Linear-scaling quantum mechanical methods for excited states.

Science.gov (United States)

Yam, ChiYung; Zhang, Qing; Wang, Fan; Chen, GuanHua

2012-05-21

The poor scaling of many existing quantum mechanical methods with respect to the system size hinders their applications to large systems. In this tutorial review, we focus on latest research on linear-scaling or O(N) quantum mechanical methods for excited states. Based on the locality of quantum mechanical systems, O(N) quantum mechanical methods for excited states are comprised of two categories, the time-domain and frequency-domain methods. The former solves the dynamics of the electronic systems in real time while the latter involves direct evaluation of electronic response in the frequency-domain. The localized density matrix (LDM) method is the first and most mature linear-scaling quantum mechanical method for excited states. It has been implemented in time- and frequency-domains. The O(N) time-domain methods also include the approach that solves the time-dependent Kohn-Sham (TDKS) equation using the non-orthogonal localized molecular orbitals (NOLMOs). Besides the frequency-domain LDM method, other O(N) frequency-domain methods have been proposed and implemented at the first-principles level. Except one-dimensional or quasi-one-dimensional systems, the O(N) frequency-domain methods are often not applicable to resonant responses because of the convergence problem. For linear response, the most efficient O(N) first-principles method is found to be the LDM method with Chebyshev expansion for time integration. For off-resonant response (including nonlinear properties) at a specific frequency, the frequency-domain methods with iterative solvers are quite efficient and thus practical. For nonlinear response, both on-resonance and off-resonance, the time-domain methods can be used, however, as the time-domain first-principles methods are quite expensive, time-domain O(N) semi-empirical methods are often the practical choice. Compared to the O(N) frequency-domain methods, the O(N) time-domain methods for excited states are much more mature and numerically stable, and

Electron and photon-beam induced reactions of adsorbed disilane: Low-temperature thin-film growth

International Nuclear Information System (INIS)

Bozso, F.; Avouris, Ph.

1991-01-01

Electrons and photons of sufficient energy can cause fragmentation and desorption of adsorbed molecules or fragments of them, by inducing electronic excitations to dissociative states. The surface species after such excitations are mostly of highly reactive radical character, which readily react with the substrate and with other molecular or radical species in the adsorbed layer. This paper discusses the adsorption, thermal and electron/photon-beam induced reactions of disilane, oxygen and ammonia on Si(111)-7x7, and the electron/photon-induced growth of silicon, silicon dioxide and silicon nitride films at 100K

Clarification of the mechanism of sulfur trioxide electrolysis. Evaluation of SO3 and O atom adsorbed on Pt surface

International Nuclear Information System (INIS)

Suzuki, Chikashi; Nakagiri, Toshio

2008-01-01

We developed a hybrid thermo-chemical process, which included a SO 3 electrolysis process utilizing the heat supplied by a fast breeder reactor (FBR), as a new hydrogen production process. To clarify the mechanism of SO 3 electrolysis, we evaluated the electronic states of SO 3 and O atom adsorbed on the Pt (111) surface using first-principles calculations with a slab model. Moreover, we evaluated the chemical bonding states of SO 3 and adsorbed O using molecular orbital calculation on the basis of the calculations using a slab model. We found that there were two stable adsorbed SO 3 configurations on the Pt surface. From the molecular orbital calculation, it was found that the S-O bond became weak by SO 3 absorption, and it was conjectured that SO 3 dissociation proceeded through the intermediate state of adsorbed SO 2 and adsorbed O on the Pt surface. Moreover, we derived the O coverage considering the adsorbed SO 2 and evaluated the influence of SO 3 adsorption energy on the O coverage. (author)

Modal Testing of Mechanical Structures subject to Operational Excitation Forces

DEFF Research Database (Denmark)

Møller, N.; Brincker, Rune; Herlufsen, H.

2001-01-01

Operational Modal Analysis also known as Output Only Modal Analysis has in the recent years been used for extracting modal parameters of civil engineering structures and is now becoming popular for mechanical structures. The advantage of the method is that no artificial excitation need to be appl......Operational Modal Analysis also known as Output Only Modal Analysis has in the recent years been used for extracting modal parameters of civil engineering structures and is now becoming popular for mechanical structures. The advantage of the method is that no artificial excitation need...

Excitation of autoionizing states of helium by 100 keV proton impact: II. Excitation cross sections and mechanisms of excitation

Energy Technology Data Exchange (ETDEWEB)

Godunov, A.L. [Department of Physics, Tulane University, New Orleans, LA 70118-5698 (United States); Ivanov, P.B.; Schipakov, V.A. [Troitsk Institute of Innovation and Fusion Research Troitsk, Moscow region, 142092 (Russian Federation); Moretto-Capelle, P.; Bordenave-Montesquieu, D.; Bordenave-Montesquieu, A. [Laboratoire Collisions, Agregats, Reactivite, IRSAMC, UMR 5589, CNRS-Universite Paul Sabatier, 31062 Toulouse Cedex (France)

2000-03-14

Mechanisms of two-electron excitation of the (2s{sup 2}){sup 1} S, (2p{sup 2} ){sup 1} D and (2s2p){sup 1} P autoionizing states of helium are studied both experimentally and theoretically. It is shown that an explicit introduction of a kinematic factor, with a process-specific phase leads to a productive parametrization of experimental cross sections of ionization, allowing one to extract cross sections of excitation of autoionizing states. Using a new fitting procedure together with the proposed parametrization made it possible to obtain the excitation cross sections and magnetic sublevel population from electron spectra as well as, for the first time, to resolve the contribution of resonance and interference components to resonance profiles. Interference with direct ionization is shown to contribute significantly into resonance formation even for backward ejection angles. We demonstrate theoretically that the excitation cross sections thus extracted from experimental electron spectra hold information about the interaction of autoionizing states with an adjacent continuum. (author)

SERS and DFT study of p-hydroxybenzoic acid adsorbed on colloidal silver particles.

Science.gov (United States)

Chen, Y; Chen, S J; Li, S; Wei, J J

2015-10-16

In this study, normal Raman spectra of p—hydroxybenzoic acid (PHBA) powder and its surface—enhanced Raman scattering (SERS) spectra in silver colloidal solutions were measured under near infrared excitation conditions. In theoretical calculation, two models of PHBA adsorbed on the surfaces of silver nanoparticles were established. The Raman frequencies of these two models using density functional theory (DFT) method were calculated, and compared with the experimental results. It was found that the calculated Raman frequencies were in good agreement with experimental values, which indicates that there are two enhanced mechanism physical (electromagnetic, EM) enhancement and chemical (charge—transfer, CT) enhancement, in silver colloidal solutions regarding SERS effect. Furthermore, from high—quality SERS spectrum of PHBA obtained in silver colloids, we inferred that PHBA molecules in silver colloids adsorb onto the metal surfaces through carboxyl at a perpendicular orientation. The combination of SERS spectra and DFT calculation is thus useful for studies of the adsorption—orientation of a molecule on a metal colloid.

Mechanism of spiral formation in heterogeneous discretized excitable media.

Science.gov (United States)

Kinoshita, Shu-ichi; Iwamoto, Mayuko; Tateishi, Keita; Suematsu, Nobuhiko J; Ueyama, Daishin

2013-06-01

Spiral waves on excitable media strongly influence the functions of living systems in both a positive and negative way. The spiral formation mechanism has thus been one of the major themes in the field of reaction-diffusion systems. Although the widely believed origin of spiral waves is the interaction of traveling waves, the heterogeneity of an excitable medium has recently been suggested as a probable cause. We suggest one possible origin of spiral waves using a Belousov-Zhabotinsky reaction and a discretized FitzHugh-Nagumo model. The heterogeneity of the reaction field is shown to stochastically generate unidirectional sites, which can induce spiral waves. Furthermore, we found that the spiral wave vanished with only a small reduction in the excitability of the reaction field. These results reveal a gentle approach for controlling the appearance of a spiral wave on an excitable medium.

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...

The molecular mechanism of mediation of adsorbed serum proteins to endothelial cells adhesion and growth on biomaterials.

Science.gov (United States)

Yang, Dayun; Lü, Xiaoying; Hong, Ying; Xi, Tingfei; Zhang, Deyuan

2013-07-01

To explore molecular mechanism of mediation of adsorbed proteins to cell adhesion and growth on biomaterials, this study examined endothelial cell adhesion, morphology and viability on bare and titanium nitride (TiN) coated nickel titanium (NiTi) alloys and chitosan film firstly, and then identified the type and amount of serum proteins adsorbed on the three surfaces by proteomic technology. Subsequently, the mediation role of the identified proteins to cell adhesion and growth was investigated with bioinformatics analyses, and further confirmed by a series of cellular and molecular biological experiments. Results showed that the type and amount of adsorbed serum proteins associated with cell adhesion and growth was obviously higher on the alloys than on the chitosan film, and these proteins mediated endothelial cell adhesion and growth on the alloys via four ways. First, proteins such as adiponectin in the adsorbed protein layer bound with cell surface receptors to generate signal transduction, which activated cell surface integrins through increasing intracellular calcium level. Another way, thrombospondin 1 in the adsorbed protein layer promoted TGF-β signaling pathway activation and enhanced integrins expression. The third, RGD sequence containing proteins such as fibronectin 1, vitronectin and thrombospondin 1 in the adsorbed protein layer bound with activated integrins to activate focal adhesion pathway, increased focal adhesion formation and actin cytoskeleton organization and mediated cell adhesion and spreading. In addition, the activated focal adhesion pathway promoted the expression of cell growth related genes and resulted in cell proliferation. The fourth route, coagulation factor II (F2) and fibronectin 1 in the adsorbed protein layer bound with cell surface F2 receptor and integrin, activated regulation of actin cytoskeleton pathway and regulated actin cytoskeleton organization. Copyright © 2013 Elsevier Ltd. All rights reserved.

Studies on the substrate mediated vibrational excitation of CO/Si(100) by means of SFG spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Han, Xu; Lass, Kristian; Balgar, Thorsten; Hasselbrink, Eckart [Universitaet Duisburg-Essen, Fachbereich Chemie, 45117 Essen (Germany)

2009-07-01

Vibrational excitations of adsorbates play an important role in chemical reaction dynamics. In the past decade CO on solid surfaces was chosen as adequate model system for studying vibrational relaxation dynamics. Our work is focused on the energy dissipation of vibrationally excited CO adsorbed on a silicon surface by means of IR/Vis sum frequency generation (SFG) spectroscopy. Here we present studies on substrate mediated excitation of vibrational modes of CO on Si(100) induced by UV radiation. We suppose the observation of highly excited internal stretch vibrations of CO caused by hot electrons generated within the silicon substrate.

Krypton retention on solid adsorbents

International Nuclear Information System (INIS)

Monson, P.R. Jr.

1980-01-01

Radioactive krypton-85 is released to the atmosphere in the off-gas from nuclear reprocessing plants. Three main methods have been suggested for removal of krypton from off-gas streams: cryogenic distillation; fluorocarbon absorption; and adsorption on solid sorbents. Use of solid adsorbents is the least developed of these methods, but offers the potential advantages of enhanced safety and lower operating costs. An experimental laboratory program was developed that will be used to investigate systematically many solid adsorbents (such as zeolites, i.e., mordenites) for trapping krypton in air. The objective of this investigation is to find an adsorbent that is more economical than silver-exchanged mordenite. Various physical and chemical characteristics such as adsorption isotherms, decontamination factors, co-adsorption, regeneration, and the mechanism and kinetics of noble gas adsorption were used to characterize the adsorbents. In the experimental program, a gas chromatograph using a helium ionization detector was used to measure the krypton in air before and after the adsorbent bed. This method can determine directly decontamination factors greater than 100

Mechanism of calcium oxide excitation by atom hydrogen

International Nuclear Information System (INIS)

Kharlamov, V.F.

1991-01-01

Heterogeneous recombination of hydrogen atoms on the surface of calcium oxide proceeds according to the Langmuir-Hinshelwood mechanism with participation of atoms in two different states, belonging to adsorption centres of the same type. CaO excitation is broughty about by vibration-electron transitions during associative desorption of H 2 molecules

Effect of excitation direction on cochlear macro-mechanics during bone conduction stimulation

Science.gov (United States)

Kamieniecki, Konrad; Tudruj, Sylwester; Piechna, Janusz; Borkowski, Paweł

2018-05-01

In many instances of hearing loss, audiological improvement can be made via direct excitation of a temporal bone (i.e., bone conduction). In order to design better and more efficient devices, the macro-mechanics of the bone conduction hearing pathway must be better understood. Based on previous empirical work, numerical models are useful. In this work, we present results of a time-domain Fluid Structure Interaction model that describes stimulation of the bone conduction pathway. The cochlea was modelled as uncoiled and consisted of an oval window, a round window, a basilar membrane and a helicotrema. In order to monitor pressure waves in the perilymph, the fluid was considered compressible. The excitation, in form of sinusoidal velocity, was applied to the cochlea bony walls. The system was excited in three perpendicular directions: along the basilar membrane, perpendicularly to the membrane and transversely to the membrane. The numerical simulation examined which stimulation direction maximally excited the basilar membrane, the pressure distributions for each excitation direction, and the associated mechanics.

Vibratory synchronization transmission of a cylindrical roller in a vibrating mechanical system excited by two exciters

Science.gov (United States)

Zhang, Xueliang; Wen, Bangchun; Zhao, Chunyu

2017-11-01

In present work vibratory synchronization transmission (VST) of a cylindrical roller with dry friction in a vibrating mechanical system excited by two exciters, is studied. Using the average method, the criterion of implementing synchronization of two exciters and that of ensuring VST of a roller, are achieved. The criterion of stability of the synchronous states satisfies the Routh-Hurwitz principle. The influences of the structural parameters of the system to synchronization and stability, are discussed numerically, which can be served as the theoretical foundation for engineering designs. An experiment is carried out, which approximately verify the validity of the theoretical and numerical results, as well as the feasibility of the method used. Utilizing the VST theory of a roller, some types of vibrating crushing or grinding equipments, etc., can be designed.

