  8. Physisorption versus chemisorption of oxygen molecules on Ag(100)

    Science.gov (United States)

    Mehlhorn, Michael; Morgenstern, Karina

    2016-04-01

    We compare the adsorption of oxygen molecules on Ag(100) at 60 K and at 100 K. At both temperatures, the molecules form islands. Differences between the species adsorbed at the two temperatures in both low-temperature scanning tunneling microscopy and inelastic electron tunneling spectroscopy are attributed to two different adsorption states, a chemisorbed state after 100 K adsorption and a physisorbed state after 60 K adsorption.

  9. Oxidation of monovacancies in graphene by oxygen molecules

    KAUST Repository

    Kaloni, Thaneshwor P.

    2011-10-14

    We study the oxidation of monovacancies in graphene by oxygen molecules using first principles calculations. In particular, we address the local magnetic moments which develop at monovacancies and show that they remain intact when a molecule is adsorbed such that the dangling carbon bonds are not fully saturated. However, the lowest energy configuration does not maintain dangling bonds and is found to be semiconducting. Our data can explain the experimentally observed behavior of graphene under exposure to an oxygen plasma.

  10. Removal of micropollutants from water by nanocomposite membrane adsorbers

    OpenAIRE

    Niedergall, K.; Bach, M.; Hirth, T.; Tovar, G.E.M.; Schiestel, T.

    2014-01-01

    Nanoscaled spheric polymer adsorbers with a variety of chemical surface functionalities were synthesized by miniemulsion polymerization and inverse miniemulsion polymerization. The nanospheres were embedded in polyethersulfone (PES) matrices by a wet-phase inversion process to form nanocomposite membrane adsorbers. The resulting membrane adsorbers were characterized by scanning electron microscopy (SEM), pore size measurements, water flux measurements and various adsorption experiments. The m...

  11. Fluorescence of dyes adsorbed on highly organized nanostructured gold surfaces

    NARCIS (Netherlands)

    Levi, Stefano A.; Mourran, Ahmed; Spatz, Joachim P.; Veggel, van Frank C.J.M.; Reinhoudt, David N.; Möller, M.

    2002-01-01

    It is shown that fluorescent dyes can be adsorbed selectively on gold nanoparticles which are immobilized on a glass substrate and that the fluorescence originating from the adsorbed dyes exhibits significantly less quenching when compared to dyes adsorbed on bulk gold. Self-assembled monolayers of

  12. Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mayes, Richard T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Janke, Christopher James [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dai, Sheng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Das, S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liao, W. -P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wood, Jordana [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gill, Gary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Byers, Maggie Flicker [Univ. of Texas, Austin, TX (United States); Schneider, Eric [Univ. of Texas, Austin, TX (United States)

    2015-09-30

    The Fuel Resources program of the Fuel Cycle Research and Development program of the Office of Nuclear Energy (NE) is focused on identifying and implementing actions to assure that nuclear fuel resources are available in the United States. An immense source of uranium is seawater, which contains an estimated amount of 4.5 billion tonnes of dissolved uranium. This unconventional resource can provide a price cap and ensure centuries of uranium supply for future nuclear energy production. NE initiated a multidisciplinary program with participants from national laboratories, universities, and research institutes to enable technical breakthroughs related to uranium recovery from seawater. The goal is to develop advanced adsorbents to reduce the seawater uranium recovery technology cost and uncertainties. Under this program, Oak Ridge National Laboratory (ORNL) has developed a new amidoxime-based adsorbent of high surface area, which tripled the uranium capacity of leading Japanese adsorbents. Parallel efforts have been focused on the optimization of the physicochemical and operating parameters used during the preparation of the adsorbent for deployment. A set of parameters that need to be optimized are related to the conditioning of the adsorbent with alkali solution, which is necessary prior to adsorbent deployment. Previous work indicated that alkali-conditioning parameters significantly affect the adsorbent performance. Initiated in 2014, this study had as a goal to determine optimal parameters such as base type and concentration, temperature, and duration of conditioning that maximize the uranium adsorption performance of amidoxime functionalized adsorbent, while keeping the cost of uranium production low. After base-treatment at various conditions, samples of adsorbent developed at ORNL were tested in this study with batch simulated seawater solution of 8-ppm uranium concentration, batch seawater spiked with uranium nitrate at 75-100 ppb uranium, and continuous

  13. Adsorption materials for the recovery and separation of biobased molecules

    NARCIS (Netherlands)

    IJzer, Anne Corine

    2016-01-01

    In this thesis we studied several strategies to improve adsorption technology for the adsorption of biobased molecules. These strategies are based on the adsorbent as well as the adsorption process. A systematic investigation of the chemical and physical structure of resin materials and their relati

  14. Behavior of macromolecules in adsorbed layers

    Institute of Scientific and Technical Information of China (English)

    牟伯中[1; 姚恒申[2; 罗平亚[3

    2000-01-01

    A model for describing the behavior ot macromoiecuies in aosoroea layers is developed by introducing a concept of distribution density of layer thickness U based on stochastic process and probabilistic statistics. The molecular behavior of layers adsorbed on clay particle surfaces is discussed; the random distribution and its statistics of the layer thickness are given by incorporating experimental results with an ionic polyelectrolyte with the molecular weight of 1.08×106and chain charged density of 0.254.

  15. Green Adsorbents for Wastewaters: A Critical Review

    Directory of Open Access Journals (Sweden)

    George Z. Kyzas

    2014-01-01

    Full Text Available One of the most serious environmental problems is the existence of hazardous and toxic pollutants in industrial wastewaters. The major hindrance is the simultaneous existence of many/different types of pollutants as (i dyes; (ii heavy metals; (iii phenols; (iv pesticides and (v pharmaceuticals. Adsorption is considered to be one of the most promising techniques for wastewater treatment over the last decades. The economic crisis of the 2000s led researchers to turn their interest in adsorbent materials with lower cost. In this review article, a new term will be introduced, which is called “green adsorption”. Under this term, it is meant the low-cost materials originated from: (i agricultural sources and by-products (fruits, vegetables, foods; (ii agricultural residues and wastes; (iii low-cost sources from which most complex adsorbents will be produced (i.e., activated carbons after pyrolysis of agricultural sources. These “green adsorbents” are expected to be inferior (regarding their adsorption capacity to the super-adsorbents of previous literature (complex materials as modified chitosans, activated carbons, structurally-complex inorganic composite materials etc., but their cost-potential makes them competitive. This review is a critical approach to green adsorption, discussing many different (maybe in some occasions doubtful topics such as: (i adsorption capacity; (ii kinetic modeling (given the ultimate target to scale up the batch experimental data to fixed-bed column calculations for designing/optimizing commercial processes and (iii critical techno-economical data of green adsorption processes in order to scale-up experiments (from lab to industry with economic analysis and perspectives of the use of green adsorbents.

  16. Effective Thermal Conductivity of Adsorbent Packed Beds

    Science.gov (United States)

    Mori, Hideo; Hamamoto, Yoshinori; Yoshida, Suguru

    The effective thermal conductivity of adsorbent packed beds of granular zeolite 13X and granular silica gel A in the presence of stagnant steam or air was measured under different conditions of the adsorbent bed temperature, particle size and filler-gas pressure. The measured effective thermal conductivity showed to become smaller with decreasing particle size or decreasing pressure, but it was nearly independent of the bed temperature. When steam was the filler-gas, the rise in the thermal conductivity of the adsorbent particles due to steam adsorption led to the increase in the effective thermal conductivity of the bed, and this effect was not negligible at high steam pressure for the bed of large particle size. It was found that both the predictions of the effective thermal conductivity by the Hayashi et al.'s model and the Bauer-Schlünder model generally agreed well with the measurements, by considering the particle thermal conductivity rise due to steam adsorption. The thermal conductivity of a consolidated bed of granular zeolite 13X was also measured, and it was found to be much larger than that of the packed bed especially at lower pressure. The above prediction models underestimated the effective thermal conductivity of the consolidated bed.

  17. ADSORPTION OF BENZOIC ACID AND P-NITROBENZOIC ACID ON A NEW HYPERCROSSLINKED PHENOL GROUP PST ADSORBENT

    Institute of Scientific and Technical Information of China (English)

    ZHANG Gencheng; LIUFuqiang; FEI Zhenghao; LI Aimin; ZHANG Quanxing

    2003-01-01

    A comparison of the adsorption of benzoic acid and p-nitrobenzoic acid on the new hypercrosslinked polymeric adsorbent AM-I, with that by macroporous Amberlite XAD-4, including the equilibrium adsorption isotherms, the dynamic adsorption behaviors through column and the adsorption thermodynamics were studied. Results show that Freundlich equation gives a fitting adsorption isotherm. The specific surface of AM-l is only 67% of that of Amberlite XAD-4, but the adsorption capacities on AM-1 are much higher about 125%~166% than that on Amberlite XAD-4,which is contributed to the micropore mechanism and polarity. The negative values of the adsorption enthalpy are indicative of an exothermic process. Enthalpy and free energy changes of adsorption both manifest a physic-sorption process. The negative values of the adsorption entropy indicate that the adsorption is well consistent with the restricted mobilities and the configurations of the adsorbed benzoic acid molecules on the surface of studied adsorbents with superficial heterogeneity. Both adsorbents were used in mini-column experiments for adsorbing benzoic acid expecting to elucidate the higher breakthrough adsorption capacity of the new hypercrosslinked polymeric adsorbent AM-1 as compared with that of Amberlite XAD-4.

  18. Optimization of the elaboration conditions of an adsorber for the hydrogen storage; Optimisation des conditions d'elaboration d'un adsorbant pour le stockage d'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Fierro, V.; Mareche, J.F.; Furdin, G. [Nancy-1 Univ. Henri Poincare, UMR - CNRS 7555, Laboratoire de Chimie du Solide Mineral, 54 - Vandoeuvre-les-Nancy (France); Szczurek, A.; Albiniak, A. [Wroclaw Univ. of Technology, Laboratory for Lignites and Carbon Adsorbents, Institute of Chemistry and Technology of Petroleum and Coal (Poland); Latroche, M. [Chimie Metallurgique des Terres Rares, ICMPE, UMR 7182, CNRS, 94 - Thiais (France); Celzard, A. [Nancy-Univ., ENSTIB, Laboratoire de Chimie du Solide Mineral, UMR CNRS 7555, 88 - Epinal (France)

    2008-07-01

    The microporous carbon are very efficient adsorbents for the hydrogen storage, because of pores size under 2 nm. This study describes the optimization of the elaboration conditions for a carbon adsorbent for the hydrogen storage by adsorption. The storage capacity has been measured at 25 C for 20 MPa and also at 77 K for pressures between 6 and 9 MPa. the porous texture characterization has been realized by four molecule probes of increasing diameter: CO{sub 2}, N{sub 2}, C{sub 6}H{sub 6} and CCl{sub 4}. (A.L.B.)

  19. Nitrogen-rich porous adsorbents for CO2 capture and storage.

    Science.gov (United States)

    Li, Pei-Zhou; Zhao, Yanli

    2013-08-01

    The construction of physical or chemical adsorbents for CO2 capture and sequestration (CCS) is a vital technology in the interim period on the way towards a sustainable low-carbon future. The search for efficient materials to satisfy the increasing demand for CCS has become extremely important. Porous materials, including porous silica, porous carbons, and newly developed metal-organic frameworks and porous organic polymers, possessing regular and well-defined porous geometry and having a high surface area and pore volume, have been widely studied for separations on laboratory scale. On account of the dipole-quadrupole interactions between the polarizable CO2 molecule and the accessible nitrogen site, the investigations have indicated that the incorporation of accessible nitrogen-donor groups into the pore walls of porous materials can improve the affinity to CO2 and increase the CO2 uptake capacity and selectivity. The CO2 -adsorption process based on solid nitrogen-rich porous adsorbents does generally not require heating of a large amount of water (60-70 wt%) for regeneration, while such a heating approach cannot be avoided in the regeneration of amine-based solution absorption processes. Thus, nitrogen-rich porous adsorbents show good regeneration properties without sacrificing high separation efficiency. As such, nitrogen-rich porous materials as highly promising CO2 adsorbents have been broadly fabricated and intensively investigated. This Focus Review highlights recent significant advances in nitrogen-rich porous materials for CCS. PMID:23744799

  20. Adsorption of prototypical amino acids on silica: Influence of the pre-adsorbed water multilayer

    Science.gov (United States)

    Remesal, Elena R.; Amaya, Javier; Graciani, Jesús; Márquez, Antonio M.; Sanz, Javier Fdez.

    2016-04-01

    We explore the interaction between acetic acid, some typical α-amino acids (α-AAs), and a fully hydroxylated (0001) surface of α-quartz by means of theoretical calculations based on the density functional theory (DFT) under periodic boundary conditions. The influence of microsolvation, represented by a water multilayer, and dispersion forces is analyzed. All the considered molecules strongly adsorb on the hydroxylated surface and prefer to adsorb molecularly. The inclusion of dispersion forces increases the interaction energies by 15-30 kJ/mol, without significant changes in structure and mode of adsorption except for histidine where the interaction is improved through protonation of the α-amine group. When the water multilayer is included a decrease in the surface-adsorbate interaction energies is observed. Also, some α-AAs, glycine and alanine, change their adsorption mode and, now, the more stable structure is the zwitterion. Adsorption as zwitterions is always favored with respect to molecular interaction when dispersion forces are taken into account. Comparing the energies of adsorbed and solvated α-AA zwitterions, it turns out that inclusion of dispersion forces predicts that solvated zwitterions are the lower energy configurations.

  1. Lead-free primary explosives

    Science.gov (United States)

    Huynh, My Hang V.

    2010-06-22

    Lead-free primary explosives of the formula (cat).sub.Y[M.sup.II(T).sub.X(H.sub.2O).sub.6-X].sub.Z, where T is 5-nitrotetrazolate, and syntheses thereof are described. Substantially stoichiometric equivalents of the reactants lead to high yields of pure compositions thereby avoiding dangerous purification steps.

  2. Explosion mitigation by water mist

    NARCIS (Netherlands)

    Wal, R. van der; Cargill, S.; Longbottom, A.; Rhijnsburger, M.P.M.; Erkel, A.G. van

    2010-01-01

    The internal explosion of an anti-ship missile or stored ammunition is a potentially catastrophic threat for a navy vessel. These events generally cause heavy blast loading and fragments to perforate the ship structure. As a solution to reduce the blast loading, the compartment can be filled with wa

  3. Turbulent Combustion in SDF Explosions

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, A L; Bell, J B; Beckner, V E

    2009-11-12

    A heterogeneous continuum model is proposed to describe the dispersion and combustion of an aluminum particle cloud in an explosion. It combines the gas-dynamic conservation laws for the gas phase with a continuum model for the dispersed phase, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by phenomenological models. It incorporates a combustion model based on the mass conservation laws for fuel, air and products; source/sink terms are treated in the fast-chemistry limit appropriate for such gasdynamic fields, along with a model for mass transfer from the particle phase to the gas. The model takes into account both the afterburning of the detonation products of the C-4 booster with air, and the combustion of the Al particles with air. The model equations were integrated by high-order Godunov schemes for both the gas and particle phases. Numerical simulations of the explosion fields from 1.5-g Shock-Dispersed-Fuel (SDF) charge in a 6.6 liter calorimeter were used to validate the combustion model. Then the model was applied to 10-kg Al-SDF explosions in a an unconfined height-of-burst explosion. Computed pressure histories are compared with measured waveforms. Differences are caused by physical-chemical kinetic effects of particle combustion which induce ignition delays in the initial reactive blast wave and quenching of reactions at late times. Current simulations give initial insights into such modeling issues.

  4. Explosive micro-bubble actuator

    NARCIS (Netherlands)

    Broek, van den D.M.; Elwenspoek, M.

    2008-01-01

    Explosive evaporation occurs when a liquid is exposed to extremely high heat-fluxes. Within a few microseconds a bubble in the form vapour film is generated, followed by rapid growth due to the pressure impulse and finally the bubbles collapse. This effect, which already has proven its use in curren

  5. Explosive micro-bubble actuator

    NARCIS (Netherlands)

    Broek, van den D.M.; Elwenspoek, M.C.

    2007-01-01

    Explosive evaporation occurs when a thin layer of liquid reaches a very high temperature in a very short time. At these temperatures homogeneous nucleation takes place. The nucleated bubbles almost instantly coalesce forming a vapour film followed by rapid growth due to the pressure impulse and fina

  6. Statistical estimation of loads from gas explosions

    OpenAIRE

    Høiset, Stian

    1998-01-01

    In the design of structures in the offshore and process industries, the possibility of a gas explosion must always be considered. This is usually incorporated by performing explosion simulations. However, estimations based on such calculations introduce uncertainties in the design process. The main uncertainties in explosion simulations are the assumption of the gas cloud,the location of the ignition point and the properties of the explosion simulator itself. In this thesis, we try to investi...

  7. 30 CFR 77.1301 - Explosives; magazines.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Explosives; magazines. 77.1301 Section 77.1301... and Blasting § 77.1301 Explosives; magazines. (a) Detonators and explosives other than blasting agents shall be stored in magazines. (b) Detonators shall not be stored in the same magazine with...

  8. 77 FR 55108 - Explosive Siting Requirements

    Science.gov (United States)

    2012-09-07

    ... where solid propellants, energetic liquids, or other explosives are located to prepare launch vehicles... locations and facilities at a launch site where solid propellants, liquid propellants or other explosives... a launch site where solid propellants, energetic liquids, or other explosives are stored or...

  9. 14 CFR 420.63 - Explosive siting.

    Science.gov (United States)

    2010-01-01

    ... launch site boundary; (2) A listing of the maximum quantities of liquid and solid propellants and other explosives to be located at each explosive hazard facility, including the class and division for each solid explosive and the hazard and compatibility group for each liquid propellant; and (3) A description of...

  10. Adsorbing H₂S onto a single graphene sheet: A possible gas sensor

    Energy Technology Data Exchange (ETDEWEB)

    Reshak, A. H., E-mail: maalidph@yahoo.co.uk [New Technologies-Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic); Center of Excellence Geopolymer and Green Technology, School of Material Engineering, University Malaysia Perlis, 01007 Kangar, Perlis (Malaysia); Auluck, S. [Council of Scientific and Industrial Research-National Physical Laboratory, Dr. K S Krishnan Marg, New Delhi 110012 (India)

    2014-09-14

    The electronic structure of pristine graphene sheet and the resulting structure of adsorbing a single molecule of H₂S on pristine graphene in three different sites (bridge, top, and hollow) are studied using the full potential linearized augmented plane wave method. Our calculations show that the adsorption of H₂S molecule on the bridge site opens up a small direct energy gap of about 0.1 eV at symmetry point M, while adsorption of H₂S on top site opens a gap of 0.3 eV around the symmetry point K. We find that adsorbed H₂S onto the hollow site of pristine graphene sheet causes to push the conduction band minimum and the valence band maximum towards Fermi level resulting in a metallic behavior. Comparing the angular momentum decomposition of the atoms projected electronic density of states of pristine graphene sheet with that of H₂S–graphene for three different cases, we find a significant influence of the location of the H₂S molecule on the electronic properties especially the strong hybridization between H₂S molecule and graphene sheet.

  11. Alkali-induced nanopatterning of Ag(110) surface mediated by molecular adsorbate

    Energy Technology Data Exchange (ETDEWEB)

    Mercurio, Giuseppe; Willenbockel, Martin; Weiss, Christian; Temirov, Ruslan; Subach, Sergey; Tautz, Stefan [Peter Gruenberg Institut (PGI-3), Forschungszentrum Juelich, 52425 Juelich (Germany); JARA-Fundamentals of Future Information Technology (Germany); Bauer, Oliver; Fiedler, Benjamin; Sokolowski, Moritz [Institute for Physical and Theoretical Chemistry, University of Bonn (Germany)

    2011-07-01

    It is known for decades that alkali metals initiate the restructuring of fcc metal surfaces resulting in a composite patterned morphology. On the other hand, co-adsorbed metal atoms and organic molecules often form extended 2D networks due to the metal-molecular coordination reaction. Here we report on a new type of structural modification of the molecule-substrate interface, which is not only restricted to self-assembly of the adsorbed metal atoms and molecules, but it also involves significant morphological reorganization of the metallic surface. In the experiments, potassium atoms are deposited on a monolayer of the long-range ordered PTCDA/Ag(110) phase. Subsequent annealing forces potassium atoms to intercalate under the molecular layer partially unbinding PTCDA from the substrate. The complex interaction between potassium, PTCDA and substrate induces a significant silver mass-transfer and leads to the appearance of 1D stripe-structures of K atoms and PTCDA molecules on a nanopatterned silver surface. Structural and electronic properties of this pattern were studied by means of NIXSW, XPS, LEED and LT-STM.

  12. Deconvoluting nonaxial recoil in Coulomb explosion measurements of molecular axis alignment

    Science.gov (United States)

    Christensen, Lauge; Christiansen, Lars; Shepperson, Benjamin; Stapelfeldt, Henrik

    2016-08-01

    We report a quantitative study of the effect of nonaxial recoil during Coulomb explosion of laser-aligned molecules and introduce a method to remove the blurring caused by nonaxial recoil in the fragment-ion angular distributions. Simulations show that nonaxial recoil affects correlations between the emission directions of fragment ions differently from the effect caused by imperfect molecular alignment. The method, based on analysis of the correlation between the emission directions of the fragment ions from Coulomb explosion, is used to deconvolute the effect of nonaxial recoil from experimental fragment angular distributions. The deconvolution method is then applied to a number of experimental data sets to correct the degree of alignment for nonaxial recoil, to select optimal Coulomb explosion channels for probing molecular alignment, and to estimate the highest degree of alignment that can be observed from selected Coulomb explosion channels.

  13. Atmospheric sampling glow discharge ionizataion and triple quadrupole tandem mass spectrometry for explosives vapor detection

    Energy Technology Data Exchange (ETDEWEB)

    McLuckey, S.A.; Goeringer, D.E.; Asano, K.G.; Hart, K.J.; Glish, G.L.; Grant, B.C.; Chambers, D.M.

    1993-08-01

    The detection and identification of trace vapors of hidden high explosives is an excellent example of a targeted analysis problem. It is desirable to push to ever lower levels the quantity or concentration of explosives material that provides an analytical signal, while at the same time discriminating against all other uninteresting material. The detection system must therefore combine high sensitivity with high specificity. This report describes the philosophy behind the use of atmospheric sampling glow discharge ionization, which is a sensitive, rugged, and convenient means for forming anions from explosives molecules, with tandem mass spectrometry, which provides unparalleled specificity in the identification of explosives-related ions. Forms of tandem mass spectrometry are compared and contrasted to provide a summary of the characteristics to be expected from an explosives detector employing mass spectrometry/mass spectrometry. The instrument developed for the FAA, an atmospheric sampling glow discharge/triple quadrupole mass spectrometer, is described in detail with particular emphasis on the ion source/spectrometer interface and on the capabilities of the spectrometer. Performance characteristics of the system are also described as they pertain to explosives of interest including a description of an automated procedure for the detection and identification of specific explosives. A comparison of various tandem mass spectrometers mated with atmospheric sampling glow discharge is then described and preliminary studies with a vapor preconcentration system provided by the FAA will be described.

  14. Numerical computation algorithm of explosion equations and thermodynamics parameters of mine explosives

    Institute of Scientific and Technical Information of China (English)

    李守巨; 刘迎曦; 何翔; 周圆π

    2001-01-01

    A new numerical algorithm is presented to simulate the explosion reaction process of mine explosives based on the equation of state, the equation of mass conservation and thermodynamics balance equation of explosion products. With the affection of reversible reaction of explosion products to explosion reaction equations and thermodynamics parameters considered, the computer program has been developed. The computation values show that computer simulation results are identical with the testinq ones.

  15. Numerical computation algorithm of explosion equations and thermodynamics parameters of mine explosives

    Institute of Scientific and Technical Information of China (English)

    LI Shou-ju; LIU Ying-xi; HE Xiang; ZHOU Y uan-pai

    2001-01-01

    A new numerical algorithm is presented to simulate the explosion reacti on process of mine explosives based on the equation of state, the equation of ma ss conservation and thermodynamics balance equation of explosion products. With the affection of reversible reaction of explosion products to explosion reaction equations and thermodynamics parameters considered, the computer program has be en developed. The computation values show that computer simulation results are i dentical with the testing ones.

  16. NOx Removal and Effect of Adsorbate-Adsorbate Interactions

    DEFF Research Database (Denmark)

    Khan, Tuhin Suvra

    low-index metal surfaces. Furthermore, I have used DFT calculated adsorption and transition state energies coupled with a microkinetic model to study two industrially important catalytic reactions, NH3 oxidation and selective catalytic reduction of NOx, to obtain the catalytic trends and understand...... these challenges systematically and have developed some new methods and models to counter those challenges and obtain some general understanding of the catalytic process. I have developed an adsorbate-adsorbate interaction model to include the coverage dependency of the adsorption energy in kinetic models...

  17. Damage Effects of Shelled Explosive Explosion in Concrete

    Directory of Open Access Journals (Sweden)

    Liu Yan

    2010-10-01

    Full Text Available The damage of concrete subjected to explosion loading is an important issue in defense engineering. The damage degree of concrete is related to many factors, such as the type of explosive charge, the depth of burial and the parameters of concrete. In this paper, three factors are considered for experiments of shelled explosives in concrete targets, which are the filling coefficient, length-to-diameter ratio and the depth of burial. The filling coefficient is from 0.1 to 1 by changing thickness of shell, and length-to-diameter ratio is from 2.5 to 10. The unconfined compressive strength of concrete target for test is 35MPa. The experimental results showed that the sizes of craters of concretes are varied as the filling coefficient, length-to-diameter ratio and the depth of burial. The optimal values of filling coefficient, length-to-diameter ratio and the depth of burial of shelled charges were obtained to get largest damage regions of concrete targets. This work provides a base for evaluating the damage of concrete and designing the penetrating warhead.Defence Science Journal, 2010, 60(6, pp.672-677, DOI:http://dx.doi.org/10.14429/dsj.60.434

  18. Adsorption equilibria and kinetics for phenol and cresol onto polymeric adsorbents: Effects of adsorbents/adsorbates structure and interface

    International Nuclear Information System (INIS)

    Phenol and cresol (o-, m-, and p-) were selected as the adsorbates with different dipole moment (cresol > phenol, methyl being electron-drawing group) and solubility (phenol > cresol, methyl being hydrophobic group). Macropore polymers (NDA-1800 and XAD-4), hypercrosslinked polymers (NDA-100), and chemically modified adsorbents (NDA-150 and NDA-99), were comparatively used to investigate the adsorption properties including equilibria, thermodynamics and kinetics. First, all of the results about equilibria show that the adsorption data fit well to the Freundlich model. The adsorption capacity of NDA-99 and NDA-150 especially for phenol is larger in a certain extent than other three types of polymers. The hydrophobic interaction from large specific surface was mainly occurred, while the polar groups containing oxygen and amine markedly enhance the adsorption process via hydrogen interaction. Furthermore, the adsorption amount for NDA-99 and XAD-4 decrease linearly with the solubility of solutes tested. Then, the negative values of enthalpy demonstrate the predominantly exothermic and physical solid-extraction processes. Finally, the relatively more rapid adsorption process could be found onto NDA-150 than NDA-99, with the reason of the double larger pore size of the former. In conclusion, solubility of solute, together with surface area, pore size and modified groups, extremely exerts influences to the adsorption performances

  19. Long-range charge transport in single G-quadruplex DNA molecules

    DEFF Research Database (Denmark)

    Livshits, Gideon I.; Stern, Avigail; Rotem, Dvir;

    2014-01-01

    -ups, and transporting significant current through individual DNA-based molecules remains a considerable challenge. Here, we report reproducible charge transport in guanine-quadruplex (G4) DNA molecules adsorbed on a mica substrate. Currents ranging from tens of picoamperes to more than 100 pA were measured in the G4...

  20. Single PTCDA molecules on planar and stepped KCl and NaCl(100) surfaces

    Science.gov (United States)

    Aldahhak, H.; Schmidt, W. G.; Rauls, E.

    2015-11-01

    First principles calculations have been employed to investigate the adsorption of single PTCDA molecules on KCl(100) and NaCl(100) surfaces. The lateral and rotational diffusion barriers as well as the electronic and the geometric aspects of single PTCDA molecules adsorbed on planar terraces as well as at defective steps have been studied in detail.

  1. Hindered rotation of a copper phthalocyanine molecule on C60 : Experiments and molecular mechanics calculations

    NARCIS (Netherlands)

    Fendrich, M.; Wagner, Th.; Stöhr, M.; Möller, R.

    2006-01-01

    If copper phthalocyanine (CuPc) molecules are deposited on a Au(111) surface covered with a monolayer of C60, the molecules are found to adsorb individually onto the close-packed layer of C60. As the adsorption site of the CuPc is not symmetric with respect to the underlying C60 layer, the CuPc mole

  2. Binary competitive adsorption of naphthalene compounds onto an aminated hypercrosslinked macroporous polymeric adsorbent

    Institute of Scientific and Technical Information of China (English)

    LIU Fu-qiang; CHEN Jin-long; CHENG Xiu-mei; GE Jun-jie; LI Ai-min; ZHANG Quan-xing

    2004-01-01

    An aminated hypercrosslinked macroporous polymeric adsorbent was synthesized and characterized. Adsorption isotherms for 1-amino-2-naphthol-4-sulfonic acid(1, 2, 4-acid) and 2-naphthol obtained from various binary adsorption environments can be well fitted by Freundlich equation, which indicated a favorable adsorption process in the studied range. Adsorption for 1, 2, 4-acid was an endothermic process in comparison with that for 2-naphthol of an exothermic process. 2-naphthol molecules put a little influence on the adsorption capacity for 1, 2, 4-acid. However, the adsorption to 1, 2, 4-acid depressed that to 2-naphthol in a large extent for the stronger electrostatic interaction between 1, 2, 4-acid and adsorbent. The predominant mechanism can be contributed to the competition for adsorption sites. And the simultaneous environment was confirmed to be helpful to the selective adsorption towards 1,2,4-acid based on the larger selectivity index.

  3. Structural, electronic, and magnetic properties of pristine and oxygen-adsorbed graphene nanoribbons

    International Nuclear Information System (INIS)

    The structural, electronic and magnetic properties of pristine and oxygen-adsorbed (3,0) zigzag and (6,1) armchair graphene nanoribbons have been investigated theoretically, by employing the ab initio pseudopotential method within the density functional scheme. The zigzag nanoribbon is more stable with antiferromagnetically coupled edges, and is semiconducting. The armchair nanoribbon does not show any preference for magnetic ordering and is semiconducting. The oxygen molecule in its triplet state is adsorbed most stably at the edge of the zigzag nanoribbon. The Stoner metallic behaviour of the ferromagnetic nanoribbons and the Slater insulating (ground state) behaviour of the antiferromagnetic nanoribbons remain intact upon oxygen adsorption. However, the local magnetic moment of the edge carbon atom of the ferromagnetic zigzag ribbon is drastically reduced, due to the formation of a spin-paired C-O bond.

  4. Effects of polymer coating on the adsorption of gas molecules on carbon nanotube networks

    International Nuclear Information System (INIS)

    Functionalization of carbon nanotubes (CNTs) with polymers such as polyethyleneimine or nafion was found to not change the adsorption properties of gas molecules on CNTs, although functionalization can remarkably enhance the sensitivity of gas sensors. Charge transfer between adsorbed molecules and single-walled carbon nanotubes (SWCNTs) at defect sites causes a steep and nonlinear conductance change at low gas concentrations, while molecules physically adsorbed on the pristine surfaces result in the linear electrical responses at higher concentrations. In addition, the molecular binding energies at defect sites of SWCNTs were measured to be 0.61 eV for NO2 and 0.53 eV for NH3

  5. Adlayer structure of TCNQ molecules on Cu(111): an in situ STM study

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In situ electrochemical scanning tunneling microscopy (STM) was employed to examine tetracyano- quinodimethane (TCNQ) layer adsorbed on Cu(111) electrode surface in 0.1 mol/L HClO4 solution. The TCNQ molecules are found to form highly-ordered long range adlayer with a (4×4) symmetry. Each TCNQ molecule is adsorbed on Cu(111) surface in flat-lying orientation. The molecules are preferentially aligned with their long axes in the [ ] di-rection. A structural model is proposed for the adlayer.

  6. Hazards of explosives dusts: Particle size effects

    Energy Technology Data Exchange (ETDEWEB)

    Cashdollar, K L; Hertzberg, M; Green, G M

    1992-02-01

    At the request of the Department of Energy, the Bureau of Mines has investigated the hazards of military explosives dispersed as dust clouds in a 20-L test chamber. In this report, the effect of particle size for HMX, HNS, RDX, TATB, and TNT explosives dusts is studied in detail. The explosibility data for these dusts are also compared to those for pure fuel dusts. The data show that all of the sizes of the explosives dusts that were studied were capable of sustaining explosions as dust clouds dispersed in air. The finest sizes (<10 [mu]m) of explosives dusts were less reactive than the intermediate sizes (20 to 60 [mu]m); this is opposite to the particle size effect observed previously for the pure fuel dusts. At the largest sizes studied, the explosives dusts become somewhat less reactive as dispersed dust clouds. The six sizes of the HMX dust were also studied as dust clouds dispersed in nitrogen.

  7. Comparative study of normal and branched alkane monolayer films adsorbed on a solid surface. I. Structure

    DEFF Research Database (Denmark)

    Enevoldsen, Ann Dorrit; Hansen, Flemming Yssing; Diama, A.;

    2007-01-01

    The structure of a monolayer film of the branched alkane squalane (C30H62) adsorbed on graphite has been studied by neutron diffraction and molecular dynamics (MD) simulations and compared with a similar study of the n-alkane tetracosane (n-C24H52). Both molecules have 24 carbon atoms along...... their backbone and squalane has, in addition, six methyl side groups. Upon adsorption, there are significant differences as well as similarities in the behavior of these molecular films. Both molecules form ordered structures at low temperatures; however, while the melting point of the two-dimensional (2D...... temperature. The neutron diffraction data show that the translational order in the squalane monolayer is significantly less than in the tetracosane monolayer. The authors' MD simulations suggest that this is caused by a distortion of the squalane molecules upon adsorption on the graphite surface. When...

  8. Anomalous Enhancement of Mechanical Properties in the Ammonia Adsorbed Defective Graphene

    Science.gov (United States)

    Ma, Fengxian; Jiao, Yalong; Gu, Yuantong; Bilic, Ante; Chen, Ying; Chen, Zhongfang; Du, Aijun

    2016-01-01

    Pure graphene is known as the strongest material ever discovered. However, the unavoidable defect formation in the fabrication process renders the strength of defective graphene much lower (~14%) than that of its perfect counterpart. By means of density functional theory computations, we systematically explored the effect of gas molecules (H2, N2, NH3, CO, CO2 and O2) adsorption on the mechanical strength of perfect/defective graphene. The NH3 molecule is found to play a dominant role in enhancing the strength of defective graphene by up to ~15.6%, while other gas molecules decrease the strength of graphene with varying degrees. The remarkable strength enhancement can be interpreted by the decomposition of NH3, which saturates the dangling bond and leads to charge redistribution at the defect site. The present work provides basic information for the mechanical failure of gas-adsorbed graphene and guidance for manufacturing graphene-based electromechanical devices. PMID:27667709

  9. On the HSAB based estimate of charge transfer between adsorbates and metal surfaces

    International Nuclear Information System (INIS)

    Graphical abstract: Left: molecule-to-metal electron charge transfer (ΔN) is proportional to the difference between the metal’s work function and molecular electronegativity. Right: correlation between the work function and explicitly DFT calculated ΔN. Highlights: ► HSAB based electron transfer parameter, ΔN, is analyzed for adsorbates on metal surfaces. ► ΔN gives reasonably estimated trends of charge transfer for atomic and molecular adsorbates. ► Adatom-metal bond strength is linearly proportional to metal-to-adatom charge transfer. ► DFT calculated adsorption energies of the N, O, and Cl adatoms on 11 different metals. ► DFT calculated work functions of low Miller index surfaces for 11 different metals. - Abstract: The applicability of the HSAB based electron charge transfer parameter, ΔN, is analyzed for molecular and atomic adsorbates on metal surfaces by means of explicit DFT calculations. For molecular adsorbates ΔN gives reasonable trends of charge transfer if work function is used for electronegativity of metal surface. For this reason, calculated work functions of low Miller index surfaces for 11 different metals are reported. As for reactive atomic adsorbates, e.g., N, O, and Cl, the charge transfer is proportional to the adatom valence times the electronegativity difference between the metal surface and the adatom, where the electronegativity of metal is represented by a linear combination of atomic Mulliken electronegativity and the work function of metal surface. It is further shown that the adatom-metal bond strength is linearly proportional to the metal-to-adatom charge transfer thus making the ΔN parameter a useful indicator to anticipate the corresponding adsorption energy trends.

  10. Underwater explosions and cavitation phenomena

    International Nuclear Information System (INIS)

    Some aspects of underwater explosions and cavitation phenomena have been studied by using a thermodynamic equation of state for water and a one-dimensional Lagrangian hydrocode. The study showed that surface cavitation is caused by the main blast wave and a bubble pulse from rebound of a release wave moving toward the center of the exploding bubble. Gravity has little effect on the surface cavitation. In nuclear explosions the bubble is bounded by a two-phase region rather than a gas-water interface. The two-phase region cavitates as the bubble expands, changing the optical absorption coefficient by many orders of magnitude and significantly affecting the optical signature. In assessing cavitation damage, it is concluded that a water jet of unstable bubble collapse erodes solid walls. The study leads to suggestions for future research

  11. RANCHERO explosive pulsed power experiments

    CERN Document Server

    Goforth, J H; Armijo, E V; Atchison, W L; Bartos, Yu; Clark, D A; Day, R D; Deninger, W J; Faehl, R J; Fowler, C M; García, F P; García, O F; Herrera, D H; Herrera, T J; Keinigs, R K; King, J C; Lindemuth, I R; López, E; Martínez, E C; Martínez, D; McGuire, J A; Morgan, D; Oona, H; Oro, D M; Parker, J V; Randolph, R B; Reinovsky, R E; Rodríguez, G; Stokes, J L; Sena, F C; Tabaka, L J; Tasker, D G; Taylor, A J; Torres, D T; Anderson, H D; Broste, W B; Johnson, J B; Kirbie, H C

    1999-01-01

    The authors are developing the RANCHERO high explosive pulsed power (HEPP) system to power cylindrically imploding solid-density liners for hydrodynamics experiments. Their near-term goal is to conduct experiments in the regime pertinent to the Atlas capacitor bank. That is, they will attempt to implode liners of ~50 g mass at velocities approaching 15 km/sec. The basic building block of the HEPP system is a coaxial generator with a 304.8 mm diameter stator, and an initial armature diameter of 152 mm. The armature is expanded by a high explosive (HE) charge detonated simultaneously along its axis. The authors have reported a variety of experiments conducted with generator modules 43 cm long and have presented an initial design for hydrodynamic liner experiments. In this paper, they give a synopsis of their first system test, and a status report on the development of a generator module that is 1.4 m long. (6 refs).

  12. Waves from an underground explosion

    Science.gov (United States)

    Krymskii, A. V.; Lyakhov, G. M.

    1984-05-01

    The problem of the propagation of a spherical detonation wave in water-saturated soil was solved in [1, 2] by using a model of a liquid porous multicomponent medium with bulk viscosity. Experiments show that soils which are not water saturated are solid porous multicomponent media having a viscosity, nonlinear bulk compression limit diagrams, and irreversible deformations. Taking account of these properties, and using the model in [2], we have solved the problem of the propagation of a spherical detonation wave from an underground explosion. The solution was obtained by computer, using the finite difference method [3]. The basic wave parameters were determined at various distances from the site of the explosion. The values obtained are in good agreement with experiment. Models of soils as viscous media which take account of the dependence of deformations on the rate of loading were proposed in [4 7] also. In [8] a model was proposed corresponding to a liquid multicomponent medium with a variable viscosity.

  13. Manipulation of adsorbed atoms and creation of new structures on room-temperature surfaces with a scanning tunneling microscope.

    Science.gov (United States)

    Whitman, L J; Stroscio, J A; Dragoset, R A; Celotta, R J

    1991-03-01

    A general method of manipulating adsorbed atoms and molecules on room-temperature surfaces with the use of a scanning tunneling microscope is described. By applying an appropriate voltage pulse between the sample and probe tip, adsorbed atoms can be induced to diffuse into the region beneath the tip. The field-induced diffusion occurs preferentially toward the tip during the voltage pulse because of the local potential energy gradient arising from the interaction of the adsorbate dipole moment with the electric field gradient at the surface. Depending upon the surface and pulse parameters, cesium (Cs) structures from one nanometer to a few tens of nanometers across have been created in this way on the (110) surfaces of gallium arsenide (GaAs) and indium antimonide (InSb), including structures that do not naturally occur.

  14. LEED crystallography studies of the structure of clean and adsorbate-covered Ir, Pt and Rh crystal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Koestner, R.J.

    1982-08-01

    There have only been a few Low Energy Electron Diffraction (LEED) intensity analyses carried out to determine the structure of molecules adsorbed on metal surfaces; most surface crystallography studies concentrated on the structure of clean unreconstructed or atomic adsorbate-covered transition metal faces. The few molecular adsorption systems already investigated by dynamical LEED are CO on Ni(100), Cu(100) and Pd(100) as well as C/sub 2/H/sub 2/ and C/sub 2/H/sub 4/ adsorbed on Pt(111). The emphasis of this thesis research has been to extend the applicability of LEED crystallography to the more complicated unit cells found in molecular overlayers on transition metals or in there constructed surfaces of clean transition metals.

  15. Density-functional theory study of interactions between water and carbon monoxide adsorbed on platinum under electrochemical conditions

    Science.gov (United States)

    Santana, Juan A.; Ishikawa, Yasuyuki

    2009-08-01

    In the study of CO poisoning of the platinum-based hydrogen anode in the polymer electrolyte fuel cell, a key issue that has eluded our understanding is the interactions of CO adsorbed on Pt surfaces and solvent H 2O. Our density-functional theory calculations reveal a new interpretation of the adsorbed state of CO and its interaction with water under electrochemical conditions, which rationalizes the observed quantitative relationship between infrared intensities for adsorbed bridging CO (bridge) and water exhibiting a high-frequency O-H stretch (ca. 3650 cm -1). The theoretical modeling indicates that the observed feature is due to a water molecule firmly hydrogen-bonded to CO (bridge).

  16. EXPLOSION RISK ASSESSMENTS FOR FACILITIES

    Directory of Open Access Journals (Sweden)

    Martin KULICH

    2015-12-01

    Full Text Available In the first part of the article we discuss the possibilities and analytical tools that can deal with the classification of space into zones with danger of explosion for devices with the presence of compressed flammable gases. Then we continue with specifications of possibilities for practical utilization linked to variables such as ventilation degree, hypothetical volume etc., including the examples. At the end we also give a brief overview of software for modelling gas leak, including examples of an outcome.

  17. Explosive Formulation Code Naming SOP

    Energy Technology Data Exchange (ETDEWEB)

    Martz, H. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2014-09-19

    The purpose of this SOP is to provide a procedure for giving individual HME formulations code names. A code name for an individual HME formulation consists of an explosive family code, given by the classified guide, followed by a dash, -, and a number. If the formulation requires preparation such as packing or aging, these add additional groups of symbols to the X-ray specimen name.

  18. Causes of the Cambrian Explosion.

    OpenAIRE

    Smith, M P; Harper, D.A.T.

    2013-01-01

    In the last decade, at least thirty individual hypotheses have been invoked to explain the Cambrian Explosion, ranging from starbursts in the Milky Way to intrinsic genomic reorganization and developmental patterning. It has been noted (1) that recent hypotheses fall into three categories: a) developmental/genetic, b) ecologic and c) abiotic environmental, with geochemical hypotheses forming an abundant and distinctive subset of the last. With a few notable exceptions, a significant majority ...

  19. Nuclear Explosions 1945-1998

    International Nuclear Information System (INIS)

    The main part of this report is a list of nuclear explosions conducted by the United States, the Soviet Union, the United Kingdom, France, China, India and Pakistan in 1945-98. The list includes all known nuclear test explosions and is compiled from a variety of sources including officially published information from the USA, Russia and France. The details given for each explosion (date, origin time, location, yield, type, etc.) are often compiled from more than one source because the individual sources do not give complete information. The report includes a short background to nuclear testing and provides brief information on the Comprehensive Nuclear-Test-Ban Treaty and the verification regime now being established to verify compliance with the treaty. It also summarizes nuclear testing country by country. The list should be used with some caution because its compilation from a variety of sources means that some of the data could be incorrect. This report is the result of cooperation between the Defence Research Establishment (FOA) and the Stockholm International Peace Research Institute (SIPRI)

  20. Nuclear Explosions 1945-1998

    Energy Technology Data Exchange (ETDEWEB)

    Bergkvist, Nils-Olov; Ferm, Ragnhild

    2000-07-01

    The main part of this report is a list of nuclear explosions conducted by the United States, the Soviet Union, the United Kingdom, France, China, India and Pakistan in 1945-98. The list includes all known nuclear test explosions and is compiled from a variety of sources including officially published information from the USA, Russia and France. The details given for each explosion (date, origin time, location, yield, type, etc.) are often compiled from more than one source because the individual sources do not give complete information. The report includes a short background to nuclear testing and provides brief information on the Comprehensive Nuclear-Test-Ban Treaty and the verification regime now being established to verify compliance with the treaty. It also summarizes nuclear testing country by country. The list should be used with some caution because its compilation from a variety of sources means that some of the data could be incorrect. This report is the result of cooperation between the Defence Research Establishment (FOA) and the Stockholm International Peace Research Institute (SIPRI)

  1. Thermodynamic States in Explosion Fields

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, A L

    2010-03-12

    We investigate the thermodynamic states occurring in explosion fields from condensed explosive charges. These states are often modeled with a Jones-Wilkins-Lee (JWL) function. However, the JWL function is not a Fundamental Equation of Thermodynamics, and therefore cannot give a complete specification of such states. We use the Cheetah code of Fried to study the loci of states of the expanded detonation products gases from C-4 charges, and their combustion products air. In the Le Chatelier Plane of specific-internal-energy versus temperature, these loci are fit with a Quadratic Model function u(T), which has been shown to be valid for T < 3,000 K and p < 1k-bar. This model is used to derive a Fundamental Equation u(v,s) for C-4. Given u(v,s), one can use Maxwell's Relations to derive all other thermodynamic functions, such as temperature: T(v,s), pressure: p(v,s), enthalpy: h(v,s), Gibbs free energy: g(v,s) and Helmholz free energy: f(v,s); these loci are displayed in figures for C-4. Such complete equations of state are needed for numerical simulations of blast waves from explosive charges, and their reflections from surfaces.

  2. Optimizing heterosurface adsorbent synthesis for liquid chromatography

    Science.gov (United States)

    Bogoslovskii, S. Yu.; Serdan, A. A.

    2016-03-01

    The structural and geometric parameters of a silica matrix (SM) for the synthesis of heterosurface adsorbents (HAs) are optimized. Modification is performed by shielding the external surfaces of alkyl-modified silica (AS) using human serum albumin and its subsequent crosslinking. The structural and geometric characteristics of the SM, AS, and HA are measured via low-temperature nitrogen adsorption. It is found that the structural characteristics of AS pores with diameters D 9 nm reduces significantly due to adsorption of albumin. It is concluded that silica gel with a maximum pore size distribution close to 5 nm and a minimal proportion of pores with D > 9 nm is optimal for HA synthesis; this allows us to achieve the greatest similarity between the chromatographic retention parameters for HA and AS. The suitability of the synthesized adsorbents for analyzing drugs in biological fluids through direct sample injection is confirmed by chromatography. It was found that the percentage of the protein fraction detected at the outlet of the chromatographic column is 98%.

  3. Dye sequestration using agricultural wastes as adsorbents

    Directory of Open Access Journals (Sweden)

    Kayode Adesina Adegoke

    2015-12-01

    Full Text Available Color is a visible pollutant and the presence of even minute amounts of coloring substance makes it undesirable due to its appearance. The removal of color from dye-bearing effluents is a major problem due to the difficulty in treating such wastewaters by conventional treatment methods. The most commonly used methods for color removal are biological oxidation and chemical precipitation. However, these processes are effective and economic only in the case where the solute concentrations are relatively high. Most industries use dyes and pigments to color their products. The presence of dyes in effluents is a major concern due to its adverse effect on various forms of life. The discharge of dyes in the environment is a matter of concern for both toxicological and esthetical reasons. It is evident from a literature survey of about 283 recently published papers that low-cost adsorbents have demonstrated outstanding removal capabilities for dye removal and the optimal equilibrium time of various dyes with different charcoal adsorbents from agricultural residues is between 4 and 5 h. Maximum adsorptions of acidic dyes were obtained from the solutions with pH 8–10. The challenges and future prospects are discussed to provide a better framework for a safer and cleaner environment.