Adsorption mechanism of microcrystalline cellulose as green adsorbent for the removal of cationic methylene blue dye

International Nuclear Information System (INIS)

Tan, K.B.; Salamatinia, B.

2016-01-01

The adsorption mechanism of pure cellulose is yet to be explored. Thus, in this study, the adsorption mechanism of Microcrystalline Cellulose (MCC), a polysaccharide which is renewable, low cost and non-toxic, was studied on the adsorption of model dye Methylene blue (MB). It was found that the main adsorption mechanism of MB on MCC was due to the electrostatic attraction between the positively charged MB dye and negatively charged MCC. Thus, physical adsorption was the dominant effect, since electrostatic attraction is categorized as physical adsorption. This was verified by Dubinin-Radushkevich isotherm, whereby mean free energy adsorption value was found to be less than 8 kJ/mol. The values of Gibbs free energy for thermodynamics studies were found to be within the range of -20 kJ/mol and 0 kJ/mol, which also indicated physical adsorption. It was due to the electrostatic attraction as adsorption mechanism of this adsorption process which resulted rapid adsorption of MB dye. It was found that equilibrium dye concentration was achieved between 1-3 minutes, depending on the adsorption temperature. The rapid adsorption, as compared to a lot of materials, showed the potential of MCC as the future of green adsorbent. The adsorption of Methylene Blue on MCC fitted well in Langmuir Isotherm, with R2 values of higher than 0.99, while fitted moderately in Freundlich Isotherm, with R2 values between 0.9224 and 0.9223. Comparatively, the adsorption of MB on MCC fitted best Langmuir Isotherm as compared to Freundlich Isotherm which monolayer adsorption occurred at the homogenous surface of MCC. This also indicated adsorbed MB molecules do not interact with each other at neighboring adsorption sites. The maximum adsorption capacity calculated from Langmuir Isotherm was found to be 4.95 mg/g. Despite the potential of MCC as green adsorbent, the challenge of low adsorption capacity has to be addressed in the future. (author)

Electro-mechanical impact system excited by a source of limited power

Czech Academy of Sciences Publication Activity Database

Půst, Ladislav

2008-01-01

Roč. 15, č. 6 (2008), s. 1-10 ISSN 1802-1484 R&D Projects: GA ČR GA101/06/0063 Institutional research plan: CEZ:AV0Z20760514 Keywords : mechanical oscillations * impacts * limited power of exciter * electro-mechanical interaction Subject RIV: BI - Acoustics

Photolysis mechanism of aqueous tyrosine upon excitation of the second absorption band

International Nuclear Information System (INIS)

Shimizu, O.

1984-01-01

The formation mechanism of tyrosinyl radical was studied for aqueous solutions of tyrosine under irradiation at 235 nm which falls into the second absorption band. The work is based upon the analysis of the rate of bityrosine production for steady-state excitation at low intensity. The results indicate that monophotonic O-H bond cleavage of tyrosine, presumably involving the upper excited triplet state, is the initial photoprocess leading to the tyrosinyl radical when tyrosine is excited into the second absorption band. (author)

Transporting method for adsorbing tower and the adsorbing tower

International Nuclear Information System (INIS)

Shimokawa, Nobuhiro.

1996-01-01

A cylindrical plastic bag is disposed to the upper surface of an adsorbing tower so as to surround a suspending piece. One opening of the bag is sealed, and other opening is secured in a sealed state to a bag holding portion disposed to glove box at a gate for the adsorbing tower box. The adsorbing tower is transported into the glove box, and after the completion of the operation of the adsorbing tower, the adsorbing tower is taken out in a state that the bag is restricted and sealed at a portion below the adsorbing tower. The bag may be made of a vinyl plastic, the bag holding portion may be a short-cylindrical protrusion, and may have an O-ring groove at the outer surface. Even if the adsorbing tower is heavy, the adsorbing tower can be carried out easily in a state where it is sealed gas tightly. (N.H.)

Heat transfer between adsorbate and laser-heated hot electrons

International Nuclear Information System (INIS)

Ueba, H; Persson, B N J

2008-01-01

Strong short laser pulses can give rise to a strong increase in the electronic temperature at metal surfaces. Energy transfer from the hot electrons to adsorbed molecules may result in adsorbate reactions, e.g. desorption or diffusion. We point out the limitations of an often used equation to describe the heat transfer process in terms of a friction coupling. We propose a simple theory for the energy transfer between the adsorbate and hot electrons using a newly introduced heat transfer coefficient, which depends on the adsorbate temperature. We calculate the transient adsorbate temperature and the reaction yield for a Morse potential as a function of the laser fluency. The results are compared to those obtained using a conventional heat transfer equation with temperature-independent friction. It is found that our equation of energy (heat) transfer gives a significantly lower adsorbate peak temperature, which results in a large modification of the reaction yield. We also consider the heat transfer between different vibrational modes excited by hot electrons. This mode coupling provides indirect heating of the vibrational temperature in addition to the direct heating by hot electrons. The formula of heat transfer through linear mode-mode coupling of two harmonic oscillators is applied to the recent time-resolved study of carbon monoxide and atomic oxygen hopping on an ultrafast laser-heated Pt(111) surface. It is found that the maximum temperature of the frustrated translation mode can reach high temperatures for hopping, even when direct friction coupling to the hot electrons is not strong enough

Nontrivial effects of high-frequency excitation for strongly damped mechanical systems

DEFF Research Database (Denmark)

Fidlin, Alexander; Thomsen, Jon Juel

Some nontrivial effects are investigated, which can occur if strongly damped mechanical systems are subjected to strong high-frequency (HF) excitation. The main result is a theoretical prediction, supported by numerical simulation, that for such systems the (quasi-)equilibrium states can change...... that can be substantial (depending on the strength of the HF excitation) for finite values of the damping. The analysis is focused on the differences between the classic results for weakly damped systems, and new effects for which the strong damping terms are responsible. The analysis is based...... on a slightly modified averaging technique, and includes an elementary example of an elliptically excited pendulum for illustration, alongside with a generalization to a broader class of strongly damped dynamical systems with HF excitation. As an application example, the nontrivial behavior of a classical...

Ultrafast time-resolved electron diffraction on adsorbate systems on silicon surfaces. Vibrational excitation in monllayers and dynamics of phase transitions; Ultraschnelle zeitaufgeloeste Elektronenbeugung an Adsorbatsystemen auf Siliziumoberflaechen. Vibrationsanregung in Monolagen und Dynamik von Phasenuebergaengen

Energy Technology Data Exchange (ETDEWEB)

Moellenbeck, Simone

2011-04-11

In the present work ultra fast time resolved electron diffraction (TR-RHEED) at various adsorbate systems on silicon (Si) substrates was performed. Using the Debye-Waller-effect, the vibrational amplitude of the excited adsorbate atoms can be directly observed in the experiments as a function of time. For a coverage of 4/3 monolayers Lead (Pb) on Si(1 1 1) forms a ({radical}(3) x {radical}(3))-reconstruction. The transient intensity evolution of the diffraction spots is recorded in a TR-RHEED-experiment. After excitation with a fs-laser pulse the intensity decreases due to the Debye-Waller-effect. The temporal behavior of the de-excitation process can be described with two exponential functions: a short time constant of 100 ps and a long one of 2800 ps. The two time constants can be assigned to two different phonon modes of the Pb-adsorbate. The huge difference between the two time constants and thus difference in the coupling to the substrate is explained by the bonding geometry in the structural model. To confirm this possible explanation, further TR-RHEED-experiments for the ({radical}(7) x {radical}(3))-reconstruction of Pb on Si(1 1 1) were performed. The ({radical}(7) x {radical}(3))-reconstruction with a coverage of 1.2 monolayers shows comparable structural elements. The transient intensity evolution can be described with the identical two time constants. In addition, first experiments on the {beta} ({radical}(3) x {radical}(3))-phase of Pb/Si(1 1 1) are presented. This {beta} ({radical}(3) x {radical}(3))-reconstruction, with a coverage of 1/3 monolayers of Pb, shows a phase transition to a (3 x 3)-reconstruction, which was observed in the experiments. Further investigated adsorbate systems are: ({radical}(3) x {radical}(3))Ag/Si(1 1 1), ({radical}(3) x {radical}(3))In/Si(1 1 1), ({radical}(31) x {radical}(31))In/Si(1 1 1), and ({radical}(3) x {radical}(3))Bi/Si(1 1 1). In the second part of the present work the structural dynamics of strongly driven

Photodissociation of HBr/LiF(001) - A quantum mechanical model

Science.gov (United States)

Seideman, Tamar

1993-01-01

The photodissociation dynamics of HBr adsorbed on an LiF(001) surface is studied using time-independent quantum mechanics. The photodissociation line shape and the Br(2P(1/2))/Br(2P(3/2)) yield ratio are computed and compared with the corresponding quantities for gas phase photodissociation. The angular distribution of the hydrogen photofragments following excitation of adsorbed HBr is computed and found to agree qualitatively with experimental data. The effect of polarization of the photon is illustrated and discussed. We find the field polarization to affect significantly the magnitude of the photodissociation signal but not the angular dependence of the photofragment distribution, in agreement with experiment and in accord with expectations for a strongly aligned adsorbed phase.

Photodissociation of HBr/LiF(001): A quantum mechanical model

Science.gov (United States)

Seideman, Tamar

1993-01-01

The photodissociation dynamics of HBr adsorbed on a LiF(001) surface is studied using time-independent quantum mechanics. The photodissociation lineshape and the Br(P(sub 1/2)-2)/Br(P(sub 3/2)-2) yield ratio are computed and compared with the corresponding quantities for gas phase photodissociation. The angular distribution of the hydrogen photofragments following excitation of adsorbed HBr is computed and found to agree qualitatively with experimental data. The effect of polarization of the photon is illustrated and discussed. The field polarization is found to affect significantly the magnitude of the photodissociation signal but not the angular dependence of the photofragment distribution, in agreement with experiment and in accord with expectations for a strongly aligned adsorbed phase.

Excited hydrogen bonds in the molecular mechanism of muscle contraction.

Science.gov (United States)

Bespalova, S V; Tolpygo, K B

1991-11-21

The mechanism of muscle contraction is considered. The hydrolysis of an ATP molecule is assumed to produce the excitation of hydrogen bonds A--H...B between electronegative atoms A and B, which are contained in the myosin head and actin filament. This excitation energy epsilon f depends on the interatomic distance AB = R and generates the tractive force f = -delta epsilon f/delta R, that makes atoms AB approach each other. The swing of the myosin head results in macroscopic mutual displacement of actin and myosin polymers. The motion of the actin filament under the action of this force is studied. The conditions under which a considerable portion of the excitation energy converts into the potential tension energy of the actin filament are analysed, and the probability of higher muscle efficiency existence is discussed.

Chitin Adsorbents for Toxic Metals: A Review

Directory of Open Access Journals (Sweden)

Ioannis Anastopoulos

2017-01-01

Full Text Available Wastewater treatment is still a critical issue all over the world. Among examined methods for the decontamination of wastewaters, adsorption is a promising, cheap, environmentally friendly and efficient procedure. There are various types of adsorbents that have been used to remove different pollutants such as agricultural waste, compost, nanomaterials, algae, etc., Chitin (poly-β-(1,4-N-acetyl-d-glucosamine is the second most abundant natural biopolymer and it has attracted scientific attention as an inexpensive adsorbent for toxic metals. This review article provides information about the use of chitin as an adsorbent. A list of chitin adsorbents with maximum adsorption capacity and the best isotherm and kinetic fitting models are provided. Moreover, thermodynamic studies, regeneration studies, the mechanism of adsorption and the experimental conditions are also discussed in depth.

Nontrivial effects of high-frequency excitation for strongly damped mechanical systems

DEFF Research Database (Denmark)

Fidlin, Alexander; Thomsen, Jon Juel

2008-01-01

Some non-trivial effects are investigated, which can occur if strongly damped mechanical systems are subjected to strong high-frequency (HF) excitation. The main result is a theoretical prediction, supported by numerical simulation, that for such systems the (quasi-)equilibrium states can change...... that can be substantial depending on the strength of the HF excitation) for finite values of the damping. The analysis is focused on the differences between the classic results for weakly damped systems, and new effects for which the strong damping terms are responsible. The analysis is based on a slightly...... modified averaging technique, and includes an elementary example of an elliptically excited pendulum for illustration, alongside with a generalization to a broader class of strongly damped dynamical systems with HF excitation. As an application example, the nontrivial behavior of a classical optimally...

The state of physically adsorbed substances in microporous adsorbents

International Nuclear Information System (INIS)

Fomkin, A.A.