  4. The persistence length of adsorbed dendronized polymers.

    Science.gov (United States)

    Grebikova, Lucie; Kozhuharov, Svilen; Maroni, Plinio; Mikhaylov, Andrey; Dietler, Giovanni; Schlüter, A Dieter; Ullner, Magnus; Borkovec, Michal

    2016-07-21

    The persistence length of cationic dendronized polymers adsorbed onto oppositely charged substrates was studied by atomic force microscopy (AFM) and quantitative image analysis. One can find that a decrease in the ionic strength leads to an increase of the persistence length, but the nature of the substrate and of the generation of the side dendrons influence the persistence length substantially. The strongest effects as the ionic strength is being changed are observed for the fourth generation polymer adsorbed on mica, which is a hydrophilic and highly charged substrate. However, the observed dependence on the ionic strength is much weaker than the one predicted by the Odijk, Skolnik, and Fixman (OSF) theory for semi-flexible chains. Low-generation polymers show a variation with the ionic strength that resembles the one observed for simple and flexible polyelectrolytes in solution. For high-generation polymers, this dependence is weaker. Similar dependencies are found for silica and gold substrates. The observed behavior is probably caused by different extents of screening of the charged groups, which is modified by the polymer generation, and to a lesser extent, the nature of the substrate. For highly ordered pyrolytic graphite (HOPG), which is a hydrophobic and weakly charged substrate, the electrostatic contribution to the persistence length is much smaller. In the latter case, we suspect that specific interactions between the polymer and the substrate also play an important role. PMID:27353115

  5. Detecting the dipole moment of a single carbon monoxide molecule

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, A., E-mail: aschwarz@physnet.uni-hamburg.de; Köhler, A.; Grenz, J.; Wiesendanger, R. [Physics Department, Institute of Applied Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg (Germany)

    2014-07-07

    Using non-contact atomic force microscopy with metallic tips enabled us to detect the electrostatic dipole moment of single carbon monoxide (CO) molecules adsorbed on three very different substrates. The observed distance dependent contrast can be explained by an interplay between the attractive van der Waals interaction and the repulsive electrostatic interaction, respectively, with the latter stemming from antiparallel aligned dipoles in tip and molecule. Our results suggest that metallic as well as CO-functionalized tips are able to probe electrostatic properties of polar molecules and that repulsive dipole-dipole interactions have to be considered when interpreting complex contrast patterns.

  6. Investigation of drug-porous adsorbent interactions in drug mixtures with selected porous adsorbents.

    Science.gov (United States)

    Madieh, Shadi; Simone, Michael; Wilson, Wendy; Mehra, Dev; Augsburger, Larry

    2007-04-01

    The adsorption of drugs onto porous substrates may prove to be a convenient method by which to enhance the dissolution rate of certain poorly water-soluble drugs in body fluids. The purpose of this research is to provide a better understanding of the type of interactions occurring between drugs and certain pharmaceutically acceptable porous adsorbents that leads to enhanced drug dissolution rates. The interactions between ibuprofen (acidic drug), acetaminophen (acidic drug), dipyridamole (basic drug), and the porous adsorbents used (calcium silicate and silica gel) were investigated using differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and Fourier Transform infrared spectroscopy (FTIR). DSC and PXRD results indicated a significant loss of crystallinity of both ibuprofen and acetaminophen but not dipyridamole. In the case of ibuprofen, FTIR results indicated the ionization of the carboxylic group based on the shift in the FTIR carboxylic band. Dissolution of ibuprofen from its mixtures with porous adsorbents was found to be significantly higher compared to the neat drug, whereas dipyridamole dissolution from its mixtures with porous adsorbents was not significantly different from that of the neat drug. PMID:17221849

  7. Determination of Nanogram Microparticles from Explosives after Real Open-Air Explosions by Confocal Raman Microscopy.

    Science.gov (United States)

    Zapata, Félix; García-Ruiz, Carmen

    2016-07-01

    Explosives are increasingly being used for terrorist attacks to cause devastating explosions. The detection of their postblast residues after an explosion is a high challenge, which has been barely investigated, particularly using spectroscopic techniques. In this research, a novel methodology using confocal Raman microscopy has been developed for the analysis of postblast residues from 10 open-air explosions caused by 10 different explosives (TNT, RDX, PETN, TATP, HMTD, dynamite, black powder, ANFO, chloratite, and ammonal) commonly used in improvised explosive devices. The methodology for the determination of postblast particles from explosives consisted of examining the samples surfaces with both the naked eye, first, and microscopically (10× and 50×), immediately afterward; and finally, analyzing the selected residues by confocal Raman spectroscopy in order to identify the postblast particles from explosives. Interestingly, confocal Raman microscopy has demonstrated to be highly suitable to rapidly, selectively, and noninvasively analyze postblast microscopic particles from explosives up to the nanogram range.

  8. Adsorbent Alkali Conditioning for Uranium Adsorption from Seawater. Adsorbent Performance and Technology Cost Evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Tsouris, Costas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Mayes, Richard T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Janke, Christopher James [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Dai, Sheng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Das, S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Liao, W. -P. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wood, Jordana [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gill, Gary [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Byers, Maggie Flicker [Univ. of Texas, Austin, TX (United States); Schneider, Eric [Univ. of Texas, Austin, TX (United States)

    2015-09-30

    The Fuel Resources program of the Fuel Cycle Research and Development program of the Office of Nuclear Energy (NE) is focused on identifying and implementing actions to assure that nuclear fuel resources are available in the United States. An immense source of uranium is seawater, which contains an estimated amount of 4.5 billion tonnes of dissolved uranium. This unconventional resource can provide a price cap and ensure centuries of uranium supply for future nuclear energy production. NE initiated a multidisciplinary program with participants from national laboratories, universities, and research institutes to enable technical breakthroughs related to uranium recovery from seawater. The goal is to develop advanced adsorbents to reduce the seawater uranium recovery technology cost and uncertainties. Under this program, Oak Ridge National Laboratory (ORNL) has developed a new amidoxime-based adsorbent of high surface area, which tripled the uranium capacity of leading Japanese adsorbents. Parallel efforts have been focused on the optimization of the physicochemical and operating parameters used during the preparation of the adsorbent for deployment. A set of parameters that need to be optimized are related to the conditioning of the adsorbent with alkali solution, which is necessary prior to adsorbent deployment. Previous work indicated that alkali-conditioning parameters significantly affect the adsorbent performance. Initiated in 2014, this study had as a goal to determine optimal parameters such as base type and concentration, temperature, and duration of conditioning that maximize the uranium adsorption performance of amidoxime functionalized adsorbent, while keeping the cost of uranium production low. After base-treatment at various conditions, samples of adsorbent developed at ORNL were tested in this study with batch simulated seawater solution of 8-ppm uranium concentration, batch seawater spiked with uranium nitrate at 75-100 ppb uranium, and continuous

  9. Photoluminescent Detection of Dissolved Underwater Trace Explosives

    Directory of Open Access Journals (Sweden)

    Tye Langston

    2010-01-01

    Full Text Available A portable, rapid, and economical method for in situ trace explosive detection in aqueous solutions was demonstrated using photoluminescence. Using europium/thenoyltrifluoroacetone as the reagent, dissolved nitroglycerin was fluorescently tagged and detected in seawater solutions without sample preparation, drying, or preconcentration. The chemical method was developed in a laboratory setting and demonstrated in a flow-through configuration using lightweight, inexpensive, commercial components by directly injecting the reagents into a continually flowing seawater stream using a small amount of organic solvent (approximately 8% of the total solution. Europium's vulnerability to vibrational fluorescence quenching by water provided the mode of detection. Without nitroglycerin in the seawater solution, the reagent's fluorescence was quenched, but when dissolved nitroglycerin was present, it displaced the water molecules from the europium/thenoyltrifluoroacetone compound and restored fluorescence. This effort focused on developing a seawater sensor, but performance comparisons were made to freshwater. The method was found to perform better in freshwater and it was shown that certain seawater constituents (such as calcium have an adverse impact. However, the concentrations of these constituents are not expected to vary significantly from the natural seawater used herein.

  10. Data base of chemical explosions in Kazakhstan

    Energy Technology Data Exchange (ETDEWEB)

    Demin, V.N. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan); Malahova, M.N. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan); Martysevich, P.N. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan); Mihaylova, N.N. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan); Nurmagambetov, A. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan); Kopnichev, Yu.F. D. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan); Edomin, V.I. [National Nuclear Center of Republic of Kazakhstan Institute of Geophysical Researches (Kazakhstan)

    1996-12-01

    Within the bounds of this report, the following works were done: (1) Information about explosion quarries, located in Southern, Eastern and Northern Kasakstan was summarized. (2) The general information about seismicity of areas of location of explosion quarries was adduced. (3) The system of observation and seismic apparatus, recording the local earthquakes and quarry explosions at the territory of Kazakstan were described. (4) Data base of quarry explosions, that were carried out in Southern, Eastern and Northern Kazakstan during 1995 and first half of 1996 year was adduced. (5) Upon the data of registration of explosions in Southern Kazakstan the correlative dependences between power class of explosions and summary weight of charge were constructed. (6) Seismic records of quarry explosions were adduced. It is necessary to note, that the collection of data about quarry explosions in Kazakstan in present time is very difficult task. Organizations, that makes these explosions, are always suffering reorganizations and sometimes it is actually impossible to receive all the necessary information. Some quarries are situated in remote, almost inaccessible regions, and within the bounds of supplier financing not the every quarry was in success to visit. So the present data base upon the chemical explosions for 1995 is not full and in further it`s expansion is possible.

  11. Global structure search for molecules on surfaces: Efficient sampling with curvilinear coordinates.

    Science.gov (United States)

    Krautgasser, Konstantin; Panosetti, Chiara; Palagin, Dennis; Reuter, Karsten; Maurer, Reinhard J

    2016-08-28

    Efficient structure search is a major challenge in computational materials science. We present a modification of the basin hopping global geometry optimization approach that uses a curvilinear coordinate system to describe global trial moves. This approach has recently been shown to be efficient in structure determination of clusters [C. Panosetti et al., Nano Lett. 15, 8044-8048 (2015)] and is here extended for its application to covalent, complex molecules and large adsorbates on surfaces. The employed automatically constructed delocalized internal coordinates are similar to molecular vibrations, which enhances the generation of chemically meaningful trial structures. By introducing flexible constraints and local translation and rotation of independent geometrical subunits, we enable the use of this method for molecules adsorbed on surfaces and interfaces. For two test systems, trans-β-ionylideneacetic acid adsorbed on a Au(111) surface and methane adsorbed on a Ag(111) surface, we obtain superior performance of the method compared to standard optimization moves based on Cartesian coordinates.

  12. Global structure search for molecules on surfaces: Efficient sampling with curvilinear coordinates

    Science.gov (United States)

    Krautgasser, Konstantin; Panosetti, Chiara; Palagin, Dennis; Reuter, Karsten; Maurer, Reinhard J.

    2016-08-01

    Efficient structure search is a major challenge in computational materials science. We present a modification of the basin hopping global geometry optimization approach that uses a curvilinear coordinate system to describe global trial moves. This approach has recently been shown to be efficient in structure determination of clusters [C. Panosetti et al., Nano Lett. 15, 8044-8048 (2015)] and is here extended for its application to covalent, complex molecules and large adsorbates on surfaces. The employed automatically constructed delocalized internal coordinates are similar to molecular vibrations, which enhances the generation of chemically meaningful trial structures. By introducing flexible constraints and local translation and rotation of independent geometrical subunits, we enable the use of this method for molecules adsorbed on surfaces and interfaces. For two test systems, trans-β-ionylideneacetic acid adsorbed on a Au(111) surface and methane adsorbed on a Ag(111) surface, we obtain superior performance of the method compared to standard optimization moves based on Cartesian coordinates.

  13. Removal of formaldehyde by adsorption and plasma treatment of mineral adsorbent

    Science.gov (United States)

    Saulich, K.; Müller, S.

    2013-01-01

    Formaldehyde is a harmful ambient air pollutant which can be produced by incomplete combustion processes, e.g. in power plants or automobiles. In this work a cycled adsorption and discharge process using mineral granulate in a packed bed dielectric barrier discharge plasma reactor was applied for formaldehyde (99 ppm) removal from gas streams. The mineral granulate used consisted of 80% halloysite and showed a good adsorption capacity for formaldehyde. In the discharge step, the adsorbed formaldehyde molecules were decomposed to COx and hydrocarbons in a N2 plasma at a low input discharge power of 2.2 W. The decomposition performance on adsorbed formaldehyde molecules was studied depending on space-time, a specific oxygen fraction of the carrier gas and the influence of temperature. With rising N2 space times in the discharge area, the total amount of decomposed formaldehyde molecules increased and the decomposition reaction mechanism shifted to CO2 formation. An oxygen fraction in the carrier gas further raised the oxidized amount of formaldehyde to CO2. The mineral granulate showed satisfied regeneration ability during the cycled plasma process.

  14. Optimizing Conditions to Cholesterol Adsorbed with Carboxymethyl Chitosan

    OpenAIRE

    Mardiyah Kurniasih; Dwi Kartika; Riyanti Riyanti

    2016-01-01

    A research on optimizing conditions to cholesterol adsorbed have been performed. Optimization was performed by varying: contact time, adsorbent weight and temperature of the system's. A full factorial experimental design was used in this study. Characterization performed on the synthesized chitosan and carboxymethyl chitosan including FTIR, water content, ash content, solubility, porosity, and swelling effect. The results showed that carboxymethyl chitosan able to adsorb cholesterol under con...

  15. Renormalization of Molecular Quasiparticle Levels at Metal-Molecule Interfaces: Trends across Binding Regimes

    DEFF Research Database (Denmark)

    Thygesen, Kristian Sommer; Rubio, Angel

    2009-01-01

    When an electron or a hole is added into an orbital of an adsorbed molecule the substrate electrons will rearrange in order to screen the added charge. This polarization effect reduces the electron addition and removal energies of the adsorbed molecule relative to those of the free molecule. Using...... a microscopic model of the metal-molecule interface, we illustrate the basic features of this renormalization mechanism through systematic GW, Hartree-Fock, and Kohn-Sham calculations for the molecular energy levels as function of the model parameters. We identify two different polarization mechanisms: (i......) polarization of the metal (image charge formation) and (ii) polarization of the molecule via charge transfer across the interface. The importance of (i) and (ii) is found to increase with the metal density of states at the Fermi level and metal-molecule coupling strength, respectively....

  16. DESORPTION OF VOCs FROM POLYMERIC ADSORBENTS UNDER MICROWAVE FIELD

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Desorption of volatile organic compounds (VOCs)from polymeric adsorbents by microwave was investigated experimentally. Two kinds of organic compounds, benzene and toluene,were separately used as adsorbates in this work. Results showed that the application of microwave to regenerate the polymeric adsorbents not only can get higher regeneration efficiency in comparison with the use of heat regeneration, but also make the temperatures of the fixed beds much lower than that when using the heat regeneratton The weaker the polarity of a polymeric adsorbent, the easier its regeneration was.

  17. Multichannel Detection and Differentiation of Explosives with a Quantum Dot Array.

    Science.gov (United States)

    Peveler, William J; Roldan, Alberto; Hollingsworth, Nathan; Porter, Michael J; Parkin, Ivan P

    2016-01-26

    The sensing and differentiation of explosive molecules is key for both security and environmental monitoring. Single fluorophores are a widely used tool for explosives detection, but a fluorescent array is a more powerful tool for detecting and differentiating such molecules. By combining array elements into a single multichannel platform, faster results can be obtained from smaller amounts of sample. Here, five explosives are detected and differentiated using quantum dots as luminescent probes in a multichannel platform: 2,4-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), tetryl (2,4,6-trinitrophenylmethylnitramine), cyclotrimethylenetrinitramine (RDX), and pentaerythritol tetranitrate (PETN). The sharp, variable emissions of the quantum dots, from a single excitation wavelength, make them ideal for such a system. Each color quantum dot is functionalized with a different surface receptor via a facile ligation process. These receptors undergo nonspecific interactions with the explosives, inducing variable fluorescence quenching of the quantum dots. Pattern analysis of the fluorescence quenching data allows for explosive detection and identification with limits-of-detection in the ppb range. PMID:26579950

  18. Theoretical Insight of Physical Adsorption for a Single-Component Adsorbent + Adsorbate System: I. Thermodynamic Property Surfaces

    KAUST Repository

    Chakraborty, Anutosh

    2009-02-17

    Thermodynamic property surfaces for a single-component adsorbent + adsorbate system are derived and developed from the viewpoint of classical thermodynamics, thermodynamic requirements of chemical equilibrium, Gibbs law, and Maxwell relations. They enable us to compute the entropy and enthalpy of the adsorbed phase, the isosteric heat of adsorption, specific heat capacity, and the adsorbed phase volume thoroughly. These equations are very simple and easy to handle for calculating the energetic performances of any adsorption system. We have shown here that the derived thermodynamic formulations fill up the information gap with respect to the state of adsorbed phase to dispel the confusion as to what is the actual state of the adsorbed phase. We have also discussed and established the temperature-entropy diagrams of (i) CaCl 2-in-silica gel + water system for cooling applications, and (ii) activated carbon (Maxsorb III) + methane system for gas storage. © Copyright 2009 American Chemical Society.

  19. Simulation of inelastic electron tunneling spectroscopy of single molecules with functionalized tips

    OpenAIRE

    García-Lekue, Aran; Sánchez-Portal, Daniel; Arnau, Andrés; Frederiksen, T.

    2011-01-01

    The role of the tip in inelastic electron tunneling spectroscopy (IETS) performed with scanning tunneling microscopes (STM) is theoretically addressed via first-principles simulations of vibrational spectra of single carbon monoxide (CO) molecules adsorbed on Cu(111). We show how chemically functionalized STM tips modify the IETS intensity corresponding to adsorbate modes on the sample side. The underlying propensity rules are explained using symmetry considerations for both the vibrational m...

  20. Two distinctive energy migration pathways of monolayer molecules on metal nanoparticle surfaces

    OpenAIRE

    Li, Jiebo; Qian, Huifeng; Chen, Hailong; Zhao, Zhun; Yuan, Kaijun; Chen, Guangxu; Miranda, Andrea; Guo, Xunmin; Chen, Yajing; Zheng, Nanfeng; Michael S Wong; Zheng, Junrong

    2016-01-01

    Energy migrations at metal nanomaterial surfaces are fundamentally important to heterogeneous reactions. Here we report two distinctive energy migration pathways of monolayer adsorbate molecules on differently sized metal nanoparticle surfaces investigated with ultrafast vibrational spectroscopy. On a 5 nm platinum particle, within a few picoseconds the vibrational energy of a carbon monoxide adsorbate rapidly dissipates into the particle through electron/hole pair excitations, generating hea...

  1. Mobility of adsorbed Cry1Aa insecticidal toxin from Bacillus thuringiensis (Bt) on montmorillonite measured by fluorescence recovery after photobleaching (FRAP)

    Science.gov (United States)

    Helassa, Nordine; Daudin, Gabrielle; Noinville, Sylvie; Janot, Jean-Marc; Déjardin, Philippe; Staunton, Siobhán; Quiquampoix, Hervé

    2010-06-01

    The insecticidal toxins produced by genetically modified Bt crops are introduced into soil through root exudates and tissue decomposition and adsorb readily on soil components, especially on clays. This immobilisation and the consequent concentration of the toxins in "hot spots" could increase the exposure of soil organisms. Whereas the effects on non-target organisms are well documented, few studies consider the migration of the toxin in soil. In this study, the residual mobility of Bt Cry1Aa insecticidal toxin adsorbed on montmorillonite was assessed using fluorescence recovery after photobleaching (FRAP). This technique, which is usually used to study dynamics of cytoplasmic and membrane molecules in live cells, was applied for the first time to a protein adsorbed on a finely divided swelling clay mineral, montmorillonite. No mobility of adsorbed toxin was observed at any pH and at different degrees of surface saturation.

  2. Trends in adsorbate induced core level shifts

    Science.gov (United States)

    Nilsson, Viktor; Van den Bossche, Maxime; Hellman, Anders; Grönbeck, Henrik

    2015-10-01

    Photoelectron core level spectroscopy is commonly used to monitor atomic and molecular adsorption on metal surfaces. As changes in the electron binding energies are convoluted measures with different origins, calculations are often used to facilitate the decoding of experimental signatures. The interpretation could in this sense benefit from knowledge on trends in surface core level shifts for different metals and adsorbates. Here, density functional theory calculations have been used to systematically evaluate core level shifts for (111) and (100) surfaces of 3d, 4d, and 5d transition metals upon CO, H, O and S adsorption. The results reveal trends and several non-intuitive cases. Moreover, the difficulties correlating core level shifts with charging and d-band shifts are underlined.

  3. Linear transport models for adsorbing solutes

    Science.gov (United States)

    Roth, K.; Jury, W. A.

    1993-04-01

    A unified linear theory for the transport of adsorbing solutes through soils is presented and applied to analyze movement of napropamide through undisturbed soil columns. The transport characteristics of the soil are expressed in terms of the travel time distribution of the mobile phase which is then used to incorporate local interaction processes. This approach permits the analysis of all linear transport processes, not only the small subset for which a differential description is known. From a practical point of view, it allows the direct use of measured concentrations or fluxes of conservative solutes to characterize the mobile phase without first subjecting them to any model. For complicated flow regimes, this may vastly improve the identification of models and estimation of their parameters for the local adsorption processes.

  4. Thermal explosion in oscillating ambient conditions

    Science.gov (United States)

    Novozhilov, Vasily

    2016-07-01

    Thermal explosion problem for a medium with oscillating ambient temperature at its boundaries is considered. This is a new problem in thermal explosion theory, not previously considered in a distributed system formulation, but important for combustion and fire science. It describes autoignition of wide range of fires (such as but not limited to piles of biosolids and other organic matter; storages of munitions, explosives, propellants) subjected to temperature variations, such as seasonal or day/night variation. The problem is considered in formulation adopted in classical studies of thermal explosion. Critical conditions are determined by frequency and amplitude of ambient temperature oscillations, as well as by a number of other parameters. Effects of all the parameters on critical conditions are quantified. Results are presented for the case of planar symmetry. Development of thermal explosion in time is also considered, and a new type of unsteady thermal explosion development is discovered where thermal runaway occurs after several periods of temperature oscillations within the medium.

  5. Explosives Detection: Exploitation of the Physical Signatures

    Science.gov (United States)

    Atkinson, David

    2010-10-01

    Explosives based terrorism is an ongoing threat that is evolving with respect to implementation, configuration and materials used. There are a variety of devices designed to detect explosive devices, however, each technology has limitations and operational constraints. A full understanding of the signatures available for detection coupled with the array of detection choices can be used to develop a conceptual model of an explosives screening operation. Physics based sensors provide a robust approach to explosives detection, typically through the identification of anomalies, and are currently used for screening in airports around the world. The next generation of detectors for explosives detection will need to be more sensitive and selective, as well as integrate seamlessly with devices focused on chemical signatures. An appreciation for the details of the physical signature exploitation in cluttered environments with time, space, and privacy constraints is necessary for effective explosives screening of people, luggage, cargo, and vehicles.

  6. APPLICATION OF EXPLOSIVE ENERGY IN METALWORKING

    Directory of Open Access Journals (Sweden)

    Vječislav Bohanek

    2013-07-01

    Full Text Available When an explosive charge is detonate, considerable amount of energy in a very short period of time is released. Energy, released in this way, is used for performing various kinds of useful work. Most explosives are consumed to obtain mineral raw materials in the mining industry and for various excavations in the construction industry. One of the specific areas of application explosive energy is an area of explosive metalworking. Using energy of explosive metal is welded, formed, cuts, harden etc. This paper presents an overview of the existing explosive metalworking methods. Methods are explained and comparative advantages in comparison to conventional metalworking methods are given (the paper is published in Croatian.

  7. Isocyanide ligands adsorbed on metal surfaces: applications in catalysis, nanochemistry, and molecular electronics.

    Science.gov (United States)

    Angelici, Robert J; Lazar, Mihaela

    2008-10-20

    Knowledge of the coordination chemistry and reactivity of isocyanide ligands in transition-metal complexes forms the basis for understanding the adsorption and reactions of isocyanides on metal surfaces. In this overview, we explore reactions (often catalytic) of isocyanides adsorbed on metal surfaces that reflect their patterns of reactivity in metal complexes. We also examine applications of isocyanide adsorption to the stabilization of metal nanoparticles, the functionalization of metal electrodes, and the creation of conducting organic-metal junctions in molecule-scale electronic devices.

  8. Spontaneous symmetry breaking and strong deformations in metal adsorbed graphene sheets

    Science.gov (United States)

    Jalbout, A. F.; Ortiz, Y. P.; Seligman, T. H.

    2013-03-01

    We study the adsorption of Li to graphene flakes simulated as aromatic molecules. Surprisingly the out of plane deformation is much stronger for the double adsorption from both sides to the same ring than for a single adsorption, although a symmetric solution seems possible. We thus have an interesting case of spontaneous symmetry breaking. While we cannot rule out a Jahn Teller deformation with certainty, this explanation seems unlikely and other options are discussed. We find a similar behavior for boron-nitrogen sheets, and also for other light alkalines as adsorbants.

  9. Nanoscale probing of adsorbed species by tip-enhanced Raman spectroscopy

    OpenAIRE

    Pettinger, B.; Ren, B; G. Picardi; Schuster, R.; Ertl, G.

    2004-01-01

    Tip-enhanced Raman spectroscopy (TERS) is based on the optical excitation of localized surface plasmons in the tip-substrate cavity, which provides a large but local field enhancement near the tip apex. We report on TERS with smooth single crystalline surfaces as substrates. The adsorbates were CN– ions at Au(111) and malachite green isothiocyanate (MGITC) molecules at Au(111) and Pt(110) using either Au or Ir tips. The data analysis yields Raman enhancements of about 4x105 for CN– and up to ...

  10. Theory and Monte-Carlo simulation of adsorbates on corrugated surfaces

    DEFF Research Database (Denmark)

    Vives, E.; Lindgård, P.-A.

    1993-01-01

    Phase transitions in systems of adsorbed molecules on corrugated surfaces are studied by means of Monte Carlo simulation. Particularly, we have studied the phase diagram of D2 on graphite as a function of coverage and temperature. We have demonstrated the existence of an intermediate gamma......-phase between the commensurate and incommensurate phase stabilized by defects. Special attention has been given to the study of the epitaxial rotation angles of the different phases. Available experimental data is in agreement with the simulations and with a general theory for the epitaxial rotation which takes...

  11. Comparative study of normal and branched alkane monolayer films adsorbed on a solid surface. II. Dynamics

    DEFF Research Database (Denmark)

    Enevoldsen, Ann Dorrit; Hansen, Flemming Yssing; Diama, A.;

    2007-01-01

    The dynamics of monolayer films of the n-alkane tetracosane (n-C24H52) and the branched alkane squalane (C30H62) adsorbed on graphite have been studied by quasielastic and inelastic neutron scattering and molecular dynamics (MD) simulations. Both molecules have 24 carbon atoms along their carbon...... on very different time scales: 1-40 ps (DCS) and 0.1-4 ns (HFBS). The MD simulations were done on corresponding time scales and were used to interpret the neutron spectra. The authors found that the dynamics of the two monolayers are qualitatively similar on the respective time scales...

  12. Scanning tunneling microscopy I general principles and applications to clean and adsorbate-covered surfaces

    CERN Document Server

    Wiesendanger, Roland

    1992-01-01

    Scanning Tunneling Microscopy I provides a unique introduction to a novel and fascinating technique that produces beautiful images of nature on an atomic scale. It is the first of three volumes that together offer a comprehensive treatment of scanning tunneling microscopy, its diverse applications, and its theoretical treatment. In this volume the reader will find a detailed description of the technique itself and of its applications to metals, semiconductors, layered materials, adsorbed molecules and superconductors. In addition to the many representative results reviewed, extensive references to original work will help to make accessible the vast body of knowledge already accumulated in this field.

  13. Scanning tunneling microscopy and spectroscopy of functional molecules on metal surfaces

    OpenAIRE

    Ge, Xin

    2007-01-01

    This thesis is committed to the study of functional molecules adsorbed on metal surfaces by means of Low Temperature Scanning Tunneling Microscopy. It includes two main parts. In the first part the adsorption geometry of lander molecule (C90H98) on different metal surfaces is discussed. Three conformations as well as chiral structures of lander molecules on the terrace of Cu(100) are observed by STM. Electron scattering quantum chemical calculated results are compared with our experimental da...

  14. Calculation of images of oriented C_60 molecules using molecular orbital theory

    OpenAIRE

    Hands, Ian D; Dunn, Janette L; Bates, Colin A.

    2010-01-01

    Using Hückel molecular-orbital theory, images are created to represent the electron distributions expected for a C60 molecule adsorbed on a substrate. Three different orientations of the C60 molecule on the substrate are considered. The effect of the interaction of the molecule with the substrate is treated purely from the basis of symmetry using group theoretical methods. The resulting electron distributions are then used to generate idealized images which represent how the molec...

  15. Jahn-Teller effects in molecules on surfaces with specific application to C_60

    OpenAIRE

    Hands, Ian D; Dunn, Janette L; Rawlinson, Catherine S.A.; Bates, Colin A.

    2010-01-01

    Scanning tunnelling microscopy (STM) is capable of imaging molecules adsorbed onto surfaces with su±cient resolution as to permit intramolecular features to be discerned. Therefore, imaging molecules subject to the Jahn-Teller (JT) effect could, in principle, yield valuable information about the vibronic coupling responsible for the JT effect. However, such an application is not without its complications. For example, the JT effect causes subtle, dynamic distortions of the molecule; but...

  16. Computer code to predict the heat of explosion of high energy materials.

    Science.gov (United States)

    Muthurajan, H; Sivabalan, R; Pon Saravanan, N; Talawar, M B

    2009-01-30

    The computational approach to the thermochemical changes involved in the process of explosion of a high energy materials (HEMs) vis-à-vis its molecular structure aids a HEMs chemist/engineers to predict the important thermodynamic parameters such as heat of explosion of the HEMs. Such a computer-aided design will be useful in predicting the performance of a given HEM as well as in conceiving futuristic high energy molecules that have significant potential in the field of explosives and propellants. The software code viz., LOTUSES developed by authors predicts various characteristics of HEMs such as explosion products including balanced explosion reactions, density of HEMs, velocity of detonation, CJ pressure, etc. The new computational approach described in this paper allows the prediction of heat of explosion (DeltaH(e)) without any experimental data for different HEMs, which are comparable with experimental results reported in literature. The new algorithm which does not require any complex input parameter is incorporated in LOTUSES (version 1.5) and the results are presented in this paper. The linear regression analysis of all data point yields the correlation coefficient R(2)=0.9721 with a linear equation y=0.9262x+101.45. The correlation coefficient value 0.9721 reveals that the computed values are in good agreement with experimental values and useful for rapid hazard assessment of energetic materials. PMID:18513863

  17. Trace Detection of RDX, HMX and PETN Explosives Using a Fluorescence Spot Sensor

    Science.gov (United States)

    Wang, Chen; Huang, Helin; Bunes, Benjamin R.; Wu, Na; Xu, Miao; Yang, Xiaomei; Yu, Li; Zang, Ling

    2016-05-01

    1,3,5-trinitroperhydro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and pentaerythritol tetranitrate (PETN), the major components in plastic explosives, pose a significant threat to public safety. A quick, sensitive, and low-cost detection method for these non-volatile explosives is eagerly demanded. Here we present a fluo-spot approach, which can be employed for in situ detection of trace amount of explosives. The sensor molecule is a charge-transfer fluorophore, DCM, which is strongly fluorescent in its pristine state, but non-fluorescent after the quick reaction with NO2· (or NO2+) generated from the UV photolysis of RDX, HMX (or PETN). When fabricated within silica gel TLC plate, the fluo-spot sensor features high sensitivity owing to the large surface area and porous structure of the substrate. The sensor reaction mechanism was verified by various experimental characterizations, including chromatography, UV-Vis absorption and fluorescence spectroscopy, MS and 1H NMR spectrometry. The fluo-spot also demonstrated high selectivity towards RDX, HMX and PETN, as no significant fluorescence quenching was observed for other chemical compounds including common nitro-aromatic explosives and inorganic oxidative compounds. The DCM sensor can also be used as an economical spray kit to directly spot the explosives by naked eyes, implying great potential for quick, low-cost trace explosives detection.

  18. Computer code to predict the heat of explosion of high energy materials

    Energy Technology Data Exchange (ETDEWEB)

    Muthurajan, H. [Armament Research and Development Establishment, Pashan, Pune 411021 (India)], E-mail: muthurajan_h@rediffmail.com; Sivabalan, R.; Pon Saravanan, N.; Talawar, M.B. [High Energy Materials Research Laboratory, Sutarwadi, Pune 411 021 (India)

    2009-01-30

    The computational approach to the thermochemical changes involved in the process of explosion of a high energy materials (HEMs) vis-a-vis its molecular structure aids a HEMs chemist/engineers to predict the important thermodynamic parameters such as heat of explosion of the HEMs. Such a computer-aided design will be useful in predicting the performance of a given HEM as well as in conceiving futuristic high energy molecules that have significant potential in the field of explosives and propellants. The software code viz., LOTUSES developed by authors predicts various characteristics of HEMs such as explosion products including balanced explosion reactions, density of HEMs, velocity of detonation, CJ pressure, etc. The new computational approach described in this paper allows the prediction of heat of explosion ({delta}H{sub e}) without any experimental data for different HEMs, which are comparable with experimental results reported in literature. The new algorithm which does not require any complex input parameter is incorporated in LOTUSES (version 1.5) and the results are presented in this paper. The linear regression analysis of all data point yields the correlation coefficient R{sup 2} = 0.9721 with a linear equation y = 0.9262x + 101.45. The correlation coefficient value 0.9721 reveals that the computed values are in good agreement with experimental values and useful for rapid hazard assessment of energetic materials.

  19. Trace Detection of RDX, HMX and PETN Explosives Using a Fluorescence Spot Sensor.

    Science.gov (United States)

    Wang, Chen; Huang, Helin; Bunes, Benjamin R; Wu, Na; Xu, Miao; Yang, Xiaomei; Yu, Li; Zang, Ling

    2016-01-01

    1,3,5-trinitroperhydro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), and pentaerythritol tetranitrate (PETN), the major components in plastic explosives, pose a significant threat to public safety. A quick, sensitive, and low-cost detection method for these non-volatile explosives is eagerly demanded. Here we present a fluo-spot approach, which can be employed for in situ detection of trace amount of explosives. The sensor molecule is a charge-transfer fluorophore, DCM, which is strongly fluorescent in its pristine state, but non-fluorescent after the quick reaction with NO2· (or NO2(+)) generated from the UV photolysis of RDX, HMX (or PETN). When fabricated within silica gel TLC plate, the fluo-spot sensor features high sensitivity owing to the large surface area and porous structure of the substrate. The sensor reaction mechanism was verified by various experimental characterizations, including chromatography, UV-Vis absorption and fluorescence spectroscopy, MS and (1)H NMR spectrometry. The fluo-spot also demonstrated high selectivity towards RDX, HMX and PETN, as no significant fluorescence quenching was observed for other chemical compounds including common nitro-aromatic explosives and inorganic oxidative compounds. The DCM sensor can also be used as an economical spray kit to directly spot the explosives by naked eyes, implying great potential for quick, low-cost trace explosives detection. PMID:27146290

  20. New Dark Matter Detector using Nanoscale Explosives

    OpenAIRE

    Lopez, Alejandro; Drukier, Andrzej; Freese, Katherine; Kurdak, Cagliyan; Tarle, Gregory

    2014-01-01

    We present nanoscale explosives as a novel type of dark matter detector and study the ignition properties. When a Weakly Interacting Massive Particle WIMP from the Galactic Halo elastically scatters off of a nucleus in the detector, the small amount of energy deposited can trigger an explosion. For specificity, this paper focuses on a type of two-component explosive known as a nanothermite, consisting of a metal and an oxide in close proximity. When the two components interact they undergo a ...

  1. Analysis of TROI-13 Steam Explosion Experiment

    OpenAIRE

    Mitja Uršič; Matjaž Leskovar

    2008-01-01

    The prediction of steam explosion inducing loads in nuclear power plants must be based on results of experimental research programmes and on simulations using validated fuel-coolant interaction codes. In this work, the TROI-13 steam explosion experiment was analysed with the fuel-coolant interaction MC3D computer code. The TROI-13 experiment is one of several experiments performed in the TROI research program and resulted in a spontaneous steam explosion using corium melt. First, the TROI-13 ...

  2. Is a Cambrian Explosion Coming for Robotics?

    OpenAIRE

    Gill A. Pratt

    2015-01-01

    About half a billion years ago, life on earth experienced a short period of very rapid diversification called the "Cambrian Explosion." Many theories have been proposed for the cause of the Cambrian Explosion, one of the most provocative being the evolution of vision, allowing animals to dramatically increase their ability to hunt and find mates. Today, technological developments on several fronts are fomenting a similar explosion in the diversification and applicability of robotics. Many of ...

  3. Spectroscopy of surface adsorbed molecules (scanning tunneling microscopy). Progress report, May 1, 1985-April 30, 1986

    International Nuclear Information System (INIS)

    A review of the scanning tunneling microscopy program is given. This article contains a description of the design and fabrication of the microscope in addition to description of studies which use the microscope: studies of charge-density waves and studies of tunnel junctions doped with metals and semiconductors. 48 refs., 26 figs

  4. Modeling the binding of fulvic acid by goethite: The speciation of adsorbed FA molecules

    NARCIS (Netherlands)

    Filius, J.D.; Meeussen, J.C.L.; Hiemstra, T.; Riemsdijk, van W.H.

    2003-01-01

    Under natural conditions, the adsorption of ions at the solid-water interface may be strongly influenced by the adsorption of organic matter. In this paper, we describe the adsorption of fulvic acid (FA) by metal (hydr)oxide surfaces with a heterogeneous surface complexation model, the ligand and ch

  5. Shock Initiation of Damaged Explosives

    Energy Technology Data Exchange (ETDEWEB)

    Chidester, S K; Vandersall, K S; Tarver, C M

    2009-10-22

    Explosive and propellant charges are subjected to various mechanical and thermal insults that can increase their sensitivity over the course of their lifetimes. To quantify this effect, shock initiation experiments were performed on mechanically and thermally damaged LX-04 (85% HMX, 15% Viton by weight) and PBX 9502 (95% TATB, 5% Kel-F by weight) to obtain in-situ manganin pressure gauge data and run distances to detonation at various shock pressures. We report the behavior of the HMX-based explosive LX-04 that was damaged mechanically by applying a compressive load of 600 psi for 20,000 cycles, thus creating many small narrow cracks, or by cutting wedge shaped parts that were then loosely reassembled, thus creating a few large cracks. The thermally damaged LX-04 charges were heated to 190 C for long enough for the beta to delta solid - solid phase transition to occur, and then cooled to ambient temperature. Mechanically damaged LX-04 exhibited only slightly increased shock sensitivity, while thermally damaged LX-04 was much more shock sensitive. Similarly, the insensitive explosive PBX 9502 was mechanically damaged using the same two techniques. Since PBX 9502 does not undergo a solid - solid phase transition but does undergo irreversible or 'rachet' growth when thermally cycled, thermal damage to PBX 9502 was induced by this procedure. As for LX-04, the thermally damaged PBX 9502 demonstrated a greater shock sensitivity than mechanically damaged PBX 9502. The Ignition and Growth reactive flow model calculated the increased sensitivities by igniting more damaged LX-04 and PBX 9502 near the shock front based on the measured densities (porosities) of the damaged charges.

  6. Stellar Explosions: Hydrodynamics and Nucleosynthesis

    Science.gov (United States)

    José, Jordi

    2015-12-01

    Stars are the main factories of element production in the universe through a suite of complex and intertwined physical processes. Such stellar alchemy is driven by multiple nuclear interactions that through eons have transformed the pristine, metal-poor ashes leftover by the Big Bang into a cosmos with 100 distinct chemical species. The products of stellar nucleosynthesis frequently get mixed inside stars by convective transport or through hydrodynamic instabilities, and a fraction of them is eventually ejected into the interstellar medium, thus polluting the cosmos with gas and dust. The study of the physics of the stars and their role as nucleosynthesis factories owes much to cross-fertilization of different, somehow disconnected fields, ranging from observational astronomy, computational astrophysics, and cosmochemistry to experimental and theoretical nuclear physics. Few books have simultaneously addressed the multidisciplinary nature of this field in an engaging way suitable for students and young scientists. Providing the required multidisciplinary background in a coherent way has been the driving force for Stellar Explosions: Hydrodynamics and Nucleosynthesis. Written by a specialist in stellar astrophysics, this book presents a rigorous but accessible treatment of the physics of stellar explosions from a multidisciplinary perspective at the crossroads of computational astrophysics, observational astronomy, cosmochemistry, and nuclear physics. Basic concepts from all these different fields are applied to the study of classical and recurrent novae, type I and II supernovae, X-ray bursts and superbursts, and stellar mergers. The book shows how a multidisciplinary approach has been instrumental in our understanding of nucleosynthesis in stars, particularly during explosive events.

  7. Understanding Trends in Catalytic Activity: The Effect of Adsorbate-Adsorbate Interactions for CO Oxidation Over Transition Metals

    DEFF Research Database (Denmark)

    Grabow, Lars; Larsen, Britt Hvolbæk; Nørskov, Jens Kehlet

    2010-01-01

    Using high temperature CO oxidation as the example, trends in the reactivity of transition metals are discussed on the basis of density functional theory (DFT) calculations. Volcano type relations between the catalytic rate and adsorption energies of important intermediates are introduced...... and the effect of adsorbate-adsorbate interaction on the trends is discussed. We find that adsorbate-adsorbate interactions significantly increase the activity of strong binding metals (left side of the volcano) but the interactions do not change the relative activity of different metals and have a very small...... influence on the position of the top of the volcano, that is, on which metal is the best catalyst....

  8. The gas dynamics of explosions

    CERN Document Server

    Lee,\tJohn H S

    2016-01-01

    Explosions, and the non-steady shock propagation associated with them, continue to interest researchers working in different fields of physics and engineering (such as astrophysics and fusion). Based on the author's course in shock dynamics, this book describes the various analytical methods developed to determine non-steady shock propagation. These methods offer a simple alternative to the direct numerical integration of the Euler equations and offer a better insight into the physics of the problem. Professor Lee presents the subject systematically and in a style that is accessible to graduate students and researchers working in shock dynamics, combustion, high-speed aerodynamics, propulsion and related topics.

  9. Explosive demolition of activated concrete

    International Nuclear Information System (INIS)

    This paper describes the removal of a radiologically contaminated concrete pad. This pad was removed during 1979 by operating personnel under the direction of the Waste Management Program of EG and G Idaho, Inc. The concrete pad was the foundation for the Organic Moderated Reactor Experiment (OMRE) reactor vessel located at the Idaho National Engineering Laboratory (INEL). The pad consisted of a cylindrical concrete slab 15 ft in diameter, 2 ft thick, and reinforced with steel bar. It was poured directly onto basalt rocks approximately 20 ft below grade. The entire pad contained induced radioactivity and was therefore demolished, boxed, and buried rather than being decontaminated. The pad was demolished by explosive blasting

  10. Ultraviolet Resonant Raman Enhancements in the Detection of Explosives

    Energy Technology Data Exchange (ETDEWEB)

    Short Jr., Billy Joe [Naval Postgraduate School, Monterey, CA (United States)

    2009-06-01

    Raman-based spectroscopy is potentially militarily useful for standoff detection of high explosives. Normal (non-resonance) and resonance Raman spectroscopies are both light scattering techniques that use a laser to measure the vibrational spectrum of a sample. In resonance Raman, the laser is tuned to match the wavelength of a strong electronic absorbance in the molecule of interest, whereas, in normal Raman the laser is not tuned to any strong electronic absorbance bands. The selection of appropriate excitation wavelengths in resonance Raman can result in a dramatic increase in the Raman scattering efficiency of select band(s) associated with the electronic transition. Other than the excitation wavelength, however, resonance Raman is performed experimentally the same as normal Raman. In these studies, normal and resonance Raman spectral signatures of select solid high explosive (HE) samples and explosive precursors were collected at 785 nm, 244 nm and 229 nm. Solutions of PETN, TNT, and explosive precursors (DNT & PNT) in acetonitrile solvent as an internal Raman standard were quantitatively evaluated using ultraviolet resonance Raman (UVRR) microscopy and normal Raman spectroscopy as a function of power and select excitation wavelengths. Use of an internal standard allowed resonance enhancements to be estimated at 229 nm and 244 nm. Investigations demonstrated that UVRR provided ~2000-fold enhancement at 244 nm and ~800-fold improvement at 229 nm while PETN showed a maximum of ~25-fold at 244 nm and ~190-fold enhancement at 229 nm solely from resonance effects when compared to normal Raman measurements. In addition to the observed resonance enhancements, additional Raman signal enhancements are obtained with ultraviolet excitation (i.e., Raman scattering scales as !4 for measurements based on scattered photons). A model, based partly on the resonance Raman enhancement results for HE solutions, is presented for estimating Raman enhancements for solid HE samples.

  11. Detonation Propagation Characteristics of Superposition Explosive Materials

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    In order to investigate detonation propagation characteristics of different charge patterns,the detonation velocities of superposition strip-shaped charges made up of a detonating cord and explosives were measured by a detonation velocity measuring instrument under conditions of different ignition.The experimental results and theoretical analysis show that the maximum detonation propagation velocity depends on the explosive materials with the maximum velocity among all the explosive materials.Using detonating cord in a superposition charge can shorten detonation propagation time and improve the efficiency of explosive energy.The measurement method of detonation propagation velocity and experimental results are presented and investigated.

  12. High Explosives Research and Development (HERD) Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The purpose is to provide high explosive formulation, chemical analysis, safety and performance testing, processing, X-ray, quality control and loading support for...

  13. Analysis of TROI-13 Steam Explosion Experiment

    Directory of Open Access Journals (Sweden)

    Mitja Uršič

    2008-01-01

    Full Text Available The prediction of steam explosion inducing loads in nuclear power plants must be based on results of experimental research programmes and on simulations using validated fuel-coolant interaction codes. In this work, the TROI-13 steam explosion experiment was analysed with the fuel-coolant interaction MC3D computer code. The TROI-13 experiment is one of several experiments performed in the TROI research program and resulted in a spontaneous steam explosion using corium melt. First, the TROI-13 premixing simulations were performed to determine the initial conditions for the steam explosion simulations and to evaluate the melt droplets hydrodynamic fragmentation model. Next, a number of steam explosion simulations were performed, varying the steam explosion triggering position and the melt droplets mass participating in the steam explosion. The simulation results revealed that there is an important influence of the participating melt droplets mass on the calculated pressure loads, whereas the influence of the steam explosion triggering position on the steam explosion development was less expressive.

  14. Explosive Field Visualization Based on Image Fusion

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wen-yao; JIANG Ling-shuang

    2009-01-01

    m the composite sequence. Experimental results show that the new images integrate the advantages of sources, effectively improve the visualization, and disclose more information about explosive field.

  15. Effect of heavy metal cations on the fate of extracellular DNA adsorbed and bound on clay minerals.

    OpenAIRE

    Ascher J.; Ceccherini M.T.; Arfaioli P.; Borgogni F.; Pietramellara G.

    2011-01-01

    The presence of high-valent metal cations on clay mineral surfaces is hypothesised to induce conformational changes in the secondary and tertiary structure of the DNA molecule adsorbed and bound onto clays, defined as M-conformation, and its condensation. The hypothesis that these reversible phenomena could enhance the resistance of DNA to enzymatic degradation strongly encourages the studies on the effects of heavy metal contamination in clay rich soils on the fate of extracellular soil DNA ...