1987-01-01

Xe, Kr, Ar, CF 3 Cl, CH 4 adsorption in NaX microporous zeolite of 0.98 Na 2 OxAl 2 O 3 x2.36SiO 2 x0.02H 2 O is studied. Some properties of adsorbates (density, coefficients of expansion, enthalpy, heat capacity) are determined and discussed. The adsorbate in the microporous adsorbent is shown to be a particular state of a substance. Liniarity of adsorption isosteres and sharp changes during isosteric heat capacity of the adsorbate points to the fact that in microporous adsorbents phase transformations of the second type are possible

pH-controlled quaternary ammonium herbicides capture/release by carboxymethyl-β-cyclodextrin functionalized magnetic adsorbents: Mechanisms and application

Energy Technology Data Exchange (ETDEWEB)

Liu, Chang; Wang, Peng [Department of Applied Chemistry, China Agricultural University, No. 2 West Yuanmingyuan Road, Beijing 100193 (China); Shen, Zhigang [Zhong Nong Fa Seed Industry Group Co. Ltd, Beijing 600313 (China); Liu, Xueke; Zhou, Zhiqiang [Department of Applied Chemistry, China Agricultural University, No. 2 West Yuanmingyuan Road, Beijing 100193 (China); Liu, Donghui, E-mail: liudh@cau.edu.cn [Department of Applied Chemistry, China Agricultural University, No. 2 West Yuanmingyuan Road, Beijing 100193 (China)

2015-12-11

In our work, the pH-controlled magnetic solid phase extraction for the determination of paraquat and diquat was introduced firstly. Furthermore, to clarify the mechanism of carboxymethyl-β-cyclodextrin functionalized magnetic adsorbents, we studied the pH-responsive supramolecular interaction between carboxymethyl-β-cyclodextrin (CM-β-CD) and paraquat/diquat by ultraviolet–visible (UV–vis) spectroscopy and nuclear magnetic resonance (NMR) experiment, and the energy-minimized structures were also obtained. Then, the functional group CM-β-CD was modified on the surface of magnetic materials to synthesize the adsorbent. The Fourier transform infrared spectrum (FT-IR) results proved the successful modification of CM-β-CD. Thus, this absorbent was applied for the determination of paraquat and diquat in water. Under the optimal condition, limits of detection (LODs) of paraquat and diquat were 0.8 μg L{sup −1} and 0.9 μg L{sup −1}, relative standard deviations (RSD) and recoveries varied 0.7–4.6% and 86.5–106.6%, respectively. Good recoveries (70.2–100.0%) and low RSD (1.7–9.6%) were achieved in analyzing spiked water samples. Furthermore, with the capillary electrophoresis (CE) as the analyser, the whole analytical process did not need the attendance of organic solvents. - Highlights: • The carboxymethyl-β-cyclodextrin functionalized magnetic adsorbents were synthesized. • The adsorbents could capture or release quaternary ammonium herbicides by changing pH. • The adsorbents were applied in the analysis of real water samples. • There is no attendance of organic solvents in the whole analysis process.

Dissociation pathways of a single dimethyl disulfide on Cu(111): Reaction induced by simultaneous excitation of two vibrational modes

Energy Technology Data Exchange (ETDEWEB)

Motobayashi, Kenta, E-mail: kmotobayashi@cat.hokudai.ac.jp [Catalysis Research Center, Hokkaido University, Sapporo 001-0021 (Japan); Department of Advanced Materials Science, The University of Tokyo, Kashiwa 277-8561 (Japan); Surface and Interface Science Laboratory, RIKEN, Wako 351-0198 (Japan); Kim, Yousoo [Surface and Interface Science Laboratory, RIKEN, Wako 351-0198 (Japan); Arafune, Ryuichi [International Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba 305-0044 (Japan); Ohara, Michiaki; Ueba, Hiromu; Kawai, Maki, E-mail: maki@k.u-tokyo.ac.jp [Department of Advanced Materials Science, The University of Tokyo, Kashiwa 277-8561 (Japan)

2014-05-21

We present a novel reaction mechanism for a single adsorbed molecule that proceeds via simultaneous excitation of two different vibrational modes excited by inelastic tunneling electrons from a scanning tunneling microscope. Specifically, we analyze the dissociation of a single dimethyl disulfide (DMDS, (CH{sub 3}S){sub 2}) molecule on Cu(111) by using a versatile theoretical method, which permits us to simulate reaction rates as a function of sample bias voltage. The reaction is induced by the excitation of C-H stretch and S-S stretch modes by a two-electron process at low positive bias voltages. However, at increased voltages, the dissociation becomes a single-electron process that excites a combination mode of these stretches, where excitation of the C-H stretch is the energy source and excitation of the S-S stretch mode enhances the anharmonic coupling rate. A much smaller dissociation yield (few orders of magnitude) at negative bias voltages is understood in terms of the projected density of states of a single DMDS on Cu(111), which reflects resonant excitation through the molecular orbitals.

Modeling adsorption: Investigating adsorbate and adsorbent properties

Science.gov (United States)

Webster, Charles Edwin

1999-12-01

Surface catalyzed reactions play a major role in current chemical production technology. Currently, 90% of all chemicals are produced by heterogeneously catalyzed reactions. Most of these catalyzed reactions involve adsorption, concentrating the substrate(s) (the adsorbate) on the surface of the solid (the adsorbent). Pore volumes, accessible surface areas, and the thermodynamics of adsorption are essential in the understanding of solid surface characteristics fundamental to catalyst and adsorbent screening and selection. Molecular properties such as molecular volumes and projected molecular areas are needed in order to convert moles adsorbed to surface volumes and areas. Generally, these molecular properties have been estimated from bulk properties, but many assumptions are required. As a result, different literature values are employed for these essential molecular properties. Calculated molar volumes and excluded molecular areas are determined and tabulated for a variety of molecules. Molecular dimensions of molecules are important in the understanding of molecular exclusion as well as size and shape selectivity, diffusion, and adsorbent selection. Molecular dimensions can also be used in the determination of the effective catalytic pore size of a catalyst. Adsorption isotherms, on zeolites, (crystalline mineral oxides) and amorphous solids, can be analyzed with the Multiple Equilibrium Analysis (MEA) description of adsorption. The MEA produces equilibrium constants (Ki), capacities (ni), and thermodynamic parameters (enthalpies, ΔHi, and entropies, ΔSi) of adsorption for each process. Pore volumes and accessible surface areas are calculated from the process capacities. Adsorption isotherms can also be predicted for existing and new adsorbate-adsorbent systems with the MEA. The results show that MEA has the potential of becoming a standard characterization method for microporous solids that will lead to an increased understanding of their behavior in gas

Quantum mechanics of excitation transport in photosynthetic complexes: a key issues review.

Science.gov (United States)

Levi, Federico; Mostarda, Stefano; Rao, Francesco; Mintert, Florian

2015-07-01

For a long time microscopic physical descriptions of biological processes have been based on quantum mechanical concepts and tools, and routinely employed by chemical physicists and quantum chemists. However, the last ten years have witnessed new developments on these studies from a different perspective, rooted in the framework of quantum information theory. The process that more, than others, has been subject of intense research is the transfer of excitation energy in photosynthetic light-harvesting complexes, a consequence of the unexpected experimental discovery of oscillating signals in such highly noisy systems. The fundamental interdisciplinary nature of this research makes it extremely fascinating, but can also constitute an obstacle to its advance. Here in this review our objective is to provide an essential summary of the progress made in the theoretical description of excitation energy dynamics in photosynthetic systems from a quantum mechanical perspective, with the goal of unifying the language employed by the different communities. This is initially realized through a stepwise presentation of the fundamental building blocks used to model excitation transfer, including protein dynamics and the theory of open quantum system. Afterwards, we shall review how these models have evolved as a consequence of experimental discoveries; this will lead us to present the numerical techniques that have been introduced to quantitatively describe photo-absorbed energy dynamics. Finally, we shall discuss which mechanisms have been proposed to explain the unusual coherent nature of excitation transport and what insights have been gathered so far on the potential functional role of such quantum features.

Direct observation of solid-phase adsorbate concentration profile in powdered activated carbon particle to elucidate mechanism of high adsorption capacity on super-powdered activated carbon.

Science.gov (United States)

Ando, Naoya; Matsui, Yoshihiko; Matsushita, Taku; Ohno, Koichi

2011-01-01

Decreasing the particle size of powdered activated carbon (PAC) by pulverization increases its adsorption capacities for natural organic matter (NOM) and polystyrene sulfonate (PSS, which is used as a model adsorbate). A shell adsorption mechanism in which NOM and PSS molecules do not completely penetrate the adsorbent particle and instead preferentially adsorb near the outer surface of the particle has been proposed as an explanation for this adsorption capacity increase. In this report, we present direct evidence to support the shell adsorption mechanism. PAC particles containing adsorbed PSS were sectioned with a focused ion beam, and the solid-phase PSS concentration profiles of the particle cross-sections were directly observed by means of field emission-scanning electron microscopy/energy-dispersive X-ray spectrometry (FE-SEM/EDXS). X-ray emission from sulfur, an index of PSS concentration, was higher in the shell region than in the inner region of the particles. The X-ray emission profile observed by EDXS did not agree completely with the solid-phase PSS concentration profile predicted by shell adsorption model analysis of the PSS isotherm data, but the observed and predicted profiles were not inconsistent when the analytical errors were considered. These EDXS results provide the first direct evidence that PSS is adsorbed mainly in the vicinity of the external surface of the PAC particles, and thus the results support the proposition that the increase in NOM and PSS adsorption capacity with decreasing particle size is due to the increase in external surface area on which the molecules can be adsorbed. Copyright © 2010 Elsevier Ltd. All rights reserved.

Excitation mechanisms for XUV and X-ray lasers

International Nuclear Information System (INIS)

El-Sherbini, T.M.; Arrubban, M.M.

1992-01-01

Two excitation mechanisms leading to lasing action in the extreme ultraviolet and soft X-ray spectral regions are proposed. Boron- like ions of Mg VIII, Al IX and Si X plasmas are used as the active laser material. The upper laser level is the metastable 1s 2 2s 2 4p( 2 p) state while the lower level is the short lived 1s 2 2s 2 3d( 2 D) state. (author). 10 refs, 1 fig., 3 tabs

Nonlinear Dynamic Analysis of Telescopic Mechanism for Truss Structure Bridge Inspection Vehicle Under Pedestrian Excitation

Directory of Open Access Journals (Sweden)

Wenwen Sui

Full Text Available Abstract Nonlinear dynamic analysis of an axially moving telescopic mechanism for truss structure bridge inspection vehicle under pedestrian excitation is carried out. A biomechanically inspired inverted-pendulum model is utilized to simplify the pedestrian. The nonlinear equations of motion for the beam-pedestrian system are derived using the Hamilton's principle. The equations are transformed into two ordinary differential equations by applying the Galerkin's method at the first two orders. The solutions to the equations are acquired by using the Newmark-β method associated with the Newton-Raphson method. The time-dependent feature of the eigenfunctions for the two beams are taken into consideration in the solutions. Accordingly, the equations of motion for a simplified system, in which the pedestrian is regarded as moving cart, are given. In the numerical examples, dynamic responses of the telescopic mechanism in eight conditions of different beam-telescoping and pedestrian-moving directions are simulated. Comparisons between the vibrations of the beams under pedestrian excitation and corresponding moving cart are carried out to investigate the influence of the pedestrian excitation on the telescopic mechanism. The results show that the displacement of the telescopic mechanism under pedestrian excitation is smaller than that under moving cart especially when the pedestrian approaches the beams end. Additionally, compared with moving cart, the pedestrian excitation can effectively strengthen the vibration when the beam extension is small or when the pedestrian is close to the beams end.

Highly effective removal of mercury and lead ions from wastewater by mercaptoamine-functionalised silica-coated magnetic nano-adsorbents: Behaviours and mechanisms

Energy Technology Data Exchange (ETDEWEB)

Bao, Shuangyou; Li, Kai; Ning, Ping [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, YunNan, KunMing, 650500 (China); Peng, Jinhui [Faculty of Metallurgical and Energy, Kunming University of Science and Technology, YunNan, KunMing 650500 (China); Jin, Xu [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, YunNan, KunMing, 650500 (China); Tang, Lihong, E-mail: luckyman@163.com [Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, YunNan, KunMing, 650500 (China)

2017-01-30

Highlights: • Highly effective removal of Hg(II) and Pb(II) ions from wastewater. • This adsorbent had multiple adsorption sites (sulfur and amine sites) on the surface. • This adsorbent had better tolerance to low pH for removal of Hg(II). • This new hybrid material was much cheaper and no secondary pollution. • This adsorbent shows notable advantages including easy separation and recyclability. - Abstract: A novel hybrid material was fabricated using mercaptoamine-functionalised silica-coated magnetic nanoparticles (MAF-SCMNPs) and was effective in the extraction and recovery of mercury and lead ions from wastewater. The properties of this new magnetic material were explored using various characterisation and analysis methods. Adsorbent amounts, pH levels and initial concentrations were optimised to improve removal efficiency. Additionally, kinetics, thermodynamics and adsorption isotherms were investigated to determine the mechanism by which the fabricated MAF-SCMNPs adsorb heavy metal ions. The results revealed that MAF-SCMNPs were acid-resistant. Sorption likely occurred by chelation through the amine group and ion exchange between heavy metal ions and thiol functional groups on the nanoadsorbent surface. The equilibrium was attained within 120 min, and the adsorption kinetics showed pseudo-second-order (R{sup 2} > 0.99). The mercury and lead adsorption isotherms were in agreement with the Freundlich model, displaying maximum adsorption capacities of 355 and 292 mg/g, respectively. The maximum adsorptions took place at pH 5–6 and 6–7 for Hg(II) and Pb(II), respectively. The maximum adsorptions were observed at 10 mg and 12 mg adsorbent quantities for Hg(II) and Pb(II), respectively. The adsorption process was endothermic and spontaneous within the temperature range of 298–318 K. This work demonstrates a unique magnetic nano-adsorbent for the removal of Hg(II) and Pb(II) from wastewater.

Electron-stimulated desorption of cesium atoms from cesium layers adsorbed on gold-covered tungsten

Energy Technology Data Exchange (ETDEWEB)

Ageev, V N; Kuznetsov, Yu A; Potekhina, N D, E-mail: kuznets@ms.ioffe.r [A F Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021, St Petersburg (Russian Federation)

2010-03-03

The electron-stimulated desorption (ESD) yields and energy distributions (ED) for neutral cesium atoms have been measured from cesium layers adsorbed on a gold-covered tungsten surface as a function of electron energy, gold film thickness, cesium coverage and substrate temperature. The measurements have been carried out using a time-of-flight method and surface ionization detector in the temperature range 160-300 K. A measurable ESD yield for Cs atoms is observed only after deposition of more than one monolayer of gold and cesium on a tungsten surface at a temperature T = 300 K, which is accompanied by the formation of a CsAu semiconductor film covered with a cesium atom monolayer. The Cs atom ESD yield as a function of incident electron energy has a resonant character and consists of two peaks, the appearance of which depends on both electron energy and substrate temperature. The first peak has an appearance threshold at an electron energy of 57 eV and a substrate temperature of 300 K that is due to Au 5p{sub 3/2} core level excitation in the substrate. The second peak appears at an electron energy of 24 eV and a substrate temperature of 160 K. It is associated with a Cs 5s core level excitation in the Cs adsorbed layer. The Au 5p{sub 3/2} level excitation corresponds to a single broad peak in the ED with a maximum at a kinetic energy of 0.45 eV at a substrate temperature T = 300 K, which is split into two peaks with maxima at kinetic energies of 0.36 and 0.45 eV at a substrate temperature of 160 K, associated with different Cs atom ESD channels. The Cs 5s level excitation leads to an ED for Cs atoms with a maximum at a kinetic energy of approx 0.57 eV which exists only at T < 240 K and low Cs concentrations. The mechanisms for all the Cs atom ESD channels are proposed and compared with the Na atom ESD channels in the Na-Au-W system.

Growth mechanism and magnon excitation in NiO nanowalls

Directory of Open Access Journals (Sweden)

Yang Chun

2011-01-01

Full Text Available Abstract The nanosized effects of short-range multimagnon excitation behavior and short-circuit diffusion in NiO nanowalls synthesized using the Ni grid thermal treatment method were observed. The energy dispersive spectroscopy mapping technique was used to characterize the growth mechanism, and confocal Raman scattering was used to probe the antiferromagnetic exchange energy J 2 between next-nearest-neighboring Ni ions in NiO nanowalls at various growth temperatures below the Neel temperature. This study shows that short spin correlation leads to an exponential dependence of the growth temperatures and the existence of nickel vacancies during the magnon excitation. Four-magnon configurations were determined from the scattering factor, revealing a lowest state and monotonic change with the growth temperature. PACS: 75.47.Lx; 61.82.Rx; 75.50.Tt; 74.25.nd; 72.10.Di

Growth mechanism and magnon excitation in NiO nanowalls

Science.gov (United States)

2011-01-01

The nanosized effects of short-range multimagnon excitation behavior and short-circuit diffusion in NiO nanowalls synthesized using the Ni grid thermal treatment method were observed. The energy dispersive spectroscopy mapping technique was used to characterize the growth mechanism, and confocal Raman scattering was used to probe the antiferromagnetic exchange energy J2 between next-nearest-neighboring Ni ions in NiO nanowalls at various growth temperatures below the Neel temperature. This study shows that short spin correlation leads to an exponential dependence of the growth temperatures and the existence of nickel vacancies during the magnon excitation. Four-magnon configurations were determined from the scattering factor, revealing a lowest state and monotonic change with the growth temperature. PACS: 75.47.Lx; 61.82.Rx; 75.50.Tt; 74.25.nd; 72.10.Di PMID:21824408

Room-temperature atomic layer deposition of ZrO{sub 2} using tetrakis(ethylmethylamino)zirconium and plasma-excited humidified argon

Energy Technology Data Exchange (ETDEWEB)

Kanomata, K. [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan); Japan Society for the Promotion of Science, 5-3-1 Kojimachi, Chiyoda-ku, Tokyo 102-0083 (Japan); Tokoro, K.; Imai, T.; Pansila, P.; Miura, M.; Ahmmad, B.; Kubota, S.; Hirahara, K. [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan); Hirose, F., E-mail: fhirose@yz.yamagata-u.ac.jp [Graduate School of Science and Engineering, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510 (Japan)

2016-11-30

Highlights: • RT-ALD of ZrO{sub 2} is developed using TEMAZ and plasma-excited humidified argon. • The plasma-excited humidified argon is effective in oxidizing the TEMAZ saturated ZrO{sub 2}. • We discuss the reaction mechanism of the RT-ZrO{sub 2} ALD. - Abstract: Room-temperature atomic layer deposition (ALD) of ZrO{sub 2} is developed with tetrakis(ethylmethylamino)zirconium (TEMAZ) and a plasma-excited humidified argon. A growth per cycle of 0.17 nm/cycle at room temperature is confirmed, and the TEMAZ adsorption and its oxidization on ZrO{sub 2} are characterized by IR absorption spectroscopy with a multiple internal reflection mode. TEMAZ is saturated on a ZrO{sub 2} surface with exposures exceeding ∼2.0 × 10{sup 5} Langmuir (1 Langmuir = 1.0 × 10{sup −6} Torr s) at room temperature, and the plasma-excited humidified argon is effective in oxidizing the TEMAZ-adsorbed ZrO{sub 2} surface. The IR absorption spectroscopy suggests that Zr-OH works as an adsorption site for TEMAZ. The reaction mechanism of room-temperature ZrO{sub 2} ALD is discussed in this paper.

Adsorbate-induced lifting of substrate relaxation is a general mechanism governing titania surface chemistry.

Science.gov (United States)

Silber, David; Kowalski, Piotr M; Traeger, Franziska; Buchholz, Maria; Bebensee, Fabian; Meyer, Bernd; Wöll, Christof

2016-09-30

Under ambient conditions, almost all metals are coated by an oxide. These coatings, the result of a chemical reaction, are not passive. Many of them bind, activate and modify adsorbed molecules, processes that are exploited, for example, in heterogeneous catalysis and photochemistry. Here we report an effect of general importance that governs the bonding, structure formation and dissociation of molecules on oxidic substrates. For a specific example, methanol adsorbed on the rutile TiO 2 (110) single crystal surface, we demonstrate by using a combination of experimental and theoretical techniques that strongly bonding adsorbates can lift surface relaxations beyond their adsorption site, which leads to a significant substrate-mediated interaction between adsorbates. The result is a complex superstructure consisting of pairs of methanol molecules and unoccupied adsorption sites. Infrared spectroscopy reveals that the paired methanol molecules remain intact and do not deprotonate on the defect-free terraces of the rutile TiO 2 (110) surface.

Mechanism for the Excited-State Multiple Proton Transfer Process of Dihydroxyanthraquinone Chromophores.

Science.gov (United States)

Zhou, Qiao; Du, Can; Yang, Li; Zhao, Meiyu; Dai, Yumei; Song, Peng

2017-06-22

The single and dual cooperated proton transfer dynamic process in the excited state of 1,5-dihydroxyanthraquinone (1,5-DHAQ) was theoretically investigated, taking solvent effects (ethanol) into account. The absorption and fluorescence spectra were simulated, and dual fluorescence exhibited, which is consistent with previous experiments. Analysis of the calculated IR and Raman vibration spectra reveals that the intramolecular hydrogen bonding interactions (O 20 -H 21 ···O 24 and O 22 -H 23 ···O 25 ) are strengthened following the excited proton transfer process. Finally, by constructing the potential energy surfaces of the ground state, first excited singlet state, and triplet state, the mechanism of the intramolecular proton transfer of 1,5-DHAQ can be revealed.

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

a large tolerance to monatomic surface steps on the Ag(110) surface. The observed behaviour is explained in terms of strong intermolecular hydrogen bonding and a strong surface-mediated directionality, assisted by a sufficient degree of molecular backbone flexibility. In contrast, the same kind of step......-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...... bonds to the surface, a situation which is also achieved on Ag(110) by annealing to 200 degrees C. These results show that the formation of particular self-assembled molecular nanostructures depends significantly on a subtle balance between the adsorbate-adsorbate and adsorbate-substrate interactions...

The mechanisms of Excited states in enzymes

DEFF Research Database (Denmark)

Petersen, Frederic Nicolas Rønne; Bohr, Henrik

2010-01-01

Enzyme catalysis is studied on the basis of excited state processes, which are of electronic, vibrational and thermal nature. The ways of achieving the excited state, such as photo-absorption and ligand binding, are discussed and exemplified by various cases of enzymes.......Enzyme catalysis is studied on the basis of excited state processes, which are of electronic, vibrational and thermal nature. The ways of achieving the excited state, such as photo-absorption and ligand binding, are discussed and exemplified by various cases of enzymes....

Experimental evaluation of analyte excitation mechanisms in the inductively coupled plasma

International Nuclear Information System (INIS)

Lehn, Scott A.; Hieftje, Gary M.

2003-01-01

The inductively coupled plasma (ICP) is a justifiably popular source for atomic emission spectrometry. However, despite its popularity, the ICP is still only partially understood. Even the mechanisms of analyte excitation remain unclear; some energy levels are quite clearly populated by charge transfer while others might be populated by electron-ion recombination, by electron impact, or by Penning processes. Distinguishing among these alternatives is possible by means of a steady-state kinetics approach that examines correlations between the emission of a selected atom, ion, or level and the local number densities of species assumed to produce the excitation. In an earlier investigation, strong correlations were found between either calcium atom or ion emission and selected combinations of calcium atom or ion number densities and electron number densities in the plasma. However, all radially resolved data employed in the earlier study were produced from Abel inversion and from measurements that were crude by today's standards. Now, by means of tomographic imaging, laser-saturated atomic fluorescence, and Thomson and Rayleigh scattering, it is possible to measure the required radially resolved data without Abel inversion and with far greater fidelity. The correlations previously studied for calcium have been investigated with these more reliable data. Ion-electron recombination, either radiative or with argon as a third body, was determined to be the most likely excitation mechanism for calcium atom, while electron impact appeared to be the most important process to produce excite-state calcium ions. These results were consistent with the previous study. However, the present study suggests that collisional deactivation, rather than radiative decay, is the most likely mode of returning both calcium atoms and ions to the ground state

Excitation mechanism for nickel and argon lines emitted by radio-frequency glow discharge plasma associated with bias current introduction

International Nuclear Information System (INIS)

Kodama, Kenji; Wagatsuma, Kazuaki

2004-01-01

The introduction of d.c. bias current to an r.f. glow discharge plasma led to enhancement in the intensity of particular emission lines. In order to investigate the excitation mechanism, a large number of nickel emission lines was measured with and without the bias-current introduction. Emission intensities of nickel atomic lines were predominantly elevated by conducting bias current, especially when the emission lines have an excitation energy of approximately 5 eV. This phenomenon could be explained from the additional excitation through collisions with the introduced electrons having kinetic energies favorable for the excitation of such nickel atomic lines. However, this additional excitation mechanism was less effective for excited states of nickel ion, argon atom and argon ion, because their excitation energies were fairly high compared with the excitation energies of Ni atomic lines

Ultrafast photodynamics of the indoline dye D149 adsorbed to porous ZnO in dye-sensitized solar cells.

Science.gov (United States)

Rohwer, Egmont; Richter, Christoph; Heming, Nadine; Strauch, Kerstin; Litwinski, Christian; Nyokong, Tebello; Schlettwein, Derck; Schwoerer, Heinrich

2013-01-14

We investigate the ultrafast dynamics of the photoinduced electron transfer between surface-adsorbed indoline D149 dye and porous ZnO as used in the working electrodes of dye-sensitized solar cells. Transient absorption spectroscopy was conducted on the dye in solution, on solid state samples and for the latter in contact to a I(-)/I(3)(-) redox electrolyte typical for dye-sensitized solar cells to elucidate the effect of each component in the observed dynamics. D149 in a solution of 1:1 acetonitrile and tert-butyl alcohol shows excited-state lifetimes of 300±50 ps. This signature is severely quenched when D149 is adsorbed to ZnO, with the fastest component of the decay trace measured at 150±20 fs due to the charge-transfer mechanism. Absorption bands of the oxidized dye molecule were investigated to determine regeneration times which are in excess of 1 ns. The addition of the redox electrolyte to the system results in faster regeneration times, of the order of 1 ns. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Comparison of excitation mechanisms in the analytical regions of a high-power two-jet plasma

International Nuclear Information System (INIS)

Zaksas, Natalia P.

2015-01-01

Excitation mechanisms in the analytical regions of a high-power two-jet plasma were investigated. A new plasmatron recently developed was applied in this work. The Boltzmann population of excited levels of Fe atoms and ions was observed in both analytical regions, before and after the jet confluence, as well as in the jet confluence, which proves excitation of atoms and ions by electron impact. The disturbance of local thermodynamic equilibrium in all regions of the plasma flow was deduced on the basis of considerable difference in Fe atomic and ionic excitation temperatures. Such a difference is most likely to be caused by contribution of metastable argon to atom ionization. The region before the jet confluence has the greatest difference in Fe atomic and ionic excitation temperatures and is more non-equilibrium than the region after the confluence due to comparatively low electron and high metastable argon concentrations. Low electron concentration in this region provides lower background emission than in the region after the jet confluence, which leads to better detection limits for the majority of elements. - Highlights: • Excitation mechanisms were investigated in the analytical regions of a high-power TJP. • Boltzmann population of excited levels of Fe atoms and ions takes place in all regions of the plasma flow. • The considerable difference in Fe atomic and ionic excitation temperatures occurs. • Penning ionization by metastable argon results in disturbance of LTE in the plasma. • The region before the jet confluence is more non-equilibrium than after that

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.

Light particle emission as a probe of reaction mechanism and nuclear excitation

International Nuclear Information System (INIS)

Guerreau, D.