  16. Pulse radiolysis study of reaction of bull serum albumin electron adduct with oxygen. Polychromatic kinetics of reaction with adsorbed oxygen

    International Nuclear Information System (INIS)

    By the method of pulse radiolysis the reaction of bull serum albumin electron adduct with oxygen is investigated. As pulsed radiation source electron linear accelerators with particle energy of 8.0 and 4.5 MeV and pulse time of 40 ns and 2.2 μs, respectively have been used. It is assumed that the disappearance of protein electron adduct occurs in the course of its interaction with oxygen adsorbed on protein globular molecule

  17. Recoil ions from molecular targets: sequential Coulomb explosions

    International Nuclear Information System (INIS)

    Fast ion collision processes appear to be ideal for producing multiply charged molecular ions. The advantage of this technique has not been appreciated so far and very little work has been carried out so far. We have initiated a programme to study the formation of multiply charged molecular ions and their dissociation dynamics using fast ion beam from the pelletron. Measurements have been carried out on several molecules including N2, CO, CO2, CS2, CH4 and CH3I. Measurements of the kinetic energy distributions of the fragment ions provided novel results on the fragmentation of CS2 and CO2 ions. As expected the positive ions of S and O possessed very large kinetic energies resulting from the Coulomb explosion of highly charged molecular ions. The surprising result was that the positive ions (C+ and C2+) from the central carbon atom of the linear symmetric molecules possessed much larger energies that what is expected from the conventional physical picture of Coulomb explosion. It is concluded that the observed high kinetic energy C+ and C2+ ions are formed by sequential fragmentation of CO2n+ ions through an intermediate K-shell excited CO+* ions. (author). 4 refs., 1 fig

  18. 27 CFR 555.181 - Reporting of plastic explosives.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 3 2010-04-01 2010-04-01 false Reporting of plastic..., FIREARMS, AND EXPLOSIVES, DEPARTMENT OF JUSTICE EXPLOSIVES COMMERCE IN EXPLOSIVES Marking of Plastic Explosives § 555.181 Reporting of plastic explosives. All persons, other than an agency of the United...

  19. 30 CFR 75.1310 - Explosives and blasting equipment.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Explosives and blasting equipment. 75.1310... SAFETY AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1310 Explosives and blasting equipment. (a) Only permissible explosives, approved sheathed explosive units,...

  20. Turning things downside up: Adsorbate induced water flipping on Pt(111)

    International Nuclear Information System (INIS)

    We have examined the adsorption of the weakly bound species N2, O2, CO, and Kr on the (√(37)×√(37))R25.3∘ water monolayer on Pt(111) using a combination of molecular beam dosing, infrared reflection absorption spectroscopy, and temperature programmed desorption. In contrast to multilayer crystalline ice, the adsorbate-free water monolayer is characterized by a lack of dangling OH bonds protruding into the vacuum (H-up). Instead, the non-hydrogen-bonded OH groups are oriented downward (H-down) to maximize their interaction with the underlying Pt(111) substrate. Adsorption of Kr and O2 have little effect on the structure and vibrational spectrum of the “√(37)” water monolayer while adsorption of both N2, and CO are effective in “flipping” H-down water molecules into an H-up configuration. This “flipping” occurs readily upon adsorption at temperatures as low as 20 K and the water monolayer transforms back to the H-down, “√(37)” structure upon adsorbate desorption above 35 K, indicating small energy differences and barriers between the H-down and H-up configurations. The results suggest that converting water in the first layer from H-down to H-up is mediated by the electrostatic interactions between the water and the adsorbates

  1. Accelerator Analysis of Tributyltin Adsorbed onto the Surface of a Tributyltin Resistant Marine Pseudoalteromonas sp. Cell

    Directory of Open Access Journals (Sweden)

    Akira Kitamura

    2008-10-01

    Full Text Available Tributyltin (TBT released into seawater from ship hulls is a stable marine pollutant and obviously remains in marine environments. We isolated a TBT resistant marine Pseudoalteromonas sp. TBT1 from sediment of a ship’s ballast water. The isolate (109.3 ± 0.2 colony-forming units mL-1 adsorbed TBT in proportion to the concentrations of TBTCl externally added up to 3 mM, where the number of TBT adsorbed by a single cell was estimated to be 108.2. The value was reduced to about one-fifth when the lysozyme-treated cells were used. The surface of ethanol treated cells became rough, but the capacity of TBT adsorption was the same as that for native cells. These results indicate that the function of the cell surface, rather than that structure, plays an important role to the adsorption of TBT. The adsorption state of TBT seems to be multi-layer when the number of more than 106.8 TBT molecules is adsorbed by a single cell.

  2. Mass and Force Sensing of an Adsorbate on a Beam Resonator Sensor

    Directory of Open Access Journals (Sweden)

    Yin Zhang

    2015-06-01

    Full Text Available The mass sensing superiority of a micro-/nano-mechanical resonator sensor over conventional mass spectrometry has been, or at least is being firmly established. Because the sensing mechanism of a mechanical resonator sensor is the shifts of resonant frequencies, how to link the shifts of resonant frequencies with the material properties of an analyte formulates an inverse problem. Besides the analyte/adsorbate mass, many other factors, such as position and axial force, can also cause the shifts of resonant frequencies. The in situ measurement of the adsorbate position and axial force is extremely difficult if not impossible, especially when an adsorbate is as small as a molecule or an atom. Extra instruments are also required. In this study, an inverse problem of using three resonant frequencies to determine the mass, position and axial force is formulated and solved. The accuracy of the inverse problem solving method is demonstrated, and how the method can be used in the real application of a nanomechanical resonator is also discussed. Solving the inverse problem is helpful to the development and application of a mechanical resonator sensor for two reasons: reducing extra experimental equipment and achieving better mass sensing by considering more factors.

  3. Functionalized molecules studied by STM: motion, switching and reactivity

    International Nuclear Information System (INIS)

    Functionalized molecules represent the central issue of molecular nanotechnology. Scanning tunnelling microscopy (STM) is a powerful method to investigate such molecules, because it allows us to image them with sub-molecular resolution when adsorbed on a surface and can be used at the same time as a tool to manipulate single molecules in a controlled way. Such studies permit deep insight into the conformational, mechanical and electronic structure and thus functionalities of the molecules. In this review, recent experiments on specially designed molecules, acting as model systems for molecular nanotechnology, are reviewed. The presented studies focus on key functionalities: lateral rolling and hopping motion on a supporting surface, the switching behaviour of azobenzene derivatives by using the STM tip and the controlled reactivity of molecular side groups, which enable the formation of covalently bound molecular nanoarchitectures. (topical review)

  4. Chernobyl: Anatomy of the explosion

    International Nuclear Information System (INIS)

    On Friday, 26 April 1986, it was planned to shut down the fourth unit of the Chernobyl Atomic Power Station, U.S.S.R., for periodic maintenance. The procedure supplied the opportunity to perform a further experiment; operation of the turbine in free rotation regime, which occurs when the steam is cut down while the turbine is still running. It so happened that carrying out this experiment turned out to be the worst accident in the history of nuclear power industry. The first part of the article proceeds to a second by second detailed analysis of the causes of the catastrophe. The analysis uses official data and reports. The author covers the sequence of events, which led up to two explosions in the second hour of that tragic morning. In the second part of the article, the author provides hints and suggestions, so that 'the tragedy of Chernobyl does not become a useless lesson'. With regard to what, so far, has been published, the novelty of the article may be a diagram showing the excessive changes that affected the main parameters (power, water flow through circulating pumps, steam pressure in separators, and length of the immersed part of control rods) in the fourth unit during the last seconds before the explosion. If may be noteworthy to mention that the curves supplied here are based on data stored in the computer 'SCALA'. 2 figs

  5. Single bank NOx adsorber for heavy duty diesel engines

    NARCIS (Netherlands)

    Genderen, M. van; Aken, M.G. van

    2003-01-01

    In a NOx adsorber programme the feasibility for applying this technology to heavy duty diesel engines was investigated. After modelling and simulations for realising best λ < 1 engine conditions a platform was build which was used to obtain good NOx adsorber regeneration settings in a number of stea

  6. Selective sorption of perfluorooctane sulfonate on molecularly imprinted polymer adsorbents

    Institute of Scientific and Technical Information of China (English)

    Shubo DENG; Danmeng SHUAI; Qiang YU; Jun HUANG; Gang YU

    2009-01-01

    Perfluorooctane sulfonate (PFOS), as a potential persistent organic pollutant, has been widely detected in water environments, and has become a great concern in recent years. PFOS is very stable and difficult to decompose using conventional techniques. Sorption may be an attractive method to remove it from water. In this study, the molecularly imprinted polymer (MIP) adsorbents were prepared through the polymerization of 4-vinylpyridine under different preparation conditions in order to remove perfluorooctane sulfonate (PFOS) from water. The MIP adsorbents using perfluorooctanoic acid (PFOA) as the template had good imprinting effects and could selectively remove PFOS from aqueous solution. The sorption behaviors including sorption kinetics,isotherms, and effect of pH, salt, and competitive anions were investigated. Experimental results showed that the sorption of PFOS On the MIP adsorbents was very fast, pH-dependent, and highly selective. The achieved fast sorption equilibrium within 1 h was attributed to the surface sorption on the fine adsorbents. The sorption isotherms showed that the sorption selectivity of PFOS on the MIP adsorbents decreased at high PFOS concentrations, which may be due to the double-layer sorption and the formation of PFOS micelles on the sorbent surface. The sorption of PFOS on the MIP adsorbents was mainly dominated by the electrostatic interaction between the protonated vinylpyridine on the adsorbent surface and the anionic PFOS. The prepared MIP adsorbents can potentially be applied in water and wastewater treatment for selective removal of PFOS.

  7. The Condensation of Water on Adsorbed Viruses

    NARCIS (Netherlands)

    Alonso Carnicero, J.M.; Tatti, F.; Chuvilin, A.; Mam, K.; Ondarcuhu, T.; Bittner, A.M.

    2013-01-01

    The wetting and dewetting behavior of biological nanostructures and to a greater degree single molecules is not well-known even though their contact with water is the basis for all biology. Here, we show that environmental electron microscopy (EM) can be applied as a means of imaging the condensatio

  8. The origin of relative intensity fluctuations in single-molecule tip-enhanced Raman spectroscopy.

    Science.gov (United States)

    Sonntag, Matthew D; Chulhai, Dhabih; Seideman, Tamar; Jensen, Lasse; Van Duyne, Richard P

    2013-11-13

    An explanation of the relative intensity fluctuations observed in single-molecule Raman experiments is described utilizing both single-molecule tip-enhanced Raman spectroscopy and time-dependent density functional theory calculations. No correlation is observed in mode to mode intensity fluctuations indicating that the changes in mode intensities are completely independent. Theoretical calculations provide convincing evidence that the fluctuations are not the result of diffusion, orientation, or local electromagnetic field gradients but rather are the result of subtle variations of the excited-state lifetime, energy, and geometry of the molecule. These variations in the excited-state properties will provide information on adsorbate-adsorbate and adsorbate-substrate interactions and may allow for inversion of experimental results to obtain these excited-state properties.

  9. Cosmic Explosions in Three Dimensions

    Science.gov (United States)

    Höflich, Peter; Kumar, Pawan; Wheeler, J. Craig

    2004-12-01

    Introduction: 3-D Explosions: a meditation on rotation (and magnetic fields) J. C. Wheeler; Part I. Supernovae: Observations Today: 1. Supernova explosions: lessons from spectropolarimetry L. Wang; 2. Spectropolarimetric observations of Supernovae A. Filippenko and D. C. Leonard; 3. Observed and physical properties of type II plateau supernovae M. Hamuy; 4. SN1997B and the different types of Type Ic Supernovae A. Clocchiatti, B. Leibundgut, J. Spyromilio, S. Benetti, E. Cappelaro, M. Turatto and M. Phillips; 5. Near-infrared spectroscopy of stripped-envelope Supernovae C. L. Gerardy, R. A. Fesen, G. H. Marion, P. Hoeflich and J. C. Wheeler; 6. Morphology of Supernovae remnants R. Fesen; 7. The evolution of Supernova remnants in the winds of massive stars V. Dwarkadas; 8. Types for the galactic Supernovae B. E. Schaefer; Part II. Theory of Thermonuclear Supernovae: 9. Semi-steady burning evolutionary sequences for CAL 83 and CAL 87: supersoft X-ray binaries are Supernovae Ia progenitors S. Starrfield, F. X. Timmes, W. R. Hix, E. M. Sion, W. M. Sparks and S. Dwyer; 10. Type Ia Supernovae progenitors: effects of the spin-up of the white dwarfs S.-C. Yoon and N. Langer; 11. Terrestrial combustion: feedback to the stars E. S. Oran; 12. Non-spherical delayed detonations E. Livne; 13. Numerical simulations of Type Ia Supernovae: deflagrations and detonations V. N. Gamezo, A. M. Khokhlov and E. S. Oran; 14. Type Ia Supernovae: spectroscopic surprises D. Branch; 15. Aspherity effects in Supernovae P. Hoeflich, C. Gerardy and R. Quimby; 16. Broad light curve SneIa: asphericity or something else? A. Howell and P. Nugent; 17. Synthetic spectrum methods for 3-D SN models R. Thomas; 18. A hole in Ia' spectroscopic and polarimetric signatures of SN Ia asymmetry due to a companion star D. Kasen; 19. Hunting for the signatures of 3-D explosions with 1-D synthetic spectra E. Lentz, E. Baron and P. H. Hauschildt; 20. On the variation of the peak luminosity of Type Ia J. W. Truran, E

  10. Low Frequency Electromagnetic Pulse and Explosions

    Energy Technology Data Exchange (ETDEWEB)

    Sweeney, J J

    2011-02-01

    This paper reviews and summarizes prior work related to low frequency (< 100 Hz) EMP (ElectroMagnetic Pulse) observed from explosions. It focuses on how EMP signals might, or might not, be useful in monitoring underground nuclear tests, based on the limits of detection, and physical understanding of these signals. In summary: (1) Both chemical and nuclear explosions produce an EMP. (2) The amplitude of the EMP from underground explosions is at least two orders of magnitude lower than from above ground explosions and higher frequency components of the signal are rapidly attenuated due to ground conductivity. (3) In general, in the near field, that is distances (r) of less than 10s of kilometers from the source, the amplitude of the EMP decays approximately as 1/r{sup 3}, which practically limits EMP applications to very close (<{approx}1km) distances. (4) One computational model suggests that the EMP from a decoupled nuclear explosion may be enhanced over the fully coupled case. This has not been validated with laboratory or field data. (5) The magnitude of the EMP from an underground nuclear explosion is about two orders of magnitude larger than that from a chemical explosion, and has a larger component of higher frequencies. In principle these differences might be used to discriminate a nuclear from a chemical explosion using sensors at very close (<{approx}1 km) distances. (6) Arming and firing systems (e.g. detonators, exploding bridge wires) can also produce an EMP from any type of explosion. (7) To develop the understanding needed to apply low frequency EMP to nuclear explosion monitoring, it is recommended to carry out a series of controlled underground chemical explosions with a variety of sizes, emplacements (e.g. fully coupled and decoupled), and arming and firing systems.

  11. Close-in airblast from underground explosions

    International Nuclear Information System (INIS)

    Air overpressures as a function of time have been measured from surface zero to about 170 ft/lb1/3 along the ground from nuclear and chemical explosions. Charge depths varied from the surface to depths below which explosion gases are contained. A ground-shock-induced air pressure pulse is clearly distinguishable from the pulse caused by venting gases. Measured peak overpressures show reasonable agreement with the theoretical treatment by Monta. In a given medium the suppression of blast with explosion burial depth is a function of the relative distance at which the blast is observed. Rates of suppression of peak overpressure with charge burial are different for the two pulses. Rates are determined for each pulse over the range of distances at which measurements have been made of air overpressure from chemical explosions in several media. Nuclear data are available from too few shots for similar dependence on burial depth and distance to be developed, but it is clear that the gas venting peak overpressure from nuclear explosions is much more dependent on medium than that from chemical explosions. For above-ground explosions, experiment has shown that airblast from a I-kiloton nuclear explosion is equal to that from a 0.5-kiloton TNT explosion. Data on ground-shock-induced airblast is now sufficient to show that a similar relationship may exist for buried explosions. Because of medium dependence of the gas venting pulse from nuclear explosions, data from additional nuclear events will be required before a chemical/nuclear airblast equivalence can be determined for the gas-venting pulse. (author)

  12. Adsorption of Fluoride Ion by Inorganic Cerium Based Adsorbent

    Institute of Scientific and Technical Information of China (English)

    Jiao Zhongzhi(焦中志); Chen Zhonglin; Yang Min; Zhang Yu; Li Guibai

    2004-01-01

    Excess of fluoride in drinking water is harmful to human health, the concentration of F- ions must be maintained in the range of 0.5 to 1.5 mg/L. An inorganic cerium based adsorbent (CTA) is developed on the basis of research of adsorption of fluoride on cerium oxide hydrate. Some adsorption of fluoride by CTA adsorbent experiments were carried out, and results showed that CTA adsorbent has a quick adsorption speed and a large adsorption capacity. Adsorption follows Freundlich isotherm, and low pH value helps fluoride removal. Some physical-chemical characteristics of CTA adsorbent were experimented, fluoride removal mechanism was explored, and results showed that hydroxyl group of CTA adsorbent played an important role in the fluoride removal.

  13. Pulse radiolysis investigation of the reaction of the electronic adduct of bovine serum albumin with oxygen. Polychromatic kinetics of the reaction with adsorbed oxygen

    International Nuclear Information System (INIS)

    The method of pulse radiolysis was used to investigate the reaction of the electronic adduct of bovine serum albumin with oxygen. It was suggested that the disappearance of the electronic adduct of the protein occurs in the course of its interaction with oxygen adsorbed on the globular protein molecule

  14. Intermixed Adatom and Surface‐Bound Adsorbates in Regular Self‐Assembled Monolayers of Racemic 2‐Butanethiol on Au(111)

    DEFF Research Database (Denmark)

    Ouyang, Runhai; Yan, Jiawei; Jensen, Palle Skovhus;

    2015-01-01

    In situ scanning tunneling microscopy combined with density functional theory molecular dynamics simulations reveal a complex structure for the self‐assembled monolayer (SAM) of racemic 2‐butanethiol on Au(111) in aqueous solution. Six adsorbate molecules occupy a (10×√3)R30° cell organized as tw...

  15. Inhibition of Hotspot Formation in Polymer Bonded Explosives Using an Interface Matching Low Density Polymer Coating at the Polymer–Explosive Interface

    OpenAIRE

    An, Qi; Goddard, William A.; Zybin, Sergey V.; Luo, Sheng-Nian

    2014-01-01

    In order to elucidate how shocks in heterogeneous materials affect decomposition and reactive processes, we used the ReaxFF reactive force field in reactive molecules dynamics (RMD) simulations of the effects of strong shocks (2.5 and 3.5 km/s) on a prototype polymer bonded explosive (PBX) consisting of cyclotrimethylene trinitramine (RDX) bonded to hydroxyl-terminated polybutadiene (HTPB). We showed earlier that shock propagation from the high density RDX to the low density polymer (RDX → Po...

  16. Efficient adsorbents of nanoporous aluminosilicate monoliths for organic dyes from aqueous solution.

    Science.gov (United States)

    El-Safty, Sherif A; Shahat, Ahmed; Awual, Md Rabiul

    2011-07-01

    Growing public awareness on the potential risk to humans of toxic chemicals in the environment has generated demand for new and improved methods for toxicity assessment and removal, rational means for health risk estimation. With the aim of controlling nanoscale adsorbents for functionality in molecular sieving of organic pollutants, we fabricated cubic Im3m mesocages with uniform entrance and large cavity pores of aluminosilicates as highly promising candidates for the colorimetric monitoring of organic dyes in an aqueous solution. However, a feasible control over engineering of three-dimensional (3D) mesopore cage structures with uniform entrance (~5 nm) and large cavity (~10 nm) allowed the development of nanoadsorbent membranes as a powerful tool for large-quantity and high-speed (in minutes) adsorption/removal of bulk molecules such as organic dyes. Incorporation of high aluminum contents (Si/Al=1) into 3D cubic Im3m cage mesoporous silica monoliths resulted in small, easy-to-use optical adsorbent strips. In such adsorption systems, natural surfaces of active acid sites of aluminosilicate strips strongly induced both physical adsorption of chemically responsive dyes and intraparticle diffusion into cubic Im3m mesocage monoliths. Results likewise indicated that although aluminosilicate strips with low Si/Al ratios exhibit distortion in pore ordering and decrease in surface area and pore volume, enhancement of both molecular converges and intraparticle diffusion onto the network surfaces and into the pore architectures of adsorbent membranes was achieved. Moreover, 3D mesopore cage adsorbents are reversible, offering potential for multiple adsorption assays.

  17. Adlayer structure dependent ultrafast desorption dynamics in carbon monoxide adsorbed on Pd (111)

    Science.gov (United States)

    Hong, Sung-Young; Xu, Pan; Camillone, Nina R.; White, Michael G.; Camillone, Nicholas

    2016-07-01

    We report our ultrafast photoinduced desorption investigation of the coverage dependence of substrate-adsorbate energy transfer in carbon monoxide adlayers on the (111) surface of palladium. As the CO coverage is increased, the adsorption site population shifts from all threefold hollows (up to 0.33 ML), to bridge and near bridge (>0.5 to 0.6 ML) and finally to mixed threefold hollow plus top site (at saturation at 0.75 ML). We show that between 0.24 and 0.75 ML this progression of binding site motifs is accompanied by two remarkable features in the ultrafast photoinduced desorption of the adsorbates: (i) the desorption probability increases roughly two orders magnitude, and (ii) the adsorbate-substrate energy transfer rate observed in two-pulse correlation experiments varies nonmonotonically, having a minimum at intermediate coverages. Simulations using a phenomenological model to describe the adsorbate-substrate energy transfer in terms of frictional coupling indicate that these features are consistent with an adsorption-site dependent electron-mediated energy coupling strength, ηel, that decreases with binding site in the order: three-fold hollow > bridge and near bridge > top site. This weakening of ηel largely counterbalances the decrease in the desorption activation energy that accompanies this progression of adsorption site motifs, moderating what would otherwise be a rise of several orders of magnitude in the desorption probability. Within this framework, the observed energy transfer rate enhancement at saturation coverage is due to interadsorbate energy transfer from the copopulation of molecules bound in three-fold hollows to their top-site neighbors.

  18. Surface Chirality of Gly-Pro Dipeptide Adsorbed on a Cu(110) Surface.

    Science.gov (United States)

    Cruguel, Hervé; Méthivier, Christophe; Pradier, Claire-Marie; Humblot, Vincent

    2015-07-01

    The adsorption of chiral Gly-Pro dipeptide on Cu(110) has been characterized by combining in situ polarization modulation infrared reflection absorption spectroscopy (PM-RAIRS) and X-ray photoelectron spectroscopy (XPS). The chemical state of the dipeptide, and its anchoring points and adsorption geometry, were determined at various coverage values. Gly-Pro molecules are present on Cu(110) in their anionic form (NH2 /COO(-)) and adsorb under a 3-point binding via both oxygen atoms of the carboxylate group and via the nitrogen atom of the amine group. Low-energy electron diffraction (LEED) and scanning tunneling microscopy (STM) have shown the presence of an extended 2D chiral array, sustained via intermolecular H-bonds interactions. Furthermore, due to the particular shape of the molecule, only one homochiral domain is formed, creating thus a truly chiral surface. PMID:25847844

  19. NMR Studies of the Dynamics of HD Adsorbed on MCM-41

    Science.gov (United States)

    Huan, Chao; Hamida, Jaha; Sullivan, Neil

    We report the results of measurements of the nuclear spin-spin and spin-lattice relaxation times of a monolayer of HD molecules adsorbed on MCM-41 for temperatures 1 . 5 < T < 20 K. Two distinct characteristic relaxation times are observed. A slow diffusion process for 5 < T < 8 . 8 K and a faster rate with a distinctly different activation energy for 8 . 9 < T < 12 K. The behavior is fluid-like above 12 K. We discuss the results in terms of an expected cluster formation at low temperatures followed by the diffusion of single molecules at high temperatures. Work suported by the National Science Foundation - DMR-1303599 and DMR-1157490 (National High Magnetic Field Laboratory).

  20. Milestone Report - Complete New Adsorbent Materials for Marine Testing to Demonstrate 4.5 g-U/kg Adsorbent

    Energy Technology Data Exchange (ETDEWEB)

    Janke, Christopher James [ORNL; Das, Sadananda [ORNL; Oyola, Yatsandra [ORNL; Mayes, Richard T. [ORNL; Saito, Tomonori [ORNL; Brown, Suree [ORNL; Gill, Gary [PNNL; Kuo, Li-Jung [PNNL; Wood, Jordana [PNNL

    2014-08-01

    This report describes work on the successful completion of Milestone M2FT-14OR03100115 (8/20/2014) entitled, “Complete new adsorbent materials for marine testing to demonstrate 4.5 g-U/kg adsorbent”. This effort is part of the Seawater Uranium Recovery Program, sponsored by the U.S. Department of Energy, Office of Nuclear Energy, and involved the development of new adsorbent materials at the Oak Ridge National Laboratory (ORNL) and marine testing at the Pacific Northwest National Laboratory (PNNL). ORNL has recently developed two new families of fiber adsorbents that have demonstrated uranium adsorption capacities greater than 4.5 g-U/kg adsorbent after marine testing at PNNL. One adsorbent was synthesized by radiation-induced graft polymerization of itaconic acid and acrylonitrile onto high surface area polyethylene fibers followed by amidoximation and base conditioning. This fiber showed a capacity of 4.6 g-U/kg adsorbent in marine testing at PNNL. The second adsorbent was prepared by atom-transfer radical polymerization of t-butyl acrylate and acrylonitrile onto halide-functionalized round fibers followed by amidoximation and base hydrolysis. This fiber demonstrated uranium adsorption capacity of 5.4 g-U/kg adsorbent in marine testing at PNNL.

  1. Summary of European directives for explosion safety

    NARCIS (Netherlands)

    Versloot, N.H.A.; Klein, A.J.J.; Maaijer, M. de

    2008-01-01

    On July 1, 2003 a transitional period has ended and two European directives became fully active: • Directive 1999/92/EC • Directive 94/9/EC These directives have an impact on companies with an explosion hazard (gas, vapor, mist, or dust explosions) and on manufacturers of equipment intended to be us

  2. Splitting PMMA with Mini Cutting Explosives

    Institute of Scientific and Technical Information of China (English)

    LI Zhiqiang; LIU Xiaomin; XIAO Yin; ZHAO Yonggang; ZHAO Longmao

    2006-01-01

    In order to improve the present aviation ejection escape system,the application of explosion cutting technique to aviation escape system is proposed to weaken the strength of canopy before ejecting it.A series of mini cutting explosives are designed to investigate the process of splitting PMMA plate.The phenomenon of spallation in PMMA is observed.The effects of different parameters of mini cutting explosives on the cutting depth are obtained.Consequently the appropriate material of half-circular metal covers,explosive types and the ranges of charge quantities are determined.On the other hand,the cutting process of aviation PMMA plate by mini cutting explosives is simulated by means of nonlinear dynamic analysis code LS-DYNA.In finite element analysis,Arbitrary Lagrangian Euler (ALE) algorithm is used to depict the fluid property of high energy explosives.Continuous damage material model is used to simulate the complicate dynamic damage behavior of PMMA due to explosion shock waves.Only sliding contact option is defined to fulfill the fluid-structure interaction between explosives and PMMA plate by distributed parameter methods.Phenomenon of spallation observed in the experiment is presented in the simulation.The relationship between the penetration depth of PMMA plate and charge linear density obtained by numerical simulation agrees well with experimental result.

  3. Fire and explosion hazards of oil shale

    Energy Technology Data Exchange (ETDEWEB)

    1989-01-01

    The US Bureau of Mines publication presents the results of investigations into the fire and explosion hazards of oil shale rocks and dust. Three areas have been examined: the explosibility and ignitability of oil shale dust clouds, the fire hazards of oil shale dust layers on hot surfaces, and the ignitability and extinguishment of oil shale rubble piles. 10 refs., 54 figs., 29 tabs.

  4. 76 FR 8923 - Explosive Siting Requirements

    Science.gov (United States)

    2011-02-16

    ... ``explosive hazard facility'' as a facility at a launch site where solid propellant, liquid propellant, or... would no longer refer to the solid explosives governed by this section as solid propellants because, technically, the provision applies to more than just solid propellants. Currently, Sec. 420.65 states that...

  5. Glass produced by underground nuclear explosions

    International Nuclear Information System (INIS)

    Detonation of an underground nuclear explosive produces a strong shock wave which propagates spherically outward, vaporizing the explosive and nearby rock and melting, the surrounding rock. The vaporized material expands adiabatically, forming a cavity. As the energy is dissipated during the cavity formation process, the explosive and rock debris condense and mix with the melted rock. The melt flows to the bottom of the cavity where it is quenched by fractured rock fragments falling from above as the cavity collapses. Measurements indicate that about 740 tonnes of rock and/or soil are melted for every kiloton (1012 calories) of explosive energy, or about 25% of the explosive energy goes to melting rock. The resulting glass composition reflects the composition of the unaltered rock with explosive debris. The appearance ranges from white pumice to dense, dark lava. The bulk composition and color vary with the amount of explosive iron incorporated into the glass. The refractory explosion products are mixed with the solidified melt, although the degree of mixing is variable. Electron microprobe studies of glasses produced by Rainier in welded tuff have produced the following results: glasses are dehydrated relative to the host media, glasses are extremely heterogeneous on a 20 μm scale, a ubiquitous feature is the presence of dark marble-cake regions in the glass, which were locally enriched in iron and may be related to the debris, optically amorphous regions provide evidence of shock melting, only limited major element redistribution and homogenization occur within the cavity

  6. Some analytical methods for explosives: Part 2

    Energy Technology Data Exchange (ETDEWEB)

    Selig, W.

    1965-12-08

    This report is the second compilation of methods for analyzing explosives. All the methods were developed for routine performance by techniques, and an attempt has therefore been made to keep them as simple as possible. Methods are presented for analyzing plastic-bonded explosives based on sym-cyclomethylenetetra-nitramine (HMX), based on viton in addition to HMX, and based on pentraerythritol tetranitrate (PETN).

  7. 49 CFR 173.59 - Description of terms for explosives.

    Science.gov (United States)

    2010-10-01

    .... Substances consisting of a deflagrating liquid explosive, used for propulsion. Propellant, solid. Substances consisting of a deflagrating solid explosive, used for propulsion. Propellants. Deflagrating explosives used... equipment quickly. Rocket motors. Articles consisting of a solid, liquid, or hypergolic propellant...

  8. Morphomechanical Innovation Drives Explosive Seed Dispersal.

    Science.gov (United States)

    Hofhuis, Hugo; Moulton, Derek; Lessinnes, Thomas; Routier-Kierzkowska, Anne-Lise; Bomphrey, Richard J; Mosca, Gabriella; Reinhardt, Hagen; Sarchet, Penny; Gan, Xiangchao; Tsiantis, Miltos; Ventikos, Yiannis; Walker, Simon; Goriely, Alain; Smith, Richard; Hay, Angela

    2016-06-30

    How mechanical and biological processes are coordinated across cells, tissues, and organs to produce complex traits is a key question in biology. Cardamine hirsuta, a relative of Arabidopsis thaliana, uses an explosive mechanism to disperse its seeds. We show that this trait evolved through morphomechanical innovations at different spatial scales. At the organ scale, tension within the fruit wall generates the elastic energy required for explosion. This tension is produced by differential contraction of fruit wall tissues through an active mechanism involving turgor pressure, cell geometry, and wall properties of the epidermis. Explosive release of this tension is controlled at the cellular scale by asymmetric lignin deposition within endocarp b cells-a striking pattern that is strictly associated with explosive pod shatter across the Brassicaceae plant family. By bridging these different scales, we present an integrated mechanism for explosive seed dispersal that links evolutionary novelty with complex trait innovation. VIDEO ABSTRACT.

  9. Hydrodynamics of Explosion Experiments and Models

    CERN Document Server

    Kedrinskii, Valery K

    2005-01-01

    Hydronamics of Explosion presents the research results for the problems of underwater explosions and contains a detailed analysis of the structure and the parameters of the wave fields generated by explosions of cord and spiral charges, a description of the formation mechanisms for a wide range of cumulative flows at underwater explosions near the free surface, and the relevant mathematical models. Shock-wave transformation in bubbly liquids, shock-wave amplification due to collision and focusing, and the formation of bubble detonation waves in reactive bubbly liquids are studied in detail. Particular emphasis is placed on the investigation of wave processes in cavitating liquids, which incorporates the concepts of the strength of real liquids containing natural microinhomogeneities, the relaxation of tensile stress, and the cavitation fracture of a liquid as the inversion of its two-phase state under impulsive (explosive) loading. The problems are classed among essentially nonlinear processes that occur unde...

  10. First-principles study of SF6 decomposed gas adsorbed on Au-decorated graphene

    Science.gov (United States)

    Zhang, Xiaoxing; Yu, Lei; Gui, Yingang; Hu, Weihua

    2016-03-01

    We theoretically investigated the decomposed gaseous components of sulfur hexafluoride (SF6), namely, H2S, SO2, SOF2, and SO2F2, adsorbed on pristine and Au-embedded graphene based on the revised Perdew-Burke-Ernzerhof calculation, which empirically includes a dispersion correction (DFT-D) for van der Waals interaction with standard generalized gradient approximation. Pristine graphene exhibits weak adsorption and absence of charge transfer, which indicates barely satisfactory sensing for decomposed components. The Au atom introduces magnetism to the pristine graphene after metal-embedded decoration as well as enhances conductivity. All four molecules induce certain hybridization between the molecules and Au-graphene, which results in chemical interactions. SOF2 and SO2F2 exhibit a strong chemisorption interaction with Au-graphene, while H2S and SO2 exhibit quasi-molecular binding effects. Only H2S exhibits n-type doping to Au-graphene, whereas the rest gases exhibit p-type doping. Magnetic moments fluctuate substantially in the original Au-graphene when H2S and SO2 are adsorbed. While the adsorption effects of SOF2 and SO2F2 generate magnetism quenching. The charge transfer mechanism is also discussed in this paper. These results will shed light on the valuable application of Au-embedded graphene for selective gas sensing and spintronics.

  11. Imaging atoms and molecules on surfaces by scanning tunnelling microscopy

    International Nuclear Information System (INIS)

    This review discusses nearly 30 years of scanning tunnelling microscopy (STM) work on high resolution imaging of numerous materials systems, giving a historical perspective on the field through the author's work. After a brief discussion of early STM and atomic force microscope (AFM) instrumentation development, the review discusses high resolution STM imaging on semiconductors, metals on semiconductors, Au(1 1 1), metal on metals including surface alloys, oxygen on metals, molecules adsorbed on metals, and AFM measurements of friction on graphite and mica.

  12. Ionospheric effects of supernova explosions

    Science.gov (United States)

    Edwards, P. J.

    Possible ionospheric effects of supernova explosions are considered, with special attention given to those of SN 1987a. Results are presented on the calculations of anticipated X-ray/UV flare parameters, including the shock temperature, the minimum flare duration, the average photon energy, and the shock-front travel time for a range of stellar radii bracketing SK 202-69, which was identified by White Malin (1987) as the progenitor star for SN 1987a. It is shown that the characteristics of the X-ray/UV flare are strongly influenced by the radius of the shock wave breakout, so that the flare from SN 1987a can be anticipated to have characteristics intermediate between those attributed to compact stars and stars with extended envelopes.

  13. Mass extinctions and supernova explosions

    CERN Document Server

    Korschinek, Gunther

    2016-01-01

    A nearby supernova (SN) explosion could have negatively influenced life on Earth, maybe even been responsible for mass extinctions. Mass extinction poses a significant extinction of numerous species on Earth, as recorded in the paleontologic, paleoclimatic, and geological record of our planet. Depending on the distance between the Sun and the SN, different types of threats have to be considered, such as ozone depletion on Earth, causing increased exposure to the Sun's ultraviolet radiation, or the direct exposure of lethal x-rays. Another indirect effect is cloud formation, induced by cosmic rays in the atmosphere which result in a drop in the Earth's temperature, causing major glaciations of the Earth. The discovery of highly intensive gamma ray bursts (GRBs), which could be connected to SNe, initiated further discussions on possible life-threatening events in Earth's history. The probability that GRBs hit the Earth is very low. Nevertheless, a past interaction of Earth with GRBs and/or SNe cannot be exclude...

  14. Mercury adsorption properties of sulfur-impregnated adsorbents

    Science.gov (United States)

    Hsi, N.-C.; Rood, M.J.; Rostam-Abadi, M.; Chen, S.; Chang, R.

    2002-01-01

    Carbonaceous and noncarbonaceous adsorbents were impregnated with elemental sulfur to evaluate the chemical and physical properties of the adsorbents and their equilibrium mercury adsorption capacities. Simulated coal combustion flue gas conditions were used to determine the equilibrium adsorption capacities for Hg0 and HgCl2 gases to better understand how to remove mercury from gas streams generated by coal-fired utility power plants. Sulfur was deposited onto the adsorbents by monolayer surface deposition or volume pore filling. Sulfur impregnation increased the total sulfur content and decreased the total and micropore surface areas and pore volumes for all of the adsorbents tested. Adsorbents with sufficient amounts of active adsorption sites and sufficient microporous structure had mercury adsorption capacities up to 4,509 ??g Hg/g adsorbent. Elemental sulfur, organic sulfur, and sulfate were formed on the adsorbents during sulfur impregnation. Correlations were established with R2>0.92 between the equilibrium Hg0/HgCl2 adsorption capacities and the mass concentrations of elemental and organic sulfur. This result indicates that elemental and organic sulfur are important active adsorption sites for Hg0 and HgCl2.

  15. Methane Recovery from Gaseous Mixtures Using Carbonaceous Adsorbents

    Science.gov (United States)

    Buczek, Bronisław

    2016-06-01

    Methane recovery from gaseous mixtures has both economical and ecological aspect. Methane from different waste gases like mine gases, nitrogenated natural gases and biogases can be treated as local source for production electric and heat energy. Also occurs the problem of atmosphere pollution with methane that shows over 20 times more harmful environmental effect in comparison to carbon dioxide. One of the ways utilisation such gases is enrichment of methane in the PSA technique, which requires appropriate adsorbents. Active carbons and carbon molecular sieve produced by industry and obtained in laboratory scale were examined as adsorbent for methane recuperation. Porous structure of adsorbents was investigated using densimetry measurements and adsorption of argon at 77.5K. On the basis of adsorption data, the Dubinin-Radushkevich equation parameters, micropore volume (Wo) and characteristics of energy adsorption (Eo) as well as area micropores (Smi) and BET area (SBET) were determined. The usability of adsorbents in enrichment of the methane was evaluated in the test, which simulate the basic stages of PSA process: a) adsorbent degassing, b) pressure raise in column by feed gas, c) cocurrent desorption with analysis of out flowing gas. The composition of gas phase was accepted as the criterion of the suitability of adsorbent for methane separation from gaseous mixtures. The relationship between methane recovery from gas mixture and texture parameters of adsorbents was found.

  16. 27 CFR 555.109 - Identification of explosive materials.

    Science.gov (United States)

    2010-04-01

    ... Business or Operations § 555.109 Identification of explosive materials. (a) General. Explosive materials... in the English language, using Roman letters and Arabic numerals. (3) Licensed manufacturers...

  17. STM Simulation of Molecules on Ultrathin Insulating Overlayers Using Tight-Binding: Au-Pentacene on NaCl bilayer on Cu

    OpenAIRE

    Korventausta, Antti; Paavilainen, Sami; Niemi, Eeva; Nieminen, Jouko

    2008-01-01

    We present a fast and efficient tight-binding (TB) method for simulating scanning tunneling microscopy (STM) imaging of adsorbate molecules on ultrathin insulating films. Due to the electronic decoupling of the molecule from the metal surface caused by the presence of the insulating overlayer, the STM images of the frontier molecular orbitals can be simulated using a very efficient scheme, which also enables the analysis of phase shifts in the STM current. Au-pentacene complex adsorbed on a N...

  18. ADSORPTION OF PHENYLACETIC ACID ON MACROPOROUS POLYMERIC ADSORBENTS

    Institute of Scientific and Technical Information of China (English)

    PANBingcai; CHENJinlong; 等

    2002-01-01

    Several macroporous polymeric adsorbents(NDA-999,XAD-8,X-5 and XAD-2)were emplyed in the study to adsorb phenylacetic acid from aqueous solution.Effect of salt and ambient temperature on adsorption was studied using NDA-999 adsorbent and the adsorption process conforms to Freundlich′s model reasonably.Adsorption dynamics were conducted in batch experiments in order to make clear the mechanism of adsorption process.It is proved that the squared driving force mass transfer model can be adopted to elucidate the process.The treatment process of industrial wastewater containing high strength of phenylacetic acid was proposed for cleaner production of phenylacetic acid.

  19. ADSORPTION OF PHENYLACETIC ACID ON MACROPOROUS POLYMERIC ADSORBENTS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Several macroporous polymeric adsorbents (NDA-999, XAD-8, X-5 and XAD-2) wereemployed in the study to adsorb phenylacetic acid from aqueous solution. Effect of salt and ambienttemperature on adsorption was studied using NDA-999 adsorbent and the adsorption processconforms to Freundlich's model reasonably. Adsorption dynamics were conducted in batchexperiments in order to make clear the mechanism of adsorption process. It is proved that thesquared driving force mass transfer model can be adopted to elucidate the process. The treatmentprocess of industrial wastewater containing high strength of phenylacetic acid was proposed forcleaner production of phenylacetic acid.

  20. The Electrochemical Properties of Thionine Adsorbed Monolayer on Gold Electrode

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A gold electrode modified with adsorbed thionine monolayer was investigated with ac impedance and cyclic voltammetry method. It was found therewere some different redox properties for the adsorbed thionine depended on the different potential scanning rate. At the slower potential scanning rate (10 mV@s-1), the dimer of thionine appeared and possessed the catalytic activity for the oxidation of ascorbic acid.The underpotential deposition (UPD) and the bulk deposition of Cu2+ were also employed to investigate the monolayer of adsorbed thionine.

  1. Adsorption and oxidation of formaldehyde on a polycrystalline Pt film electrode: An in situ IR spectroscopy search for adsorbed reaction intermediates

    Directory of Open Access Journals (Sweden)

    Zenonas Jusys

    2014-05-01

    Full Text Available As part of a mechanistic study of the electrooxidation of C1 molecules we have systematically investigated the dissociative adsorption/oxidation of formaldehyde on a polycrystalline Pt film electrode under experimental conditions optimizing the chance for detecting weakly adsorbed reaction intermediates. Employing in situ IR spectroscopy in an attenuated total reflection configuration (ATR-FTIRS with p-polarized IR radiation to further improve the signal-to-noise ratio, and using low reaction temperatures (3 °C and deuterium substitution to slow down the reaction kinetics and to stabilize weakly adsorbed reaction intermediates, we could detect an IR absorption band at 1660 cm−1 characteristic for adsorbed formyl intermediates. This assignment is supported by an isotope shift in wave number. Effects of temperature, potential and deuterium substitution on the formation and disappearance of different adsorbed species (COad, adsorbed formate, adsorbed formyl, are monitored and quantified. Consequences on the mechanism for dissociative adsorption and oxidation of formaldehyde are discussed.

  2. Fast Chromatographic Method for Explosive Profiling

    Directory of Open Access Journals (Sweden)

    Pierre-Hugues Stefanuto

    2015-05-01

    Full Text Available Security control is becoming a major global issue in strategic locations, such as airports, official buildings, and transit stations. The agencies responsible for public security need powerful and sensitive tools to detect warfare agents and explosives. Volatile signature detection is one of the fastest and easiest ways to achieve this task. However, explosive chemicals have low volatility making their detection challenging. In this research, we developed and evaluated fast chromatographic methods to improve the characterization of volatile signatures from explosives samples. The headspace of explosives was sampled with solid phase micro-extraction fiber (SPME. Following this step, classical gas chromatography (GC and comprehensive two-dimensional GC (GC×GC were used for analysis. A fast GC approach allows the elution temperature of each analyte to be decreased, resulting in decreased thermal degradation of sensitive compounds (e.g., nitro explosives. Using fast GC×GC, the limit of detection is further decreased based on the cryo-focusing effect of the modulator. Sampling of explosives and chromatographic separation were optimized, and the methods then applied to commercial explosives samples. Implementation of fast GC methods will be valuable in the future for defense and security forensics applications.

  3. Pixelated diffraction signatures for explosive detection

    Science.gov (United States)

    O'Flynn, Daniel; Reid, Caroline; Christodoulou, Christiana; Wilson, Matt; Veale, Matthew C.; Seller, Paul; Speller, Robert

    2012-06-01

    Energy dispersive X-ray diffraction (EDXRD) is a technique which can be used to improve the detection and characterisation of explosive materials. This study has performed EDXRD measurements of various explosive compounds using a novel, X-ray sensitive, pixelated, energy resolving detector developed at the Rutherford Appleton Laboratory, UK (RAL). EDXRD measurements are normally performed at a fixed scattering angle, but the 80×80 pixel detector makes it possible to collect both spatially resolved and energy resolved data simultaneously. The detector material used is Cadmium Telluride (CdTe), which can be utilised at room temperature and gives excellent spectral resolution. The setup uses characteristics from both energy dispersive and angular dispersive scattering techniques to optimise specificity and speed. The purpose of the study is to develop X-ray pattern "footprints" of explosive materials based on spatial and energy resolved diffraction data, which can then be used for the identification of such materials hidden inside packages or baggage. The RAL detector is the first energy resolving pixelated detector capable of providing an energy resolution of 1.0-1.5% at energies up to 150 keV. The benefit of using this device in a baggage scanner would be the provision of highly specific signatures to a range of explosive materials. We have measured diffraction profiles of five explosives and other compounds used to make explosive materials. High resolution spectra have been obtained. Results are presented to show the specificity of the technique in finding explosives within baggage.

  4. Adherence of platelets to in situ albumin-binding surfaces under flow conditions: role of surface-adsorbed albumin

    International Nuclear Information System (INIS)

    Surfaces that preferentially bind human serum albumin (HSA) were generated by grafting albumin-binding linear peptide (LP1) onto silicon surfaces. The research aim was to evaluate the adsorption pattern of proteins and the adhesion of platelets from platelet-poor plasma and platelet-rich plasma, respectively, by albumin-binding surfaces under physiological shear rate (96 and 319 s−1) conditions. Bound proteins were quantified using enzyme-linked immunosorbent assays (ELISAs) and two-dimensional gel electrophoresis. A ratio of ∼1000:100:1 of adsorbed HSA, human immunoglobulin (HIgG) and human fibrinogen (HFib) was noted, respectively, on LP1-functionalized surfaces, and a ratio of ∼5:2:1 of the same was noted on control surfaces, as confirmed by ELISAs. The surface-adsorbed von Willebrand factor was undetectable by sensitive ELISAs. The amount of adhered platelets correlated with the ratio of adsorbed HSA/HFib. Platelet morphology was more rounded on LP1-functionalized surfaces when compared to control surfaces. The platelet adhesion response on albumin-binding surfaces can be explained by the reduction in the co-adsorption of other plasma proteins in a surface environment where there is an excess of albumin molecules, coupled with restrictions in the conformational transitions of other surface-adsorbed proteins into hemostatically active forms. (paper)

  5. Toward 3D graphene oxide gels based adsorbents for high-efficient water treatment via the promotion of biopolymers.

    Science.gov (United States)

    Cheng, Chong Sage; Deng, Jie; Lei, Bei; He, Ai; Zhang, Xiang; Ma, Lang; Li, Shuang; Zhao, Changsheng

    2013-12-15

    Recent studies showed that graphene oxide (GO) presented high adsorption capacities to various water contaminants. However, the needed centrifugation after adsorption and the potential biological toxicity of GO restricted its applications in wastewater treatment. In this study, a facile method is provided by using biopolymers to mediate and synthesize 3D GO based gels. The obtained hybrid gels present well-defined and interconnected 3D porous network, which allows the adsorbate molecules to diffuse easily into the adsorbent. The adsorption experiments indicate that the obtained porous GO-biopolymer gels can efficiently remove cationic dyes and heavy metal ions from wastewater. Methylene blue (MB) and methyl violet (MV), two cationic dyes, are chosen as model adsorbates to investigate the adsorption capability and desorption ratio; meanwhile, the influence of contacting time, initial concentration, and pH value on the adsorption capacity of the prepared GO-biopolymer gels are also studied. The GO-biopolymer gels displayed an adsorption capacity as high as 1100 mg/g for MB dye and 1350 mg/g for MV dye, respectively. Furthermore, the adsorption kinetics and isotherms of the MB were studied in details. The experimental data of MB adsorption fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm, and the results indicated that the adsorption process was controlled by the intraparticle diffusion. Moreover, the adsorption data revealed that the porous GO-biopolymer gels showed good selective adsorbability to cationic dyes and metal ions.