1989-01-01

The central part of these lectures will be dealing with the problem of energy dissipation. A good understanding of the mechanisms for the dissipation requires to study both peripheral and central collisions or, in other words, to look at the impact paramenter dependence. This should also provide valuable information on the time scale. In order to probe the reaction mechanism and nuclear excitation, one of the most powerful tool is unquestionably the observation of light particle emission, including neutrons and charged particles. Several examples will be discussed related to peripheral collisions (the fate of transfer reactions, the excitation energy generation, the production of projectile-like fragments) as well as inner collisions for which extensive studies have demonstrated the strength of intermediate energy heavy ions for the production of very hot nuclei and detailed study of their decay properties

Hybrid Monolith of Graphene/TEMPO-Oxidized Cellulose Nanofiber as Mechanically Robust, Highly Functional, and Recyclable Adsorbent of Methylene Blue Dye

Directory of Open Access Journals (Sweden)

Asif Hussain

2018-01-01

Full Text Available Herein we demonstrate first report on fabrication, characterization, and adsorptive appraisal of graphene/cellulose nanofibers (GO/CNFs monolith for methylene blue (MB dye. Series of hybrid monolith (GO/CNFs were assembled via urea assisted self-assembly method. Hybrid materials were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction patterns, Raman spectroscopy, elemental analysis, thermogravimetric curve analysis, specific surface area, surface charge density measurement, and compressional mechanical analysis. It was proposed that strong chemical interaction (mainly hydrogen bonding was responsible for the formation of hybrid assembly. GO/CNFs monolith showed mechanically robust architecture with tunable pore structure and surface properties. GO/CNFs adsorbent could completely remove trace to moderate concentrations of MB dye and follow pseudo-second-order kinetics model. Adsorption isotherm behaviors were found in the following order: Langmuir isotherm > Freundlich isotherm > Temkin isotherm model. Maximum adsorption capacity of 227.27 mg g−1 was achieved which is much higher than reported graphene based monoliths and magnetic adsorbent. Incorporation of nanocellulose follows exponential relationship with dye uptake capacities. High surface charge density and specific surface area were main dye adsorptive mechanism. Regeneration and recycling efficiency was achieved up to four consecutive cycles with cost-effective recollection and zero recontamination of treated water.

SAPO-34 coated adsorbent heat exchanger for adsorption chillers

International Nuclear Information System (INIS)

Freni, Angelo; Bonaccorsi, Lucio; Calabrese, Luigi; Caprì, Angela; Frazzica, Andrea; Sapienza, Alessio

2015-01-01

In this work, adsorbent coatings on aluminum surfaces were prepared by dip-coating method starting from a water suspension of SAPO-34 zeolite and a silane-based binder. Silane-zeolite coatings morphology and surface coverage grade were evaluated by scanning electron microscopy. Adhesive and mechanical properties were evaluated by peel, pull-off, impact and micro-hardness tests, confirming the good interaction between metal substrate, binder and zeolite. Adsorption equilibrium and kinetics of water vapour adsorption on the adsorbent coating were studied in the range T = 30–150 °C and pH 2 O = 11 mbar using a CAHN 2000 thermo-balance. It was found that, in the investigated conditions, the organic binder doesn't affect the water adsorption capacity and adsorption kinetics of the original SAPO-34 zeolite. Subsequently, the zeolite coating was applied on a finned flat-tubes aluminum heat exchanger realizing a full-scale AdHEx with an uniform adsorbent coating 0.1 mm thick and a metal/adsorbent mass ratio = 6. The cooling capacity of the realized coated AdHEx was measured by a lab-scale adsorption chiller under realistic operating conditions for air conditioning applications. The coated AdHEx produced up to 675 W/kg ads specific cooling power with a cycle time of 5 min. Adsorption stability of the coated adsorber subjected to 600 sorption cycles was successfully verified. - Highlights: • Adsorbent coatings on aluminum surfaces were prepared by dip-coating method. • Silane-zeolite coatings morphology, and mechanical properties were studied. • The zeolite coating was applied on a finned flat-tubes aluminum heat exchanger. • The coated AdHEx was tested in a lab scale adsorption chiller

The mechanism of three-body process of energy transfer from excited xenon atoms to molecules

International Nuclear Information System (INIS)

Wojciechowski, K.; Forys, M.

1999-01-01

The mechanism of energy transfer from Xe(6 s[3/2] 1 ) resonance state (E=8.44 eV) and higher excited Xe(6p, 6p', 6 d) atoms produced in pulse radiolysis to molecules have been discussed. The analysis of the kinetic data for these processes shows that in the sensitized photolysis and radiolysis of Xe-M mixtures the excited atoms decay in 'ordinary' two-body reaction: Xe(6s[3/2] 1 0 )+M→products (r.1) and in fast 'accelerated' third order process: Xe(6s[3/2] 1 0 )+M+Xe→products (r.2) The discussion shows that three-body process occurs via reactions: Xe(6s[3/2] 1 0 )+Xe k w ↔ k d Xe 2 ** (r.2a) Xe 2 **+M k q →[Xe 2 M]*→products (r.2b) It was shown that this mechanism concerns also higher excited Xe atoms and can explain a similar process in He-M mixtures and suggests that it is a general mechanism of energy transfer in all irradiated rare gas-molecule systems

Simulation of spatially dependent excitation rates and power deposition in RF discharges for plasma processing

International Nuclear Information System (INIS)

Kushner, M.J.; Anderson, H.M.; Hargis, P.J.

1985-01-01

In low pressure, radio frequency (RF) discharges of the type used in plasma processing of semiconductor materials, the rate of electron impact excitation and energy transfer processes depends upon both the phase of the RF excitation and position in the discharge. Electron impact collisions create radicals that diffuse or drift to the surfaces of interest where they are adsorbed or otherwise react. To the extent that these radicals have a finite lifetime, their transport time from point of creation to surface of interest is an important parameter. The spatial dependence of the rate of the initial electron impact collisions is therefore also an important parameter. The power that sustains the discharge is coupled into the system by two mechanisms: a high energy e-beam component of the electron distribution resulting from electrons falling through or being accelerated by the sheaths, and by joule heating in the body of the plasma. In this paper, the authors discuss the spatial dependence of excitation rates and the method of power deposition iin RF discharges of the type used for plasma processing

Nuclear quantum effects on the nonadiabatic decay mechanism of an excited hydrated electron

Science.gov (United States)

Borgis, Daniel; Rossky, Peter J.; Turi, László

2007-11-01

We present a kinetic analysis of the nonadiabatic decay mechanism of an excited state hydrated electron to the ground state. The theoretical treatment is based on a quantized, gap dependent golden rule rate constant formula which describes the nonadiabatic transition rate between two quantum states. The rate formula is expressed in terms of quantum time correlation functions of the energy gap and of the nonadiabatic coupling. These gap dependent quantities are evaluated from three different sets of mixed quantum-classical molecular dynamics simulations of a hydrated electron equilibrated (a) in its ground state, (b) in its first excited state, and (c) on a hypothetical mixed potential energy surface which is the average of the ground and the first excited electronic states. The quantized, gap dependent rate results are applied in a phenomenological kinetic equation which provides the survival probability function of the excited state electron. Although the lifetime of the equilibrated excited state electron is computed to be very short (well under 100fs), the survival probability function for the nonequilibrium process in pump-probe experiments yields an effective excited state lifetime of around 300fs, a value that is consistent with the findings of several experimental groups and previous theoretical estimates.

Investigation of Sterilization Mechanism for Geobacillus stearothermophilus Spores with Plasma-Excited Neutral Gas

Science.gov (United States)

Matsui, Kei; Ikenaga, Noriaki; Sakudo, Noriyuki

2015-09-01

We investigate the mechanism of the sterilization with plasma-excited neutral gas that uniformly sterilizes both the space and inner wall of the reactor chamber at atmospheric pressure. Only reactive neutral species such as plasma-excited gas molecules and radicals are separated from the plasma and sent to the reactor chamber for chemical sterilization. The plasma source gas uses humidified mixture of nitrogen and oxygen. Geobacillus stearothermophilus spores and tyrosine which is amino acid are treated by the plasma-excited neutral gas. Shape change of the treated spore is observed by SEM, and chemical modification of the treated tyrosine is analyzed by HPLC. As a result, the surface of the treated spore shows depression. Hydroxylation and nitration of tyrosine are shown after the treatment. For these reasons, we believe that the sterilization with plasma-excited neutral gas results from the deformation of spore structure due to the chemical modification of amino acid.

First-principles study of pollutant molecules absorbed on polymeric adsorbents using the vdW-DF2 functional

Science.gov (United States)

Zhu, Jinguo; Wang, Yapeng; Tian, Ting; Zhang, Qianfan

2018-03-01

Polymeric adsorbents have been attracting increasing attention because of their favorable structrual properties and effectiveness of solving small molecules contaminants. However, due to the absence of deep insight into the adsorption mechanism of polymeric adsorbents, researches on new polymeric adsorbents can only be carried out by repeated experiments and tests, which is extremely inefficient. Therefore, investigating the adsorption process of polymeric adsorbents, especially the mechanism of adsorbing various air pollutant molecules by materials modelling and simulation, is of great significance. Here in this work, we systematically studied the adsorption mechanism by first-principles computation with van der Waals interaction. It demonstrates that the adsorption between them was pure physisorption originating from the hydrogen bond and intermolecular forces consisting of Keesom force, Debye force and London dispersion force. The proportions of these forces varied according to different adsorption systems. The adsorption effects were determined by the polymers’ dipole moment and polarizability. The adsorption performance of some polymers with special structures was also investigated to explore their possibility as potential adsorbents. The results of our simulation can provide some guidance for developing new polymeric adsorbents with better performance.

In situ investigation of the mechanisms of the transport to tissues of polycyclic aromatic hydrocarbons adsorbed onto the root surface of Kandelia obovata seedlings

International Nuclear Information System (INIS)

Li, Ruilong; Zhu, Yaxian; Zhang, Yong

2015-01-01

A novel method for in situ determination of the polycyclic aromatic hydrocarbons (PAHs) adsorbed onto the root surface of Kandelia obovata seedlings was established using laser-induced time-resolved nanosecond fluorescence spectroscopy (LITRF). The linear dynamic ranges for the established method were 1.5–1240 ng/spot for phenanthrene, 1.0–1360 ng/spot for pyrene and 5.0–1220 ng/spot for benzo[a]pyrene. Then, the mechanisms of PAHs transport from the Ko root surface to tissues were investigated. The three-phase model including fast, slow and very slow fractions was superior to the single or dual-phase model to describe the PAHs transport processes. Moreover, the fast fraction of PAHs transport process was mainly due to passive movement, while the slow and very slow fractions were not. Passive movement was the main process of B[a]P adsorbed onto Ko root surface transport to tissues. In addition, the extent of the PAHs transport to Ko root tissues at different salinity were evaluated. - Highlights: • A novel method in situ determination PAHs adsorbed onto root surface was established. • The mechanisms of PAHs transport from root surface to tissues are investigated. • Passive movement is the main process of B[a]P transport from root surface to tissues. • Effects of salinity on the PAHs transport from root surface to tissues are evaluated. - Passive movement for the PAHs adsorbed onto Kandelia obovata root surface to tissues was observed by a newly established in situ LITRF method

Equilibrium and heat of adsorption of diethyl phthalate on heterogeneous adsorbents

Energy Technology Data Exchange (ETDEWEB)

Zhang, W.M.; Xu, Z.W.; Pan, B.C.; Hong, C.H.; Jia, K.; Jiang, P.J.; Zhang, Q.J.; Pan, B.J. [Nanjing University, Nanjing (China)

2008-09-15

Removal of phthalate esters from water has been of considerable concern recently. In the present study, the adsorptive removal performance of diethyl phthalate (DEP) from water was investigated with the aminated polystyrene resin (NDA-101) and oxidized polystyrene resin (NDA-702). In addition, the commercial homogeneous polystyrene resin (XAD-4) and acrylic ester resin (Amberlite XAD-7) as well as coal-based granular activated carbon (AC-750) were chosen for comparison. The corresponding equilibrium isotherms are well described by the Freundlich equation and the adsorption capacities for DEP followed the order NDA-702 > NDA-101 > AC-750 > XAD-4 > XAD-7. Analysis of adsorption mechanisms suggested that these adsorbents spontaneously adsorb DEP molecules driven mainly by enthalpy change, and the adsorption process was derived by multiple adsorbent-adsorbate interactions such as hydrogen bonding, {pi}-{pi} stacking, and micropore filling. The information related to the adsorbent surface heterogeneity and the adsorbate-adsorbate interaction was obtained by Do's model. All the results indicate that heterogeneous resins NDA-702 and NDA-101 have excellent potential as an adsorption material for the removal of DEP from the contaminated water.

Adsorbed Polymer Nanolayers on Solids: Mechanism, Structure and Applications

Science.gov (United States)

Sen, Mani Kuntal

In this thesis, by combining various advanced x-ray scattering, spectroscopic and other surface sensitive characterization techniques, I report the equilibrium polymer chain conformations, structures, dynamics and properties of polymeric materials at the solid-polymer melt interfaces. Following the introduction, in chapter 2, I highlight that the backbone chains (constituted of CH and CH2 groups) of the flattened polystyrene (PS) chains preferentially orient normal to the weakly interactive substrate surface via thermal annealing regardless of the initial chain conformations, while the orientation of the phenyl rings becomes randomized, thereby increasing the number of surface-segmental contacts (i.e., enthalpic gain) which is the driving force for the flattening process of the polymer chains even onto a weakly interactive solid. In chapter 3, I elucidate the flattened structures in block copolymer (BCP) thin films where both blocks lie flat on the substrate, forming a 2D randomly phase-separated structure irrespective of their microdomain structures and interfacial energetics. In chapter 4, I reveal the presence of an irreversibly adsorbed BCP layer which showed suppressed dynamics even at temperatures far above the individual glass transition temperatures of the blocks. Furthermore, this adsorbed BCP layer plays a crucial role in controlling the microdomain orientation in the entire film. In chapter 5, I report a radically new paradigm of designing a polymeric coating layer of a few nanometers thick ("polymer nanolayer") with anti-biofouling properties.