  6. Effects of the surface chemistry of macroreticular adsorbents on the adsorption of 1-naphthol/1-naphthylamine mixtures from water

    Institute of Scientific and Technical Information of China (English)

    ZHANG Wei-ming; CHEN Jin-long; CHEN Qun; HE Min-yang; PAN Bing-cai; ZHANG Quan-xing

    2005-01-01

    The adsorption behaviors of 1-naphthol, 1-naphthylamine and 1-naphthol/1-naphthylamine mixtures in water over two macroreticular adsorbents were investigated in single or binary batch systems at 293 K, 303 K and 313 K respectively. All the adsorption isotherms in the studied systems can be adequately fitted by Langmuir model. In the case of aminated macroreticular adsorbent NDA103,1-naphthol is adsorbed to a larger extent than 1-naphthylamine; while, the opposite trend is found for nonpolar macroreticular adsorbent NDA100. It is noteworthy that at higher temperature(303 K and 313 K), the total uptake amounts of 1-naphthol and 1-naphthylamine in all binary-component systems are obvious larger than the pure uptake amounts in single-component systems, which is presumably due to the cooperative effect primarily arisen from the hydrogen-bonding interaction between the loaded 1-naphthol and 1-naphthylamine molecules.The simultaneous adsorption systems were confirmed to be helpful to the selective adsorption towards 1-naphthol according to the larger selective index.

  7. Dynamics of CO 2 Adsorption on Amine Adsorbents. 2. Insights Into Adsorbent Design

    KAUST Repository

    Bollini, Praveen

    2012-11-21

    Packed bed breakthrough experiments are reported for commercial zeolite 13X and 3-aminopropyl-functionalized SBA-15 silica materials with three different amine loadings. Mass and heat transfer dynamics for all four materials are modeled successfully. Amine adsorbents with open pores are found to exhibit faster mass diffusion rates compared to zeolite 13X. When amine loading is increased by coupling aminopropyl groups, premature breakthrough combined with a long tail is observed. Contrary to conventional physisorbants, finite heat losses to the column wall do not explain the long breakthrough tail. A rate model that accounts for heterogeneity in diffusion was found to accurately capture the breakthrough shape of the high loading material. Batch uptake measurements support the hypothesis that slow diffusion through the polymer phase is what hampers adsorption kinetics in the high amine loading adsorbent. The results emphasize the importance of designing materials that are not overloaded with amine sites, as excessive amine loadings can lead to depressed adsorption kinetics and premature column breakthrough. © 2012 American Chemical Society.

  8. On the Violence of High Explosive Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Tarver, C M; Chidester, S K

    2004-02-09

    High explosive reactions can be caused by three general energy deposition processes: impact ignition by frictional and/or shear heating; bulk thermal heating; and shock compression. The violence of the subsequent reaction varies from benign slow combustion to catastrophic detonation of the entire charge. The degree of violence depends on many variables, including the rate of energy delivery, the physical and chemical properties of the explosive, and the strength of the confinement surrounding the explosive charge. The current state of experimental and computer modeling research on the violence of impact, thermal, and shock-induced reactions is reviewed.

  9. Techniques of industrial radiology in military explosives

    International Nuclear Information System (INIS)

    The use of industrial radiology techniques id very important for military explosive fabrication. The cylindrical-ogive bodies made in forged metal have their interior fulfilled with high melted explosive and they must explode when they reach the target. The granades, as these bodies are called, are thrown by cannons and their interior are submitted to high pressures and accelerations which can cause a premature detonation, in most case, in interior of tube, in case of they have defects in explosive mass. The origins of defects, its localization and classification presenting the techniques used and disposable in Brazil are discussed. (M.C.K.)

  10. Study on Property of Desensitized Explosive Film

    Institute of Scientific and Technical Information of China (English)

    李国新; 王晓丽; 焦清介; 刘淑珍

    2004-01-01

    The mechanical sensitivity, the critical thickness of detonation wave propagation and detonation velocity of desensitized PETN film were studied by experiments. The relationship between the mass of desensitizer paraffin wax and the friction sensitivity of desensitized PETN film was tested. According to the microstructure of film, the function of desensitizer was explained. It was proved that the explosive film could make explosive element micromation and kept its inherence properties by the result of testing the propagating critical dimension of the desensitized PETN film detonation wave. The explosive velocity of confined desensitized PETN film was tested by the multiplex optical fibre.

  11. Explosive Detection and Identification by PGNAA

    Energy Technology Data Exchange (ETDEWEB)

    E.H. Seabury; A.J. Caffrey

    2004-11-01

    The goal of this project was to determine the feasibility of using field-portable prompt gamma-ray neutron activation analysis (PGNAA) to detect and identify explosives in improvised nuclear devices (INDs). The studies were carried out using the Monte Carlo N-Particle (MCNP) code developed at Los Alamos National Laboratory. The model results were tested experimentally using explosive simulants and the PINS PGNAA system developed at Idaho National Engineering and Environmental Laboratory (INEEL). The results of the MCNP calculations and PINS measurements are presented in this report. The calculations and measurements were in good agreement and indicate that most explosives are readily distinguishable from one another.

  12. Explosive Detection and Identification by PGNAA

    International Nuclear Information System (INIS)

    The goal of this project was to determine the feasibility of using field-portable prompt gamma-ray neutron activation analysis (PGNAA) to detect and identify explosives in improvised nuclear devices (INDs). The studies were carried out using the Monte Carlo N-Particle (MCNP) code developed at Los Alamos National Laboratory. The model results were tested experimentally using explosive simulants and the PINS PGNAA system developed at Idaho National Engineering and Environmental Laboratory (INEEL). The results of the MCNP calculations and PINS measurements are presented in this report. The calculations and measurements were in good agreement and indicate that most explosives are readily distinguishable from one another

  13. Water waves generated by underwater explosion

    CERN Document Server

    Mehaute, Bernard Le

    1996-01-01

    This is the first book on explosion-generated water waves. It presents the theoretical foundations and experimental results of the generation and propagation of impulsively generated waves resulting from underwater explosions. Many of the theories and concepts presented herein are applicable to other types of water waves, in particular, tsunamis and waves generated by the fall of a meteorite. Linear and nonlinear theories, as well as experimental calibrations, are presented for cases of deep and shallow water explosions. Propagation of transient waves on dissipative, nonuniform bathymetries to

  14. Explosives detection: a challenge for physical chemistry.

    Science.gov (United States)

    Steinfeld, J I; Wormhoudt, J

    1998-01-01

    The detection of explosives, energetic materials, and their associated compounds for security screening, demining, detection of unexploded ordnance, and pollution monitoring is an active area of research. A wide variety of detection methods and an even wider range of physical chemistry issues are involved in this very challenging area. This review focuses on techniques such as optical and mass spectrometry and chromatography for detection of trace amounts of explosives with short response times. We also review techniques for detecting the decomposition fragments of these materials. Molecular data for explosive compounds are reviewed where available. PMID:15012428

  15. Mechanism of formation of humus coatings on mineral surfaces 3. Composition of adsorbed organic acids from compost leachate on alumina by solid-state 13C NMR

    Science.gov (United States)

    Wershaw, R. L.; Llaguno, E.C.; Leenheer, J.A.

    1996-01-01

    The adsorption of compost leachate DOC on alumina is used as a model for elucidation of the mechanism of formation of natural organic coatings on hydrous metal oxide surfaces in soils and sediments. Compost leachate DOC is composed mainly of organic acid molecules. The solid-state 13C NMR spectra of these organic acids indicate that they are very similar in composition to aquatic humic substances. Changes in the solid-state 13C NMR spectra of compost leachate DOC fractions adsorbed on alumina indicate that the DOC molecules are most likely adsorbed on metal oxide surfaces through a combination of polar and hydrophobic interaction mechanisms. This combination of polar and hydrophobic mechanism leads to the formation of bilayer coatings of the leachate molecules on the oxide surfaces.

  16. Radiation grafted adsorbents for newly emerging environmental applications

    Science.gov (United States)

    Mahmoud Nasef, Mohamed; Ting, T. M.; Abbasi, Ali; Layeghi-moghaddam, Alireza; Sara Alinezhad, S.; Hashim, Kamaruddin

    2016-01-01

    Radiation induced grafting (RIG) is acquired to prepare a number of adsorbents for newly emerging environmental applications using a single route involving RIG of glycidymethacrylate (GMA) onto polyethylene-polypropylene (PE-PP) non-woven fabric. The grafted fabric was subjected to one of three functionalization reactions to impart desired ionic characters. This included treatment with (1) N-dimethyl-D-glucamine, (2) triethylamine and (3) triethylamine and alkalisation with KOH. Fourier transform infrared spectroscopy (FTIR) and scanning electron microscope (SEM) were used to study the changes in chemical and physical structures of the obtained fibrous adsorbents. The potential applications of the three adsorbents for removal of boron from solutions, capturing CO2 from CO2/N2 mixtures and catalysing transesterification of triacetin/methanol to methyl acetate (biodiesel) were explored. The obtained fibrous adsorbents provide potential alternatives to granular resins for the investigated applications and require further development.

  17. A NOVEL METAL CHELATE AFFINITY ADSORBENT FOR PROTEIN UPTAKE

    Institute of Scientific and Technical Information of China (English)

    WANGYongjian; BAIShu; 等

    2001-01-01

    In this article,a spherical chitosan gel crosslinked by epichlorohydrin was prepared.It was then loaded with copper ions to produce a metal chelate affinity adsorbent for protein.The uptake of bovine serum albumin(BSA)by the affinity adsorbent was investigated.and the adsorption capacity for BSA as high as 40mg/g-wet beads was observed.The adsorption equilibrium data was well correlated by the Langmuir equation.The adsorption was considerably affected by pH.In additio.The amount of BSA adsorbed onto the beads decreased with the increasing of aqueous phase ionic strength,so adsorbed BAS can be desorbed by adjusting pH orionic strength of the solution.

  18. Adsorption of remazol brilliant blue on an orange peel adsorbent

    Directory of Open Access Journals (Sweden)

    M. R. Mafra

    2013-09-01

    Full Text Available A novel orange peel adsorbent developed from an agricultural waste material was characterised and utilised for the removal of Remazol Brilliant Blue from an artificial textile-dye effluent. The adsorption thermodynamics of this dye-adsorbent pair was studied in a series of equilibrium experiments. The time to reach equilibrium was 15 h for the concentration range of 30 mg L-1 to 250 mg L-1. The adsorption capacity decreased with increasing temperature, from 9.7 mg L-1 at 20 ºC to 5.0 mg L-1 at 60 ºC. Both the Langmuir and Freundlich isotherm models fitted the adsorption data quite reasonably. The thermodynamic analysis of dye adsorption onto the orange peel adsorbent indicated its endothermic and spontaneous nature. Thus, the application of orange peel adsorbent for the removal of dye from a synthetic textile effluent was successfully demonstrated.

  19. TESTING OF CARBONACEOUS ADSORBENTS FOR REMOVAL OF POLLUTANTS FROM WATER

    Directory of Open Access Journals (Sweden)

    RAISA NASTAS

    2012-03-01

    Full Text Available Testing of carbonaceous adsorbents for removal of pollutants from water. Relevant direction for improving of quality of potable water is application of active carbons at various stages of water treatments. This work includes complex research dealing with testing of a broad spectrum of carbonaceous adsorbents for removal of hydrogen sulfide and nitrite ions from water. The role of the surface functional groups of carbonaceous adsorbents, their acid-basic properties, and the influence of the type of impregnated heteroatom (N, O, or metals (Fe, Cu, Ni, on removal of hydrogen sulfide species and nitrite ions have been researched. The efficiency of the catalyst obtained from peach stones by impregnation with Cu2+ ions of oxidized active carbon was established, being recommended for practical purposes to remove the hydrogen sulfide species from the sulfurous ground waters. Comparative analysis of carbonaceous adsorbents reveals the importance of surface chemistry for oxidation of nitrite ions.

  20. Low Pressure Adsorbent for Recovery & Storage Vented Hydrogen Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A high performance fullerene-based adsorbent is proposed for recovery and storage hydrogen and separating helium via pressure-swing-adsorption (PSA) process....

  1. Sol-Gel Synthesized Adsorbents for Metal Separation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A series of organo-ceramic adsorbents have been synthesized by a sol-gel processing technique for metal ion extraction. These adsorbents generally have significantly high metal uptake capacities, good physical-chemical stabilities, and well-designed pore geometries compared to other pre-existing metalchelating ceramic-based adsorbents. This work describes the synthesis and evaluation of pyrazole and calix[4]arene crown adsorbents for selective separation of platinum, palladium, and gold and cesium ions,respectively, from solutions. These materials exhibit mesoporous properties with high surface areas and pore volumes. The sol-gel synthesis starting with precursor silanes and titania results in gel particles of desired pore characteristics and high capacity and stability. Characterization studies, such as adsorption isotherms, breakthrough curves for fixed bed operation, and material stability, show promising results for applications to metal sepation.

  2. Development of novel adsorbents for environmental cleaning by radiation

    International Nuclear Information System (INIS)

    In order to improve our amenity spaces, the demand of non-odorous atmosphere is needed. Toxic gases such as trimethylamine and ammonia have been treated as the pollutant of the atmosphere. The development of an excellent and effective adsorbent for the toxic gases has been performed here and there all over the world. However, the development of the adsorbent with the consideration for conservation of environment must be made as one of the requisites. Therefore, we proposed the use of radiation for the preparation of toxic-gas-adsorbing materials. On the other hand, in our daily life, the large amount of calcium and magnesium contained in our drinking water has hindered the removal of a trace amount of pollutant such as lead. As a result, the development of the metal-ion-adsorbing material is very indispensable indeed. (J.P.N.)

  3. The structure of deuterated benzene films adsorbed on the graphite (0001) basal plane: what happens below and above the monolayer coverage?

    OpenAIRE

    Bahn, Emanuel; Hedgeland, Holly; Jardine, Andrew P.; Henry, Paul F.; Hansen, Thomas C.; Fouquet, Peter

    2014-01-01

    An exact description of the interactions in aromatic carbon systems is a key condition for the design of carbon based nanomaterials. In this paper we investigate the binding and adsorbate structure of the simplest prototype system in this class – the single aromatic ring molecule benzene on graphite. We have collected neutron diffraction data of the ordered phase of deuterated benzene, C6D6, adsorbed on the graphite (0001) basal plane surface. We examined relative coverages from 0.15 up to 1....

  4. Formation of Ultracold Molecules

    Energy Technology Data Exchange (ETDEWEB)

    Cote, Robin [Univ. of Connecticut, Storrs, CT (United States)

    2016-01-28

    Advances in our ability to slow down and cool atoms and molecules to ultracold temperatures have paved the way to a revolution in basic research on molecules. Ultracold molecules are sensitive of very weak interactions, even when separated by large distances, which allow studies of the effect of those interactions on the behavior of molecules. In this program, we have explored ways to form ultracold molecules starting from pairs of atoms that have already reached the ultracold regime. We devised methods that enhance the efficiency of ultracold molecule production, for example by tuning external magnetic fields and using appropriate laser excitations. We also investigates the properties of those ultracold molecules, especially their de-excitation into stable molecules. We studied the possibility of creating new classes of ultra-long range molecules, named macrodimers, thousand times more extended than regular molecules. Again, such objects are possible because ultra low temperatures prevent their breakup by collision. Finally, we carried out calculations on how chemical reactions are affected and modified at ultracold temperatures. Normally, reactions become less effective as the temperature decreases, but at ultracold temperatures, they can become very effective. We studied this counter-intuitive behavior for benchmark chemical reactions involving molecular hydrogen.

  5. Development of solid adsorbent materials for CO₂capture

    OpenAIRE

    Ogbuka, Chidi Premie

    2013-01-01

    The application of solid adsorbents for gas separation in pre-combustion carbon capture from gasification processes has gained attention in recent times. This is due to the potential of the technology to reduce the overall energy penalty associated with the capture process. However, this requires the development of solid adsorbent materials with large selectivity, large adsorption capacity, fast adsorption kinetics for CO2 coupled with good mechanical strength and thermal stability. In this ...

  6. Plant waste materials from restaurants as the adsorbents for dyes

    OpenAIRE

    Pavlović Marija D.; Nikolić Ivan R.; Milutinović Milica D.; Dimitrijević-Branković Suzana I.; Šiler-Marinković Slavica S.; Antonović Dušan G.

    2015-01-01

    This paper has demonstrated the valorization of inexpensive and readily available restaurant waste containing most consumed food and beverage residues as adsorbents for methylene blue dye. Coffee, tea, lettuce and citrus waste have been utilized without any pre-treatment, thus the adsorption capacities and dye removal efficiency were determined. Coffee waste showed highest adsorbent capacity, followed by tea, lettuce and citrus waste. The dye removal was mo...

  7. THE USE OF LOW COST ADSORBENTS FOR PURIFICATION WASTEWATER

    OpenAIRE

    Višekruna, Antonija; Štrkalj, Anita; Marinić Pajc, Ljiljana

    2011-01-01

    Adsorption is one of the effective methods of advanced wastewater treatment, which industries employ to reduce hazardous organic and inorganic wastes in effluents. The use of low cost adsorbent has been investigated as a replacement for current costly methods of removing toxic substances from wastewater. In this article, the use of low cost adsorbents for the removal of toxic substances from wastewater has been reviewed.

  8. Residence time determination for adsorbent beds of different configurations

    Energy Technology Data Exchange (ETDEWEB)

    Otermat, J.E.; Wikoff, W.O.; Kovach, J.L.

    1995-02-01

    The residence time calculations of ASME AG-1 Code, Section FC, currently specify a screen surface area method, that is technically incorrect. Test data has been obtained on Type II adsorber trays of different configurations to establish residence time in the adsorber trays. These data indicate that the air volume/carbon volume ratio or the average screen area are more appropriate for the calculation of the residence time calculation than the currently used, smallest screen area basis.

  9. Partitioning model of the adsorption of explosives from soils to determine its environmental fate

    Directory of Open Access Journals (Sweden)

    Rosalina González Forero

    2014-12-01

    Full Text Available The purpose of this research was to identify the principal soil characteristics that influence the adsorption of munitions constituents (MC of explosives in soils, through a partitioning model to determine the fate of the explosives. To do that, batch experiments near 1:1 (w/v soil to solution ratios reflecting field conditions were conducted using a mixture of HMX, RDX, nitroglycerine (NG, nitroguanidine (NQ, TNT and 2,4-dinitrotoluene as MC, where the mix of MC was adsorbed in twenty-five different soils that varied from 4.0 to 43.2 % clay content and 0.07 to 18.23 % total carbon, in an experiment that involved 2 days of adsorption followed by four consecutive desorption steps. The most important result was that for each MC, even if it was in a mixture, were successfully predicted the partition coefficients using the organic carbon, cation exchange capacity and extractable iron as the principal soil characteristics that determine the fate of these explosives.

  10. Removal of chlorophenols in aqueous solution by carbon black low-cost adsorbents. Equilibrium study and influence of operation conditions

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez-Vargas, Joaquin R.; Navarro-Rodriguez, Juan A.; Beltran de Heredia, Jesus [Department of Chemical Engineering and Physical Chemistry, Area of Chemical Engineering, Faculty of Sciences, University of Extremadura, Avda. de Elvas, s/n, E-06071 Badajoz (Spain); Cuerda-Correa, Eduardo M., E-mail: emcc@unex.es [Department of Organic and Inorganic Chemistry, Faculty of Sciences, University of Extremadura, Avda. de Elvas, s/n, E-06071 Badajoz (Spain)

    2009-09-30

    The adsorption process of chlorophenols (CPs) by low-cost adsorbents such as carbon blacks has been studied. The influence of different parameters such as temperature, pH, ionic strength and textural properties of the adsorbents on the adsorption process of pentachlorophenol has been analyzed. The adsorption process is exothermal and parameters such as pH and ionic strength exert a noticeable influence on the adsorption capacity of the solute. These parameters influence the adsorption capacity in an opposite manner. Thus an increase in pH seems to unfavor the adsorption process, whereas the adsorption capacity increases with increasing ionic strength. In order to analyze the influence of the number of chlorine atoms in the molecule of solute the adsorption process of different chlorophenols (i.e., 4-chlorophenol, 3,5-dichlorophenol, 2,4,6-trichlorophenol and 2,3,4,6-tetrachlorophenol) was analyzed. As the number of chlorine atoms (and thus the volume of the molecule) increases, the penetration of the solute through the porous texture of the adsorbent is difficult and, consequently, the adsorption capacity decreases.

  11. Efforts to Consolidate Chalcogels with Adsorbed Iodine

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Brian J.; Pierce, David A.; Chun, Jaehun

    2013-08-28

    This document discusses ongoing work with non-oxide aerogels, called chalcogels, that are under development at the Pacific Northwest National Laboratory as sorbents for gaseous iodine. Work was conducted in fiscal year 2012 to demonstrate the feasibility of converting Sn2S3 chalcogel without iodine into a glass. This current document summarizes the work conducted in fiscal year 2013 to assess the consolidation potential of non-oxide aerogels with adsorbed iodine. The Sn2S3 and Sb13.5Sn5S20 chalcogels were selected for study. The first step in the process for these experiments was to load them with iodine (I2). The I2 uptake was ~68 mass% for Sn2S3 and ~50 mass% for Sb13.5Sn5S20 chalcogels. X-ray diffraction (XRD) of both sets of sorbents showed that metal-iodide complexes were formed during adsorption, i.e., SnI4 for Sn2S3 and SbI3 for Sb13.5Sn5S20. Additionally, metal-sulfide-iodide complexes were formed, i.e., SnSI for Sn2S3 and SbSI for Sb13.5Sn5S20. No XRD evidence for unreacted iodine was found in any of these samples. Once the chalcogels had reached maximum adsorption, the consolidation potential was assessed. Here, the sorbents were heated for consolidation in vacuum-sealed quartz vessels. The Sb13.5Sn5S20 chalcogel was heated both (1) in a glassy carbon crucible within a fused quartz tube and (2) in a single-containment fused quartz tube. The Sn2S3 chalcogel was only heated in a single-containment fused quartz tube. In both cases with the single-containment fused quartz experiments, the material consolidated nicely. However, in both cases, there were small fractions of metal iodides not incorporated into the final product as well as fused quartz particles within the melt due to the sample attacking the quartz wall during the heat treatment. The Sb13.5Sn5S20 did not appear to attack the glassy carbon crucible so, for future experiments, it would be ideal to apply a coating, such as pyrolytic graphite, to the inner walls of the fused quartz vessel to prevent

  12. Evaluation of a cesium adsorbent grafted with ammonium 12-molybdophosphate

    Science.gov (United States)

    Shibata, Takuya; Seko, Noriaki; Amada, Haruyo; Kasai, Noboru; Saiki, Seiichi; Hoshina, Hiroyuki; Ueki, Yuji

    2016-02-01

    A fibrous cesium (Cs) adsorbent was developed using radiation-induced graft polymerization with a cross-linked structure containing a highly stable adsorption ligand. The ligand, ammonium 12-molybdophosphate (AMP), was successfully introduced onto the fibrous polyethylene trunk material. The resulting Cs adsorbent contained 36% nonwoven fabric polyethylene (NFPE), 1% AMP, 2% triallyl isocyanurate (TAIC) and 61% glycidyl methacrylate (GMA). The adsorbent's Cs adsorption capacity was evaluated using batch and column tests. It was determined that the adsorbent could be used in a wide pH range. The amount of desorbed molybdenum, which can be used as an estimate for AMP stability on the Cs adsorbent, was minimized at the standard drinking water pH range of 5.8-8.6. Based from the inspection on the adherence of these results to the requirements set forth by the Food Sanitation Act by a third party organization, it can be concluded that the developed Cs adsorbent can be safely utilized for drinking water.

  13. Optimizing Conditions to Cholesterol Adsorbed with Carboxymethyl Chitosan

    Directory of Open Access Journals (Sweden)

    Mardiyah Kurniasih

    2016-05-01

    Full Text Available A research on optimizing conditions to cholesterol adsorbed have been performed. Optimization was performed by varying: contact time, adsorbent weight and temperature of the system's. A full factorial experimental design was used in this study. Characterization performed on the synthesized chitosan and carboxymethyl chitosan including FTIR, water content, ash content, solubility, porosity, and swelling effect. The results showed that carboxymethyl chitosan able to adsorb cholesterol under conditions optimal adsorbent with cholesterol ratio (1:200 with a contact time of 90 minutes at temperature of 40 °C. Meanwhile, at a temperature of 55 °C carboxymethyl chitosan capable of adsorb cholesterol under conditions optimal adsorbent with cholesterol ratio (1:300 with a contact time of 30 minutes. Chitosan and carboxymethyl chitosan synthesized has a water content of 7.4 and 10.2%, ash content of 0.14 and 2.29%, solubility in distilled water at 1.10-5and 1.98.10-3%, solubility in acetic acid 0.02 and 0.04%, porosity at 88.3% and 88.8%, and swelling at 163.13 and 182.98%.

  14. Cryogenic adsorber design in a helium refrigeration system

    Science.gov (United States)

    Hu, Zhongjun; Zhang, Ning; Li, Zhengyu; Li, Q.