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.

Modulation of Corticospinal Excitability Depends on the Pattern of Mechanical Tactile Stimulation

Directory of Open Access Journals (Sweden)

Sho Kojima

2018-01-01

Full Text Available We investigated the effects of different patterns of mechanical tactile stimulation (MS on corticospinal excitability by measuring the motor-evoked potential (MEP. This was a single-blind study that included nineteen healthy subjects. MS was applied for 20 min to the right index finger. MS intervention was defined as simple, lateral, rubbing, vertical, or random. Simple intervention stimulated the entire finger pad at the same time. Lateral intervention stimulated with moving between left and right on the finger pad. Rubbing intervention stimulated with moving the stimulus probe, fixed by protrusion pins. Vertical intervention stimulated with moving in the forward and backward directions on the finger pad. Random intervention stimulated to finger pad with either row protrudes. MEPs were measured in the first dorsal interosseous muscle to transcranial magnetic stimulation of the left motor cortex before, immediately after, and 5–20 min after intervention. Following simple intervention, MEP amplitudes were significantly smaller than preintervention, indicating depression of corticospinal excitability. Following lateral, rubbing, and vertical intervention, MEP amplitudes were significantly larger than preintervention, indicating facilitation of corticospinal excitability. The modulation of corticospinal excitability depends on MS patterns. These results contribute to knowledge regarding the use of MS as a neurorehabilitation tool to neurological disorder.

Modulation of Corticospinal Excitability Depends on the Pattern of Mechanical Tactile Stimulation.

Science.gov (United States)

Kojima, Sho; Onishi, Hideaki; Miyaguchi, Shota; Kotan, Shinichi; Sasaki, Ryoki; Nakagawa, Masaki; Kirimoto, Hikari; Tamaki, Hiroyuki

2018-01-01

We investigated the effects of different patterns of mechanical tactile stimulation (MS) on corticospinal excitability by measuring the motor-evoked potential (MEP). This was a single-blind study that included nineteen healthy subjects. MS was applied for 20 min to the right index finger. MS intervention was defined as simple, lateral, rubbing, vertical, or random. Simple intervention stimulated the entire finger pad at the same time. Lateral intervention stimulated with moving between left and right on the finger pad. Rubbing intervention stimulated with moving the stimulus probe, fixed by protrusion pins. Vertical intervention stimulated with moving in the forward and backward directions on the finger pad. Random intervention stimulated to finger pad with either row protrudes. MEPs were measured in the first dorsal interosseous muscle to transcranial magnetic stimulation of the left motor cortex before, immediately after, and 5-20 min after intervention. Following simple intervention, MEP amplitudes were significantly smaller than preintervention, indicating depression of corticospinal excitability. Following lateral, rubbing, and vertical intervention, MEP amplitudes were significantly larger than preintervention, indicating facilitation of corticospinal excitability. The modulation of corticospinal excitability depends on MS patterns. These results contribute to knowledge regarding the use of MS as a neurorehabilitation tool to neurological disorder.

Excitation of solar and stellar oscillations

International Nuclear Information System (INIS)

Baudin, Frederic

2009-01-01

In this report for an Accreditation to Supervise Research (HDR), and after an introduction which outlines the potential of helio-seismology, the author addresses the problem of excitation and amplitude of stellar oscillations with respect to their most important aspects, i.e. the theoretical framework of the present understanding of excitation mechanisms, and instrumental influences on measurements which are used to assess excitation rates, the difficulty to perform these measurements, and their analysis in some various cases. Thus, the author addresses excitation mechanisms of stellar oscillation (stochastic excitation, opacity- related excitation, and other excitation mechanisms), the excitation of solar modes (observation and theoretical predictions, influence of magnetic phenomena, solar g modes), and the excitation of modes in other stars (solar-type pulsators, red giants, and not so conventional pulsators such as HD180642 and Be stars like HD49330)

Dual frequency parametric excitation of a nonlinear, multi degree of freedom mechanical amplifier with electronically modified topology

Science.gov (United States)

Dolev, A.; Bucher, I.

2018-04-01

Mechanical or electromechanical amplifiers can exploit the high-Q and low noise features of mechanical resonance, in particular when parametric excitation is employed. Multi-frequency parametric excitation introduces tunability and is able to project weak input signals on a selected resonance. The present paper addresses multi degree of freedom mechanical amplifiers or resonators whose analysis and features require treatment of the spatial as well as temporal behavior. In some cases, virtual electronic coupling can alter the given topology of the resonator to better amplify specific inputs. An analytical development is followed by a numerical and experimental sensitivity and performance verifications, illustrating the advantages and disadvantages of such topologies.

Inelastic scattering of 9Li and excitation mechanism of its first excited state

International Nuclear Information System (INIS)

Al Falou, H.; Kanungo, R.; Andreoiu, C.; Cross, D.S.; Davids, B.; Djongolov, M.; Gallant, A.T.; Galinski, N.; Howell, D.; Kshetri, R.; Niamir, D.; Orce, J.N.; Shotter, A.C.; Sjue, S.; Tanihata, I.; Thompson, I.J.; Triambak, S.; Uchida, M.; Walden, P.; Wiringa, R.B.

2013-01-01

The first measurement of inelastic scattering of 9 Li from deuterons at the ISAC facility is reported. The measured angular distribution for the first excited state confirms the nature of excitation to be an E2 transition. The quadrupole deformation parameter is extracted from an analysis of the angular distribution

Orientational epitaxy in adsorbed monolayers

International Nuclear Information System (INIS)

Novaco, A.D.; McTague, J.P.

1977-01-01

The ground state for adsorbed monolayers on crystalline substrates is shown to involve a definite relative orientation of the substrate and adsorbate crystal axes, even when the relative lattice parameters are incommensurate. The rotation angle which defines the structure of the monolayer-substrate system is determined by the competition between adsorbate-substrate and adsorbate-adsorbate energy terms, and is generally not a symmetry angle. Numerical predictions are presented for the rare gas-graphite systems, whose interaction potentials are rather well known. Recent LEED data for some of these systems appear to corroborate these predictions

Facile preparation of salt-tolerant anion-exchange membrane adsorber using hydrophobic membrane as substrate.

Science.gov (United States)

Fan, Jinxin; Luo, Jianquan; Chen, Xiangrong; Wan, Yinhua

2017-03-24

In this study, a polyvinylidene fluoride (PVDF) hydrophobic membrane with high mechanical property was used as substrate to prepare salt-tolerant anion-exchange (STAE) membrane adsorber. Effective hydrophilization and functionalization of PVDF membrane was realized via polydopamine (PDA) deposition, thus overcoming the drawbacks of hydrophobic substrates including poor water permeability, inert property as well as severe non-specific adsorption. The following polyallylamine (PAH) coupling was carried out at pH 10.0, where unprotonated amine groups on PAH chains were more prone to couple with PDA. This membrane adsorber could remain 75% of protein binding capacity when NaCl concentration increased from 0 to 150mM, while its protein binding capacity was independent of flow rate from 10 to 100 membrane volume (MV)/min due to its high mechanical strength (tensile strength: 43.58±2.30MPa). With 200mM NaCl addition at pH 7.5, high purity (above 99%) and high recovery (almost 100%) of Immunoglobulin G (IgG) were obtained when using the STAE membrane adsorber to separate IgG/human serum albumin (HSA) mixture, being similar to that without NaCl at pH 6.0 (both under the flow rate of 10-100MV/min). Finally, the reliable reusability was confirmed by five reuse cycles of protein binding and elution operations. In comparison with commercial membrane adsorber, the new membrane adsorber exhibited a better mechanical property, higher IgG polishing efficiency and reusability, while the protein binding capacity was lower due to less NH 2 density on the membrane. The outcome of this work not only offers a facile and effective approach to prepare membrane adsorbers based on hydrophobic membranes, but also demonstrates great potential of this new designed STAE membrane adsorbers for efficient monoclonal antibody (mAb) polishing. Copyright © 2017 Elsevier B.V. All rights reserved.

Numerical Study on the Contribution of Convective Mass Transfer Inside High-Porosity Adsorbents in the VOC Adsorption Process

DEFF Research Database (Denmark)

Zhang, Ge; He, Wenna; Fang, Lei

2013-01-01

The transfer mechanism of volatile organic compounds (VOCs) being trapped inside the various types of adsorbents is usually regarded as mere diffusion. This paper investigated the contribution of convective mass transfer inside the adsorbents used for VOC air-cleaning. The adsorbents are typically...

The adsorber loop concept for the contact between seawater and adsorber granulate

International Nuclear Information System (INIS)

Koske, P.H.; Ohlrogge, K.

1984-01-01

For the production of 1 kg uranium from seawater about 10 9 kg seawater - depending on the extraction efficiency - have to be processed in a production plant. Such high seawater flows have to be put through adsorber beds the area of which depends on the flow velocity of the water in the bed. For a typical polyamidoxim (PAO) adsorber granulate with a grain size distribution of 0.3 to 1.2 mm the velocity in a fluidized bed is limited to about 1 cm/s in order to prevent carry out of the adsorber material. The consequences of this rather low bed velocity are large and expensive bed areas for technical production plants. The present paper deals with the so-called ''adsorber loop concept'' in which the adsorber granulate is carried along with the seawater to be processed in a loop-like configuration and is separated again from the water before this is leaving the adsorption unit. This concept enables considerably higher seawater velocities thus reducing the bed area. Theoretical considerations are presented together with experimental results from field tests. (author)

Waste Material Adsorbents for Zinc Removal from Wastewater: A Comprehensive Review

Directory of Open Access Journals (Sweden)

Haider M. Zwain

2014-01-01

Full Text Available This review examines a variety of adsorbents and discusses mechanisms, modification methods, recovery and regeneration, and commercial applications. A summary of available researches has been composed by a wide range of potentially low-cost modified adsorbents including activated carbon, natural source adsorbents (clay, bentonite, zeolite, etc., biosorbents (black gram husk, sugar-beet pectin gels, citrus peels, banana and orange peels, carrot residues, cassava waste, algae, algal, marine green macroalgae, etc., and byproduct adsorbents (sawdust, lignin, rice husk, rice husk ash, coal fly ash, etc.. From the literature survey, different adsorbents were compared in terms of Zn2+ adsorption capacity; also Zn2+ adsorption capacity was compared with other metals adsorption. Thus, some of the highest adsorption capacities reported for Zn2+ are 168 mg/g powdered waste sludge, 128.8 mg/g dried marine green macroalgae, 73.2 mg/g lignin, 55.82 mg/g cassava waste, and 52.91 mg/g bentonite. Furthermore, modification of adsorbents can improve adsorption capacity. Regeneration cost is important, but if consumption of virgin adsorbent is reduced, then multiple economic, industrial, and environmental benefits can be gained. Finally, the main drawback of the already published Zn2+ adsorption researches is that their use is still in the laboratory stage mostly without scale-up, pilot studies, or commercialization.

Pharmacological approach to the mechanisms of transcranial DC-stimulation-induced after-effects of human motor cortex excitability.

Science.gov (United States)

Liebetanz, David; Nitsche, Michael A; Tergau, Frithjof; Paulus, Walter

2002-10-01

Weak transcranial direct current stimulation (tDCS) induces persisting excitability changes in the human motor cortex. These plastic excitability changes are selectively controlled by the polarity, duration and current strength of stimulation. To reveal the underlying mechanisms of direct current (DC)-induced neuroplasticity, we combined tDCS of the motor cortex with the application of Na(+)-channel-blocking carbamazepine (CBZ) and the N-methyl-D-aspartate (NMDA)-receptor antagonist dextromethorphan (DMO). Monitored by transcranial magnetic stimulation (TMS), motor cortical excitability changes of up to 40% were achieved in the drug-free condition. Increase of cortical excitability could be selected by anodal stimulation, and decrease by cathodal stimulation. Both types of excitability change lasted several minutes after cessation of current stimulation. DMO suppressed the post-stimulation effects of both anodal and cathodal DC stimulation, strongly suggesting the involvement of NMDA receptors in both types of DC-induced neuroplasticity. In contrast, CBZ selectively eliminated anodal effects. Since CBZ stabilizes the membrane potential voltage-dependently, the results reveal that after-effects of anodal tDCS require a depolarization of membrane potentials. Similar to the induction of established types of short- or long-term neuroplasticity, a combination of glutamatergic and membrane mechanisms is necessary to induce the after-effects of tDCS. On the basis of these results, we suggest that polarity-driven alterations of resting membrane potentials represent the crucial mechanisms of the DC-induced after-effects, leading to both an alteration of spontaneous discharge rates and to a change in NMDA-receptor activation.

Modal Testing of Mechanical Structures Subject to Operational Excitation Forces

DEFF Research Database (Denmark)

Møller, N.; Brincker, Rune; Herlufsen, H.

2000-01-01

to the Operational Modal Analysis. For Operational Modal Analysis two different estimation techniques are used: a non-parametric technique based on Frequency Domain Decomposition (FDD), and a parametric technique working on the raw data in time domain, a data driven Stochastic Subspace Identification (SSI) algorithm......Operational Modal Analysis also known as Output Only Modal Analysis has in the recent years been used for extracting modal parameters of civil engineering structures and is now becoming popular for mechanical structures. The advantage of the method is that no artificial excitation need...