    2012-06-01

    The cryogenic adsorber is specially designed to eliminate impurities in gaseous helium such as O2, and N2 which is normally difficult to remove, based on the reversible cryotrapping of impurities on an activated carbon bed. The coconut shell activated carbon is adopted because of its developed micropore structure and specific surface area. This activated carbon adsorption is mostly determined by the micropore structure, and the adsorption rate of impurities is inversely proportional to the square of the particle sizes. The active carbon absorber's maximum permissible flow velocity is 0.25 m/s. When the gas flow velocity increases, the adsorption diffusion rate of the adsorbent is reduced, because an increase in the magnitude of the velocity resulted in a reduced amount of heat transfer to a unit volume of impure gas. According to the numerical simulation of N2 adsorption dynamics, the appropriate void tower link speed and the saturated adsorption capacity are determined. Then the diameter and height of the adsorber are designed. The mass transfer length should be taken into account in the adsorber height design. The pressure decrease is also calculated. The important factors that influence the adsorber pressure decrease are the void tower speed, the adsorbed layer height, and the active carbon particle shape and size.

  15. Activity of lactoperoxidase when adsorbed on protein layers.

    Science.gov (United States)

    Haberska, Karolina; Svensson, Olof; Shleev, Sergey; Lindh, Liselott; Arnebrant, Thomas; Ruzgas, Tautgirdas

    2008-09-15

    Lactoperoxidase (LPO) is an enzyme, which is used as an antimicrobial agent in a number of applications, e.g., food technology. In the majority of applications LPO is added to a homogeneous product phase or immobilised on product surface. In the latter case, however, the measurements of LPO activity are seldom reported. In this paper we have assessed LPO enzymatic activity on bare and protein modified gold surfaces by means of electrochemistry. It was found that LPO rapidly adsorbs to bare gold surfaces resulting in an amount of LPO adsorbed of 2.9mg/m(2). A lower amount of adsorbed LPO is obtained if the gold surface is exposed to bovine serum albumin, bovine or human mucin prior to LPO adsorption. The enzymatic activity of the adsorbed enzyme is in general preserved at the experimental conditions and varies only moderately when comparing bare gold and gold surface pretreated with the selected proteins. The measurement of LPO specific activity, however, indicate that it is about 1.5 times higher if LPO is adsorbed on gold surfaces containing a small amount of preadsorbed mucin in comparison to the LPO directly adsorbed on bare gold.

  16. Three dimensional alignment of molecules using elliptically polarized laser fields

    DEFF Research Database (Denmark)

    Larsen, J.J.; Bjerre, N.; Hald, K.;

    2000-01-01

    We demonstrate, theoretically and experimentally, that an intense, elliptically polarized, nonresonant laser field can simultaneously force all three axes of a molecule to align along given axes fixed in space, thus inhibiting the free rotation in all three Euler angles. Theoretically, the effect...... is illustrated through time dependent quantum mechanical calculations. Experimentally, 3, 4-dibromothiophene molecules are aligned with a nanosecond laser pulse. The alignment is probed by 2D ion imaging of the fragments from a 20 fs laser pulse induced Coulomb explosion....

  17. Stereochemical configuration and selective excitation of the chiral molecule halothane

    CERN Document Server

    Pitzer, Martin; Burzynski, Phillip; Weller, Miriam; Metz, Daniel; Neff, Jonathan; Waitz, Markus; Trinter, Florian; Schmidt, Lothar Ph H; Williams, Joshua B; Jahnke, Till; Schmidt-Böcking, Horst; Berger, Robert; Dörner, Reinhard; Schöffler, Markus

    2016-01-01

    X-ray single-photon ionization and fragmentation of the chiral molecule halothane (CHBrClCF${}_{3}$) from a racemic mixture have been investigated using the COLTRIMS (Cold Target Recoil Ion Momentum Spectroscopy) technique. Two important facets related to the core ionization of this species are examined: Firstly, the distinction of enantiomers (mirror isomers) and the determination of absolute configuration on a single-molecule level by four-body Coulomb explosion; secondly, the interplay of site-selective excitation and fragmentation patterns. These results are easily transferrable to other molecular species and show the wealth of features

  18. Supernova neutrinos and explosive nucleosynthesis

    Energy Technology Data Exchange (ETDEWEB)

    Kajino, T. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588, Japan and Department of Astronomy, Graduate School of Science, The University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033 (Japan); Aoki, W. [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Cheoun, M.-K. [Department of Physics, Soongsil University, Seoul 156-743 (Korea, Republic of); Hayakawa, T. [Japan Atomic Energy Agency, Shirakara-Shirane 2-4, Tokai-mura, Ibaraki 319-1195 (Japan); Hidaka, J.; Hirai, Y.; Shibagaki, S. [National Astronomical Observatory, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Mathews, G. J. [Center for Astrophysics, Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Nakamura, K. [Faculty of Science and Engineering, Waseda University, Ohkubo 3-4-1, Shinjuku, Tokyo 169-8555 (Japan); Suzuki, T. [Department of Physics, College of Humanities and Sciences, Nihon University, Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550 (Japan)

    2014-05-09

    Core-collapse supernovae eject huge amount of flux of energetic neutrinos. We studied the explosive nucleosyn-thesis in supernovae and found that several isotopes {sup 7}Li, {sup 11}B, {sup 92}Nb, {sup 138}La and {sup 180}Ta as well as r-process nuclei are affected by the neutrino interactions. The abundance of these isotopes therefore depends strongly on the neutrino flavor oscillation due to the Mikheyev-Smirnov-Wolfenstein (MSW) effect. We discuss first how to determine the neutrino temperatures in order to explain the observed solar system abundances of these isotopes, combined with Galactic chemical evolution of the light nuclei and the heavy r-process elements. We then study the effects of neutrino oscillation on their abundances, and propose a novel method to determine the still unknown neutrino oscillation parameters, mass hierarchy and θ{sub 13}, simultaneously. There is recent evidence that SiC X grains from the Murchison meteorite may contain supernova-produced light elements {sup 11}B and {sup 7}Li encapsulated in the presolar grains. Combining the recent experimental constraints on θ{sub 13}, we show that our method sug-gests at a marginal preference for an inverted neutrino mass hierarchy. Finally, we discuss supernova relic neutrinos that may indicate the softness of the equation of state (EoS) of nuclear matter as well as adiabatic conditions of the neutrino oscillation.

  19. Laser initiated endotracheal tube explosion.

    Science.gov (United States)

    De Vane, G G

    1990-06-01

    A 62-year-old male with a diagnosis of subglottic and tracheal stenosis resulting from a prolonged intubation was scheduled for a laser bronchoscopy and placement of a silicon T-shaped tube. His history was significant for two myocardial infarctions, an episode of congestive heart failure and exertional angina. A 6 mm polyvinyl chloride endotracheal tube, wrapped with aluminum tape, was placed in an existing tracheostomy stoma. During the course of the procedure, a sudden bright flash occurred followed by an explosive noise and black smoke rising in the anesthesia circuit and from the patient's mouth. The endotracheal tube was removed and the patient was treated for first and second degree burns in the supraglottic area and base of the tongue. In laser surgery of the airway, special care should be given to reducing the flammability of the inspired gases which can be best accomplished by the mixture of helium with oxygen. Helium acts to retard ignition of polyvinyl chloride tubes in concentrations of 60% or greater. The external surface of the tube can also be protected with the application of a metallic tape affixed in a spiral fashion. Finally, a protocol for the management and treatment of this emergency should be adopted and rehearsed. PMID:2378234

  20. Asymmetric Explosions of Thermonuclear Supernovae

    CERN Document Server

    Ghezzi, C R; Horváth, J E

    2004-01-01

    A type Ia supernova explosion starts in a white dwarf as a laminar deflagration at the center of the star and soon several hydrodynamic instabilities (in particular, the Rayleigh-Taylor (R-T) instability) begin to act. In previous work (Ghezzi, de Gouveia Dal Pino, & Horvath 2001), we addressed the propagation of an initially laminar thermonuclear flame in presence of a magnetic field assumed to be dipolar. We were able to show that, within the framework of a fractal model for the flame velocity, the front is affected by the field through the quenching of the R-T instability growth in the direction perpendicular to the field lines. As a consequence, an asymmetry develops between the magnetic polar and the equatorial axis that gives a prolate shape to the burning front. We have here computed numerically the total integrated asymmetry as the flame front propagates outward through the expanding shells of decreasing density of the magnetized white dwarf progenitor, for several chemical compositions, and found...

  1. Glossary on peaceful nuclear explosions terms

    International Nuclear Information System (INIS)

    The report presents a glossary of terms in the area of peaceful nuclear explosions. The terms are in English, French, Russian and Spanish with cross-references for the corresponding terms of the other languages

  2. Pretreatment of Corn Stalk by Steam Explosion

    Institute of Scientific and Technical Information of China (English)

    邵自强; 田永生; 谭惠民

    2003-01-01

    A steam explosion pretreatment, which is one of the best ways of pretreating plant stalk, is applied at various severities to corn stalk. It could effectively modify the super-molecular structure of corn stalk and defibrating corn stalk into individual components. The relationship between yield of reducing sugar and the operating conditions, including temperature, pressure of steam explosion pretreatment and acidity, is also established. Experimental results prove that the steam explosion substantially increases the yield of reducing sugar, and the optimal condition for steam explosion is as follows: the pressure is 2.0 MPa, the pressure-retaining time 300 s, the initial acid concentration 1% and the acid treatment time 24 h.

  3. Isolator fragmentation and explosive initiation tests

    Energy Technology Data Exchange (ETDEWEB)

    Dickson, Peter [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Rae, Philip John [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Foley, Timothy J. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Novak, Alan M. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Armstrong, Christopher Lee [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Baca, Eva V. [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States); Gunderson, Jake Alfred [Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

    2015-09-30

    Three tests were conducted to evaluate the effects of firing an isolator in proximity to a barrier or explosive charge. The tests with explosive were conducted without barrier, on the basis that since any barrier will reduce the shock transmitted to the explosive, bare explosive represents the worst-case from an inadvertent initiation perspective. No reaction was observed. The shock caused by the impact of a representative plastic material on both bare and cased PBX9501 is calculated in the worst-case, 1-D limit, and the known shock response of the HE is used to estimate minimum run-to-detonation lengths. The estimates demonstrate that even 1-D impacts would not be of concern and that, accordingly, the divergent shocks due to isolator fragment impact are of no concern as initiating stimuli.

  4. Magnetorotational Explosive Instability in Keplerian Disks

    CERN Document Server

    Shtemler, Yuri; Mond, Michael

    2015-01-01

    In this paper it is shown that deferentially rotating disks that are in the presence of weak axial magnetic field are prone to a new nonlinear explosive instability. The latter occurs due to the near-resonance three-wave interactions of a magnetorotational instability with stable Alfven-Coriolis and magnetosonic modes. The dynamical equations that govern the temporal evolution of the amplitudes of the three interacting modes are derived. Numerical solutions of the dynamical equations indicate that small frequency mismatch gives rise to two types of behavior: 1. explosive instability which leads to infinite values of the three amplitudes within a finite time, and 2. bounded irregular oscillations of all three amplitudes. Asymptotic solutions of the dynamical equations are obtained for the explosive instability regimes and are shown to match the numerical solutions near the explosion time.

  5. Corona-discharge-initiated mine explosions

    Energy Technology Data Exchange (ETDEWEB)

    Sacks, H.K.; Novak, T. [Virginia Polytechnic Institute & State University, Blacksburg, VA (United States). Dept. of Mining & Minerals Engineering

    2005-10-01

    Strong circumstantial evidence suggests that lightning has initiated methane explosions in abandoned and sealed areas of underground coal mines. The Mine Safety and Health Administration (MSHA) investigated several of these occurrences within recent years. The investigated explosions occurred at significant depths, ranging from 700 to 1200 ft. Data from the National Lightning Detection Network indicated a strong correlation between the times and locations of the explosions with those of specific lightning strikes. This paper proposes that corona discharge from a steel borehole casing is the most likely mechanism responsible for these ignitions. A recently investigated mine explosion and fire at a depth greater than 1000 ft was selected for this study. Computer simulations were performed, using data collected at the mine site. CDEGS software from Safe Engineering Services & Technologies, Ltd. and MaxwellSV from Ansoft Corporation were used for the simulations.

  6. Optical chemosensors and reagents to detect explosives

    OpenAIRE

    Salinas Soler, Yolanda; Martínez Mañez, Ramón; Marcos Martínez, María Dolores; Sancenón Galarza, Félix; Costero Nieto, Ana Maria; PARRA ALVAREZ, MARGARITA; GIL GRAU, SALVADOR

    2012-01-01

    This critical review is focused on examples reported from 1947 to 2010 related to the design of chromo-fluorogenic chemosensors and reagents for explosives (141 references). © 2012 The Royal Society of Chemistry.

  7. Rabbit lung injury induced by explosive decompression

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective: To study the mechanism of rabbit lunginjury caused by explosive decompression. Methods: A total of 42 rabbits and 10 rats were served as the experimental animals. A slow recompressiondecompression test and an explosive decompression test were applied to the animals, respectively. And the effects of the given tests on the animals were discussed. Results: The slow recompression-decompression did not cause an obvious lung injury, but the explosive decompression did cause lung injuries in different degrees. The greater the decompression range was, the shorter the decompression duration was, and the heavier the lung injuries were. Conclusions: Explosive decompression can cause a similar lung injury as shock wave does. The primary mechanical causes of the lung injury might be a tensile strain or stress in the alveolar wall and the pulmonary surface's impacts on the inside wall of the chest.

  8. Unreacted Hugoniots for porous and liquid explosives

    Energy Technology Data Exchange (ETDEWEB)

    Gustavsen, R.L.; Sheffield, S.A.

    1993-08-01

    Numerous authors have measured the Hugoniots of a variety of granular explosives pressed to different densities. Each explosive at each density was typically then treated as a unique material having its own Hugoniot. By combining methods used by Hayes, Sheffield and Mitchell (for describing the Hugoniot of HNS at various densities) with Hermann`s P-{alpha} model, it is only necessary to know some thermodynamic constants or the Hugoniot of the initially solid material and the porous material sound speed to obtain accurate unreacted Hugoniots for the porous explosive. We discuss application of this method to several materials including HMX, PETN, TNT, and Tetryl, as well as HNS. We also show that the ``Universal Liquid Hugoniot`` can be used to calculate the unreacted Hugoniot for liquid explosives. With this method only the ambient pressure sound speed and density are needed to predict the Hugoniot. Applications presented include nitromethane and liquid TNT.

  9. Traumatic corneal endothelial rings from homemade explosives.

    Science.gov (United States)

    Ng, Soo Khai; Rudkin, Adam K; Galanopoulos, Anna

    2013-08-01

    Traumatic corneal endothelial rings are remarkably rare ocular findings that may result from blast injury. We present a unique case of bilateral traumatic corneal endothelial rings secondary to blast injury from homemade explosives. PMID:23474743

  10. Explosives Detection and Identification by PGNAA

    Energy Technology Data Exchange (ETDEWEB)

    E. H. Seabury; A. J. Caffrey

    2006-04-01

    The feasibility of using field-portable prompt gamma-ray neutron activation analysis (PGNAA) to detect and identify explosives in improvised nuclear devices has been studied computationally, using the Monte Carlo N-Particle (MCNP) code developed at Los Alamos National Laboratory. The Monte Carlo results, in turn were tested experimentally using explosive simulants and the PINS PGNAA system developed at Idaho National Laboratory (INL). The results of the MCNP calculations and PINS measurements have been previously reported. In this report we describe measurements performed on actual explosives and compare the results with calculations. The calculations and measurements were in good agreement and indicate that most explosives are readily distinguishable from one another by PGNAA

  11. Explosives Detection and Identification by PGNAA

    International Nuclear Information System (INIS)

    The feasibility of using field-portable prompt gamma-ray neutron activation analysis (PGNAA) to detect and identify explosives in improvised nuclear devices has been studied computationally, using the Monte Carlo N-Particle (MCNP) code developed at Los Alamos National Laboratory. The Monte Carlo results, in turn were tested experimentally using explosive simulants and the PINS PGNAA system developed at Idaho National Laboratory (INL). The results of the MCNP calculations and PINS measurements have been previously reported. In this report we describe measurements performed on actual explosives and compare the results with calculations. The calculations and measurements were in good agreement and indicate that most explosives are readily distinguishable from one another by PGNAA

  12. Isolator fragmentation and explosive initiation tests

    Energy Technology Data Exchange (ETDEWEB)

    Dickson, Peter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rae, Philip John [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Foley, Timothy J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Novak, Alan M. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Armstrong, Christopher Lee [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Baca, Eva V. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Gunderson, Jake Alfred [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-09-19

    Three tests were conducted to evaluate the effects of firing an isolator in proximity to a barrier or explosive charge. The tests with explosive were conducted without a barrier, on the basis that since any barrier will reduce the shock transmitted to the explosive, bare explosive represents the worst-case from an inadvertent initiation perspective. No reaction was observed. The shock caused by the impact of a representative plastic material on both bare and cased PBX 9501 is calculated in the worst-case, 1-D limit, and the known shock response of the HE is used to estimate minimum run-to-detonation lengths. The estimates demonstrate that even 1-D impacts would not be of concern and that, accordingly, the divergent shocks due to isolator fragment impact are of no concern as initiating stimuli.

  13. Numerical Simulation of Underwater Explosion Loads

    Institute of Scientific and Technical Information of China (English)

    XIN Chunliang; XU Gengguang; LIU Kezhong

    2008-01-01

    Numerical simulation of TNT underwater explosion was carried out with AUTODYN software.Influences of artificial viscosity and mesh density on simulation results were discussed.Detonation waves in explosive and shock wave in water during early time of explosion are high frequency waves.Fine meshes (less than 1 mm) in explosive and water nearby,and small linear viscosity coefficients and quadratic viscosity coefficients (0.02 and 0.1 respectively,1/10 of default values) are needed in numerical simulation model.According to these rules,numerical computing pressure profiles can match well with those calculated by Zamyshlyayev empirical formula.Otherwise peak pressure would be smeared off and upstream relative errors would be cumulated downstream to make downstream peak pressure lower.

  14. Gold recovery from low concentrations using nanoporous silica adsorbent

    Science.gov (United States)

    Aledresse, Adil

    The development of high capacity adsorbents with uniform porosity denoted 5%MP-HMS (5% Mercaptopropyl-Hexagonal Mesoporous Structure) to extract gold from noncyanide solutions is presented. The preliminary studies from laboratory simulated noncyanide gold solutions show that the adsorption capacities of these materials are among the highest reported. The high adsorption saturation level of these materials, up to 1.9 mmol/g (37% of the adsorbent weight) from gold chloride solutions (potassium tetrachloroaurate) and 2.9 mmol/g (57% of the adsorbent weight) from gold bromide solutions (potassium tetrabromoaurate) at pH = 2, is a noteworthy feature of these materials. This gold loading from [AuC4]- and [AuBr4 ]- solutions corresponds to a relative Au:S molar ratio of 2.5:1 and 3.8:1, respectively. These rates are significantly higher than the usual 1:1 (Au:S) ratio expected for metal ion binding with the material. The additional gold ions loaded have been spontaneously reduced to metallic gold in the mesoporous material. Experimental studies indicated high maximum adsorptions of gold as high as 99.9% recovery. Another promising attribute of these materials is their favourable adsorption kinetics. The MP-HMS reaches equilibrium (saturation) in less than 1 minute of exposure in gold bromide and less than 10 minutes in gold chloride. The MP-HMS materials adsorption is significantly improved by agitation and the adsorption capacity of Au (III) ions increases with the decrease in pH. The recovery of adsorbed gold and the regeneration of spent adsorbent were investigated for MP-HMS adsorbent. The regenerated adsorbent (MP-HMS) maintained its adsorption capacity even after repeated use and all the gold was successfully recovered from the spent adsorbent. For the fist time, a promising adsorbent system has been found that is capable of effectively concentrating gold thiosulphate complexes, whereas conventional carbon-inpulp (CIP) and carbon-in-leach (CIL) systems fail. The

  15. 30 CFR 77.1300 - Explosives and blasting.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Explosives and blasting. 77.1300 Section 77... Explosives and Blasting § 77.1300 Explosives and blasting. (a) No explosives, blasting agent, detonator, or any other related blasting device or material shall be stored, transported, carried, handled,...

  16. Remote monitoring of nuclear explosions during radio sounding of ionosphere over explosion place

    International Nuclear Information System (INIS)

    To solve the problem of non propagation of nuclear weapons it is necessary to develop the methods of remote detecting and monitoring of underground nuclear explosions too. At present , the basic method of underground nuclear explosions monitoring is seismic method. Because of decreasing of boundary of explosion power and development methods to decrease of seismic efficacy of explosions it is necessary the further development both as a seismic method as new independent methods of underground nuclear explosions monitoring. So the remote monitoring of explosions with helping radio physical method for measurement of slight blast waves over explosion place is promising. To determine all possibilities of that method it is necessary to work off the model of physical processes with using of experimental material. At the same time we can tell about some advantages of present method. The measurement of disturbance is releasing over explosion place and it does not depend from length of radio trace. Then seismic method measures the vibration of point of earth surface. Ionospheric method is integral method: the disturbances of ionosphere are produced by the whole epicenter region of explosion. As a result, the space inhomogeneities are averaging and the influence of stochastic factors is decreasing

  17. Effect of Explosive Sources on the Elastic Wave Field of Explosions in Soils

    Directory of Open Access Journals (Sweden)

    Chun Hua Bai

    2013-07-01

    Full Text Available A seismic wave is essentially an elastic wave, which propagates in the soil medium, with the strength of initial elastic wave being created by an explosion source that has a significant effect on seismic wave energy. In order to explore the explosive energy effect on output characteristics of the elastic wave field, four explosives with different work capacity (i.e., TNT, 8701, composition B and THL were used to study the effects of elastic wave pressure and rise time of stress wave to the peak value of explosions in soils. All the experimental data was measured under the same geological conditions using a self-designed pressure measuring system. This study was based on the analysis of the initial pressure of elastic waves from the energy output characteristics of the explosives. The results show that this system is feasible for underground pressure tests, and the addition of aluminum powder increases the pressure of elastic waves and energy release of explosions in soils. The explosive used as a seismic energy source in petroleum and gas exploration should have properties of high explosion heat and low volume of explosion gas products.Defence Science Journal, 2013, 63(4, pp.376-380, DOI:http://dx.doi.org/10.14429/dsj.63.2770

  18. Effect of Explosive Sources on the Elastic Wave Field of Explosions in Soils

    Directory of Open Access Journals (Sweden)

    Chun-Hua Bai

    2013-07-01

    Full Text Available A seismic wave is essentially an elastic wave, which propagates in the soil medium, with the strength of initial elastic wave being created by an explosion source that has a significant effect on seismic wave energy. In order to explore the explosive energy effect on output characteristics of the elastic wave field, four explosives with different work capacity (i.e., TNT, 8701, composition B and THL were used to study the effects of elastic wave pressure and rise time of stress wave to the peak value of explosions in soils. All the experimental data was measured under the same geological conditions using a self-designed pressure measuring system. This study was based on the analysis of the initial pressure of elastic waves from the energy output characteristics of the explosives. The results show that this system is feasible for underground pressure tests, and the addition of aluminum powder increases the pressure of elastic waves and energy release of explosions in soils. The explosive used as a seismic energy source in petroleum and gas exploration should have properties of high explosion heat and low volume of explosion gas products.

  19. Wave generations from confined explosions in rocks

    OpenAIRE

    C. L. Liu; Ahrens, Thomas J.

    1998-01-01

    In order to record P- and S-waves generated from confined explosions in rocks in the laboratory, a method is developed based on the interactions between incident P- and SV-waves and free-surfaces of rocks. The relations between particle displacements of incident P- and SV-waves, and the strains measured using strain gauges attached on free-surfaces of rocks are analytically derived. P- and SV-waves generated from confined explosions in Bedford limestone are recorded.

  20. Scaling the electromagnetically driven explosive shock simulator

    Science.gov (United States)

    Persh, Robert I.

    1987-01-01

    A heavy payload electromagnetically driven explosive shock simulator, referred to as EDESS-3, has been assembled and characterized at the Navel research Weapons Center. EDESS-3 is the logical outgrowth of the earlier EDESS 1 and 2 simulator work which explored the use of electrical pulse power technology for the generation of explosive like shocks. The features of the EDESS-3 are presented, and designs for the next generation of EDESS machines are introduced.