Sulfur removal from fuel using zeolites/polyimide mixed matrix membrane adsorbents

International Nuclear Information System (INIS)

Lin, Ligang; Wang, Andong; Dong, Meimei; Zhang, Yuzhong; He, Benqiao; Li, Hong

2012-01-01

Graphical abstract: Membrane adsorption process is proposed for sulfur removal. Three-dimensional network structure is key to fulfill adsorption function of MMMs, which adsorption/desorption behavior is markedly related with binding force with sulfur molecules. Highlights: ► Membrane adsorption process is proposed for sulfur removal. ► Three-dimensional network structure of MMMs is key to fulfill adsorption function. ► Adsorption/desorption behavior is markedly related with binding force. - Abstract: A novel membrane adsorption process was proposed for the sulfur removal from fuels. The mixed matrix membranes (MMMs) adsorbents composed of polyimide (PI) and various Y zeolites were prepared. By the detailed characterization of FT-IR, morphology, thermal and mechanical properties of MMMs adsorbents, combining the adsorption and desorption behavior research, the process–structure–function relationship was discussed. Field-emission scanning electron microscope (FESEM) images show that the functional particles are incorporated into the three-dimensional network structure. MMMs adsorbents with 40% of zeolites content possess better physical properties, which was confirmed by mechanical strength and thermo stability analysis. Influence factors including post-treatment, content of incorporated zeolites, adsorption time, temperature, initial sulfur concentration as well as sulfur species on the adsorption performance of MMMs adsorbents have been evaluated. At 4 wt.% zeolites content, adsorption capacity for NaY/PI, AgY/PI and CeY/PI MMMs adsorbents come to 2.0, 7.5 and 7.9 mg S/g, respectively. And the regeneration results suggest that the corresponding spent membranes can recover about 98%, 90% and 70% of the desulfurization capacity, respectively. The distinct adsorption and desorption behavior of MMMs adsorbents with various functional zeolites was markedly related with their various binding force and binding mode with sulfur compounds.

Shock compression and flash-heating of molecular adsorbates on the picosecond time scale

Science.gov (United States)

Berg, Christopher Michael

An ultrafast nonlinear coherent laser spectroscopy termed broadband multiplex vibrational sum-frequency generation (SFG) with nonresonant suppression was employed to monitor vibrational transitions of molecular adsorbates on metallic substrates during laser-driven shock compression and flash-heating. Adsorbates were in the form of well-ordered self-assembled monolayers (SAMs) and included molecular explosive simulants, such as nitroaromatics, and long chain-length alkanethiols. Based on reflectance measurements of the metallic substrates, femtosecond flash-heating pulses were capable of producing large-amplitude temperature jumps with DeltaT = 500 K. Laser-driven shock compression of SAMs produced pressures up to 2 GPa, where 1 GPa ≈ 1 x 104 atm. Shock pressures were estimated via comparison with frequency shifts observed in the monolayer vibrational transitions during hydrostatic pressure measurements in a SiC anvil cell. Molecular dynamics during flash-heating and shock loading were probed with vibrational SFG spectroscopy with picosecond temporal resolution and sub-nanometer spatial resolution. Flash-heating studies of 4-nitrobenzenethiolate (NBT) on Au provided insight into effects from hot-electron excitation of the molecular adsorbates at early pump-probe delay times. At longer delay times, effects from the excitation of SAM lattice modes and lower-energy NBT vibrations were shown. In addition, flash-heating studies of alkanethiolates demonstrated chain disordering behaviors as well as interface thermal conductances across the Au-SAM junction, which was of specific interest within the context of molecular electronics. Shock compression studies of molecular explosive simulants, such as 4-nitrobenzoate (NBA), demonstrated the proficiency of this technique to observe shock-induced molecular dynamics, in this case orientational dynamics, on the picosecond time scale. Results validated the utilization of these refined shock loading techniques to probe the shock

海藻酸镧颗粒除氟研究：吸附剂物性和吸附机理%Fluoride Removal by Lanthanum Alginate Bead:Adsorbent Characterization and Adsorption Mechanism

Institute of Scientific and Technical Information of China (English)

霍亚坤; 丁文明; 黄霞; 徐静年; 赵梦华

2011-01-01

Lanthanum alginate bead is a new, highly active adsorbent. In the present study, we investigated its adsorption performance and its adsorption mechanism. The adsorption isotherm for fluoride onto lanthanum alginate bead fits the Langmuir model well, and the maximum adsorption capacity is 197.2 mg·g-1. X-ray diffraction shows the amorphous nature of lanthanum alginate bead, which allows for better accessibility to fluoride and thus better activity. Infrared spectra of lanthanum alginate bead before and after adsorption confirm its stable skeletal structure.Scanning electron microscopy shows that the dense surface structure of the adsorbent appear cracks after adsorption.The adsorption mechanism of lanthanum alginate bead is considered as an ion exchange between F- and Cl- or OH-,as verified from the adsorbent and the solution by pH effect, energy dispersive X-ray, and ion chromatography.

Mechanism of occurrence of self-exciting sloshing in rectangular vessel by plane jet flow

International Nuclear Information System (INIS)

Fukaya, Masashi; Okamoto, Koji; Madarame, Haruki

1996-01-01

FBRs have free liquid surfaces in reactor vessels and others, and it is expected that the flow velocity of liquid sodium coolant heightens accompanying the reduction of the reactor size. In the field where free liquid surface and high velocity flow exist, there is the possibility that various unstable phenomena occur on the liquid surface by the interference of the free liquid surface and flow. One example is the self-exciting sloshing by flow. In order to elucidate the mechanism of occurrence of the phenomena in a simple system, the experimental and analytical examinations were carried out on the self-exciting sloshing of free liquid surface in a rectangular vessel by plane jet flow. The basic oscillation characteristics of self-exciting sloshing were examined, and the physical quantities that control the occurrence of self-exciting sloshing were investigated by examining the effect in the case of changing the shapes of vessels. The experiments on the self-exciting sloshing in the case of vertical, horizontal and oblique plane jet flows are reported. The model for the occurrence of oscillation, in which the interaction of sloshing and jet variation was simplified, is proposed, and the verification of the model is reported. (K.I.)

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.

Boltzmann statistical consideration on the excitation mechanism of iron atomic lines emitted from glow discharge plasmas

International Nuclear Information System (INIS)

Zhang Lei; Kashiwakura, Shunsuke; Wagatsuma, Kazuaki

2011-01-01

A Boltzmann plot for many iron atomic lines having excitation energies of 3.3–6.9 eV was investigated in glow discharge plasmas when argon or neon was employed as the plasma gas. The plot did not show a linear relationship over a wide range of the excitation energy, but showed that the emission lines having higher excitation energies largely deviated from a normal Boltzmann distribution whereas those having low excitation energies (3.3–4.3 eV) well followed it. This result would be derived from an overpopulation among the corresponding energy levels. A probable reason for this is that excitations for the high-lying excited levels would be caused predominantly through a Penning-type collision with the metastable atom of argon or neon, followed by recombination with an electron and then stepwise de-excitations which can populate the excited energy levels just below the ionization limit of iron atom. The non-thermal excitation occurred more actively in the argon plasma rather than the neon plasma, because of a difference in the number density between the argon and the neon metastables. The Boltzmann plots yields important information on the reason why lots of Fe I lines assigned to high-lying excited levels can be emitted from glow discharge plasmas. - Highlights: ► This paper shows the excitation mechanism of Fe I lines from a glow discharge plasma. ► A Boltzmann distribution is studied among iron lines of various excitation levels. ► We find an overpopulation of the high-lying energy levels from the normal distribution. ► It is caused through Penning-type collision of iron atom with argon metastable atom.

Photoconductivities from band states and a dissipative electron dynamics: Si(111) without and with adsorbed Ag clusters

International Nuclear Information System (INIS)

Vazhappilly, Tijo; Hembree, Robert H.; Micha, David A.

2016-01-01

A new general computational procedure is presented to obtain photoconductivities starting from atomic structures, combining ab initio electronic energy band states with populations from density matrix theory, and implemented for a specific set of materials based on Si crystalline slabs and their nanostructured surfaces without and with adsorbed Ag clusters. The procedure accounts for charge mobility in semiconductors in photoexcited states, and specifically electron and hole photomobilities at Si(111) surfaces with and without adsorbed Ag clusters using ab initio energy bands and orbitals generated from a generalized gradient functional, however with excited energy levels modified to provide correct bandgaps. Photoexcited state populations for each band and carrier type were generated using steady state solution of a reduced density matrix which includes dissipative medium effects. The present calculations provide photoexcited electronic populations and photoinduced mobilities resulting from applied electric fields and obtained from the change of driven electron energies with their electronic momentum. Extensive results for Si slabs with 8 layers, without and with adsorbed Ag clusters, show that the metal adsorbates lead to substantial increases in the photomobility and photoconductivity of electrons and holes

Aging assessment of nuclear air-treatment system HEPA filters and adsorbers

International Nuclear Information System (INIS)

Winegardner, W.K.

1993-08-01

A Phase I aging assessment of high-efficiency particulate air (HEPA) filters and activated carbon gas adsorption units (adsorbers) was performed by the Pacific Northwest Laboratory (PNL) as part of the US Nuclear Regulatory Commission's (NRC) Nuclear Plant Aging Research (NPAR) Program. Information concerning design features; failure experience; aging mechanisms, effects, and stressors; and surveillance and monitoring methods for these key air-treatment system components was compiled. Over 1100 failures, or 12 percent of the filter installations, were reported as part of a Department of Energy (DOE) survey. Investigators from other national laboratories have suggested that aging effects could have contributed to over 80 percent of these failures. Tensile strength tests on aged filter media specimens indicated a decrease in strength. Filter aging mechanisms range from those associated with particle loading to reactions that alter properties of sealants and gaskets. Low radioiodine decontamination factors associated with the Three Mile Island (TMI) accident were attributed to the premature aging of the carbon in the adsorbers. Mechanisms that can lead to impaired adsorber performance include oxidation as well as the loss of potentially available active sites as a result of the adsorption of pollutants. Stressors include heat, moisture, radiation, and airborne particles and contaminants

Inelastic scattering of {sup 9}Li and excitation mechanism of its first excited state

Energy Technology Data Exchange (ETDEWEB)

Al Falou, H. [Astronomy and Physics Department, Saint Mary' s University, Halifax, Nova Scotia B3H 3C3 (Canada); TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Kanungo, R., E-mail: ritu@triumf.ca [Astronomy and Physics Department, Saint Mary' s University, Halifax, Nova Scotia B3H 3C3 (Canada); Andreoiu, C.; Cross, D.S. [Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6 (Canada); Davids, B.; Djongolov, M. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Gallant, A.T. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Department of Physics, University of British Columbia, British Columbia V6T 1Z4 (Canada); Galinski, N.; Howell, D. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6 (Canada); Kshetri, R.; Niamir, D. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Orce, J.N. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Department of Physics, University of the Western Cape, P/B X17, Bellville, ZA-7535 (South Africa); Shotter, A.C. [Department of Physics and Astronomy, University of Edinburgh, Edinburgh (United Kingdom); Sjue, S. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Tanihata, I. [Research Center for Nuclear Physics, Osaka University, Mihogaoka, Ibaraki, Osaka 567 0047 (Japan); Thompson, I.J. [Lawrence Livermore National Laboratory, Livermore, CA 94551 (United States); Triambak, S. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Uchida, M. [Astronomy and Physics Department, Saint Mary' s University, Halifax, Nova Scotia B3H 3C3 (Canada); Walden, P. [TRIUMF, Vancouver, British Columbia V6T 2A3 (Canada); Wiringa, R.B. [Physics Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

2013-04-25

The first measurement of inelastic scattering of {sup 9}Li from deuterons at the ISAC facility is reported. The measured angular distribution for the first excited state confirms the nature of excitation to be an E2 transition. The quadrupole deformation parameter is extracted from an analysis of the angular distribution.

Surface-enhanced raman spectroscopy of quinomethionate adsorbed on silver colloids

International Nuclear Information System (INIS)

Kim, Mak Soon; Kang, Jae Soo; Park, Si Bum; Lee, Mu Sang

2003-01-01

We have studied the surface-enhanced Raman spectroscopy (SERS) spectrum of quinomethionate (6-methyl-1,3-dithiolo(4,5-b)quinoxalin-2-one), which is an insecticide or fungicide used on vegetables and wheat. We observed no signals in the ordinary Raman spectra of solid-state quinomethionate, but when it was adsorbed on a colloidal silver surface, strong vibrational signals were obtained at a very low concentration. The SERS spectra were obtained by silver colloids prepared by the Creighton et al. method. The influence of pH and the aggregation inductors (Cl - , Br - , I - , F - ) on the adsorption mechanism was investigated. Two different adsorption mechanisms were deduced, depending on the experimental conditions: The one N atom or two N atoms are chemisorbed on an Ag surface. An important contribution of the chemical mechanism was inferred when the one N atom was perpendicularly adsorbed on a surface. It is possible that quinomethionate can be detected to about 10 -5 M

Boltzmann statistical consideration on the excitation mechanism of iron atomic lines emitted from glow discharge plasmas

Energy Technology Data Exchange (ETDEWEB)

Zhang Lei; Kashiwakura, Shunsuke; Wagatsuma, Kazuaki, E-mail: wagatuma@imr.tohoku.ac.jp

2011-11-15

A Boltzmann plot for many iron atomic lines having excitation energies of 3.3-6.9 eV was investigated in glow discharge plasmas when argon or neon was employed as the plasma gas. The plot did not show a linear relationship over a wide range of the excitation energy, but showed that the emission lines having higher excitation energies largely deviated from a normal Boltzmann distribution whereas those having low excitation energies (3.3-4.3 eV) well followed it. This result would be derived from an overpopulation among the corresponding energy levels. A probable reason for this is that excitations for the high-lying excited levels would be caused predominantly through a Penning-type collision with the metastable atom of argon or neon, followed by recombination with an electron and then stepwise de-excitations which can populate the excited energy levels just below the ionization limit of iron atom. The non-thermal excitation occurred more actively in the argon plasma rather than the neon plasma, because of a difference in the number density between the argon and the neon metastables. The Boltzmann plots yields important information on the reason why lots of Fe I lines assigned to high-lying excited levels can be emitted from glow discharge plasmas. - Highlights: Black-Right-Pointing-Pointer This paper shows the excitation mechanism of Fe I lines from a glow discharge plasma. Black-Right-Pointing-Pointer A Boltzmann distribution is studied among iron lines of various excitation levels. Black-Right-Pointing-Pointer We find an overpopulation of the high-lying energy levels from the normal distribution. Black-Right-Pointing-Pointer It is caused through Penning-type collision of iron atom with argon metastable atom.

Adsorbent synthesis of polypyrrole/TiO(2) for effective fluoride removal from aqueous solution for drinking water purification: Adsorbent characterization and adsorption mechanism.

Science.gov (United States)

Chen, Jie; Shu, Chiajung; Wang, Ning; Feng, Jiangtao; Ma, Hongyu; Yan, Wei

2017-06-01

More than 20 countries are still suffering problems of excessive fluoride containing water, and greater than 8mg/L fluoride groundwater has been reported in some villages in China. In order to meet the challenge in the drinking water defluoridation engineering, a high efficiency and affinity defluoridation adsorbent PPy/TiO 2 composite was designed and synthetized by in-situ chemical oxidative polymerization. Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction Investigator (XRD), X-ray photoelectron spectroscopy (XPS), Thermogravimetric analysis (TG), N 2 isotherm analysis, Scanning Electron Microscopy (SEM) and Zeta potential analysis were conducted to characterize surface and textural properties of the as-prepared PPy/TiO 2 , and the possibility of fluoride adsorption was carefully estimated by adsorption isotherm and kinetic studies. Characterization investigations demonstrate the uniqueness of surface and textural properties, such as suitable specific surface area and abundant positively charged nitrogen atoms (N + ), which indicate the composite is a suitable material for the fluoride adsorption. Adsorption isotherms and kinetics follow better with Langmuir and pseudo-second-order model, respectively. The maximum adsorption capacity reaches 33.178mg/g at 25°C according to Langmuir model, and particular interest was the ability to reduce the concentration of fluoride from 11.678mg/L to 1.5mg/L for drinking water at pH of 7 within 30min. Moreover, the adsorbent can be easily recycled without the loss of adsorption capacity after six cycles, greatly highlighting its outstanding affinity to fluoride, low-cost and novel to be used in the purification of fluoride containing water for drinking. Furthermore, the adsorption mechanism was extensively investigated and discussed by FTIR investigation and batch adsorption studies including effect of pH, surface potential and thermodynamics. The adsorption is confirmed to be a spontaneous and exothermic

Excitation mechanisms for Jovian seismic modes

Science.gov (United States)

Markham, Steve; Stevenson, Dave

2018-05-01

Recent (2011) results from the Nice Observatory indicate the existence of global seismic modes on Jupiter in the frequency range between 0.7 and 1.5 mHz with amplitudes of tens of cm/s. Currently, the driving force behind these modes is a mystery; the measured amplitudes are many orders of magnitude larger than anticipated based on theory analogous to helioseismology (that is, turbulent convection as a source of stochastic excitation). One of the most promising hypotheses is that these modes are driven by Jovian storms. This work constructs a framework to analytically model the expected equilibrium normal mode amplitudes arising from convective columns in storms. We also place rough constraints on Jupiter's seismic modal quality factor. Using this model, neither meteor strikes, turbulent convection, nor water storms can feasibly excite the order of magnitude of observed amplitudes. Next we speculate about the potential role of rock storms deeper in Jupiter's atmosphere, because the rock storms' expected energy scales make them promising candidates to be the chief source of excitation for Jovian seismic modes, based on simple scaling arguments. We also suggest some general trends in the expected partition of energy between different frequency modes. Finally we supply some commentary on potential applications to gravity, Juno, Cassini and Saturn, and future missions to Uranus and Neptune.

Surface-enhanced Raman Spectroscopy of Ethephone Adsorbed on Silver Surface

International Nuclear Information System (INIS)

Lee, Chul Jae; Kim, Hee Jin; Karim, Mohammad Rezaul; Lee, Mu Sang

2006-01-01

We investigated the Surface-enhanced Raman Spectroscopy (SERS) spectrum of ethephone (2- chloroethylphosphonic acid). We observed significant signals in the ordinary Raman spectrum for solid-state ethephone as well as when it was adsorbed on a colloidal silver surface, strong vibrational signals were obtained at a very low concentration. The SERS spectra were obtained by silver colloids that were prepared by the γ - irradiation method. The influence of pH and the influence of anion (Cl - , Br - , I - ) on the adsorption orientation were investigated. Two different adsorption mechanisms were deduced, depending on the experimental conditions. The chlorine atom or the chlorine and two oxygen atoms were adsorbed on the colloidal silver surface. Among halide ions, Br - and I - were more strongly adsorbed on the colloidal silver surfaces. As a result, the adsorption of ethephone was less effective due to their steric hinderance

Adsorption mechanisms of removing heavy metals and dyes from aqueous solution using date pits solid adsorbent

International Nuclear Information System (INIS)

Al-Ghouti, Mohammad A.; Li, Juiki; Salamh, Yousef; Al-Laqtah, Nasir; Walker, Gavin; Ahmad, Mohammad N.M.

2010-01-01

A potential usefulness of raw date pits as an inexpensive solid adsorbent for methylene blue (MB), copper ion (Cu 2+ ), and cadmium ion (Cd 2+ ) has been demonstrated in this work. This work was conducted to provide fundamental information from the study of equilibrium adsorption isotherms and to investigate the adsorption mechanisms in the adsorption of MB, Cu 2+ , and Cd 2+ onto raw date pits. The fit of two models, namely Langmuir and Freundlich models, to experimental data obtained from the adsorption isotherms was checked. The adsorption capacities of the raw date pits towards MB and both Cu 2+ and Cd 2+ ions obtained from Langmuir and Freundlich models were found to be 277.8, 35.9, and 39.5 mg g -1 , respectively. Surface functional groups on the raw date pits surface substantially influence the adsorption characteristics of MB, Cu 2+ , and Cd 2+ onto the raw date pits. The Fourier transform infrared spectroscopy (FTIR) studies show clear differences in both absorbances and shapes of the bands and in their locations before and after solute adsorption. Two mechanisms were observed for MB adsorption, hydrogen bonding and electrostatic attraction, while other mechanisms were observed for Cu 2+ and Cd 2+ . For Cu 2+ , binding two cellulose/lignin units together is the predominant mechanism. For Cd 2+ , the predominant mechanism is by binding itself using two hydroxyl groups in the cellulose/lignin unit.

Positronium chemistry in porous adsorbents

International Nuclear Information System (INIS)

Foti, G.; Nagy, L.G.; Moravcsik, G.; Schay, G.

1981-01-01

Kinetic studies on the annihilation of orthopositronium in porous adsorbents have been performed using lifetime spectroscopy. The positron source applied was 22 Na with 0.2 MBq activity. The adsorbents investigated were silica gels of different particle size and pore structure. The appearance of the long-lived component in the lifetime spectra can be explained by the diffusion of the orthopositronium into the pores affected by the particle size and the pore size of the adsorbent, the coverage on it and the chemical nature of the adsorbate. The long-term aim of the work is to determine and to explain these effects. (author)

Ecological applications of the irradiated adsorbents

International Nuclear Information System (INIS)

Tusseyev, T.

2004-01-01

Full text: In our previous works it was shown that after irradiation some adsorbents gain new interesting properties such as increasing (or decreasing) of their adsorption capacity, selectivity in relation to some gases, change of chemical bounds of gas molecules with adsorbent surface as well as other properties. We investigated a lot of adsorbents with semiconducting and dielectric properties. A high temperature superconductor was investigated also. Adsorbents were irradiated by ultraviolet (UV) and gamma - radiation, reactor (n.γ) - radiation, α-particles (E=40-50 MeV), protons ( E=30 MeV), and also He-3 ions (E-29-60 MeV). The following techniques were used: volumetric (manometrical), mass-spectrometer and IR spectroscopic methods, and also method of electronic - paramagnetic resonance (spin paramagnetic resonance) The obtained results allow to speak about creation of new adsorbents for gas purification (clearing) from harmful impurities, gas selection into components, an increasing of adsorbing surface. Thus one more advantage of the irradiated adsorbents is that they have 'memory effect', i.e. they can be used enough long time after irradiation. In laboratory conditions we built the small-sized adsorptive pump on the basis of the irradiated zeolites which are capable to work in autonomous conditions. It was found, that some of adsorbents after irradiation gain (or lose) selectivity in relation to definite gases. So, silica gel, which one in initial state does not adsorb hydrogen, after gamma irradiation it becomes active in relation to hydrogen. Some of rare earths oxides also show selectivity in relation to hydrogen and oxygen depending on a type of irradiation. Thus, it is possible to create different absorbents, depending on a solved problem, using a way or selection of adsorbents, either of radiation type and energy, as a result obtained adsorbents can be used for various ecological purposes

In vitro hydroxyapatite adsorbed salivary proteins

International Nuclear Information System (INIS)

Vitorino, Rui; Lobo, Maria Joao C.; Duarte, Jose; Ferrer-Correia, Antonio J.; Tomer, Kenneth B.; Dubin, Joshua R.; Domingues, Pedro M.; Amado, Francisco M.L.

2004-01-01

In spite of the present knowledge about saliva components and their respective functions, the mechanism(s) of pellicle and dental plaque formation have hitherto remained obscure. This has prompted recent efforts on in vitro studies using hydroxyapatite (HA) as an enamel model. In the present study salivary proteins adsorbed to HA were extracted with TFA and EDTA and resolved by 2D electrophoresis over a pH range between 3 and 10, digested, and then analysed by MALDI-TOF/TOF mass spectrometry and tandem mass spectrometry. Nineteen different proteins were identified using automated MS and MS/MS data acquisition. Among them, cystatins, amylase, carbonic anhydrase, and calgranulin B, were identified

Filter-adsorber aging assessment

Energy Technology Data Exchange (ETDEWEB)

Winegardner, W.K. [Pacific Northwest Laboratory, Richland, WA (United States)

1995-02-01

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.

Kosterlitz-Thouless superfluid transition for thin helium-4 films adsorbed in porous media

International Nuclear Information System (INIS)

Kotsubo, V.Y.

1985-01-01

Thin helium-4 films adsorbed in porous media with small grain sizes are studied in an attempt to understand size effects on the thin-film superfluid transition. Films were adsorbed in 500A, 3000A, and 1μ diameter packed alumina powders, and the superfluidity density was probed using third sound. The main features observed are a broadening of the transition and a reduction of third sound attenuation as the grain sizes are reduced. To explain the results, the flat-substrate Kosterlitz-Thouless theory is adapted to a finite-size system. The model, which is based on the behavior of thermally excited vortices, qualitatively agrees with the experimental results. Fits to the sound velocity data produces reasonable values for the parameters of the vortices, but quantitative agreement with the attenuation data could not be achieved. The overall results of this study suggests that the transition evolves continuously as the geometry changes form the flat substrate down to this small scale systems

Iodine removal adsorbent histories, aging and regeneration

International Nuclear Information System (INIS)

Hunt, J.R.; Rankovic, L.; Lubbers, R.; Kovach, J.L.

1976-01-01

The experience of efficiency changes with life under various test conditions is described. The adsorbents were periodically removed from both standby and continuously operating systems and tested under various test methods for residual iodine adsorption efficiency. Adsorbent from several conventional ''sampler'' cartridges versus the bulk adsorbent was also tested showing deficiency in the use of cartridge type sampling. Currently required test conditions were found inadequate to follow the aging of the adsorbent because pre-equilibration of the sample acts as a regenerant and the sample is not tested in the ''as is'' condition. The most stringent test was found to be the ambient temperature, high humidity test to follow the aging of the adsorbent. Several methods were evaluated to regenerate used adsorbents; of these high temperature steaming and partial reimpregnation were found to produce adsorbents with near identical properties of freshly prepared adsorbents

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.

New excitation and ionization mechanism of ions in dense plasmas

International Nuclear Information System (INIS)

Fujimoto, Takashi; Kato, Takako.

1981-10-01

It is shown that, in dense plasmas, dielectronic capture into doubly excited ionic states followed by the ladder-like excitation-ionization chain becomes important in the excitation-ionization process of ions. For an example of a hydrogen-like ion, its contribution to the excitation 1s → 2s, 2p and also to the ionization has been evaluated by the method of the quasi-steady-state solution to the rate equations. The increase is found to be substantial, i.e., by more than a factor of two both for the excitation and ionization rate coefficients. PACS classification: 52.25., 32.80.D sub(z), 34.80.D. (author)

Transient absorption study of two-photon excitation mechanism in the LH2 complex from purple bacterium Rhodobacter sphaeroides.

Science.gov (United States)

Stepanenko, Ilya; Kompanetz, Viktor; Makhneva, Zoya; Chekalin, Sergey; Moskalenko, Andrei; Razjivin, Andrei

2012-03-08

The mechanism of two-photon excitation of a peripheral light-harvesting complex LH2 (B800-850) from purple bacterium Rhodobacter sphaeroides was explained on the basis of femtosecond transient absorption data. Fast bleaching of the B850 absorption band was measured under two-photon excitation by 1350 nm femtosecond pulses, showing fast subpicosecond arrival of excitation energy to B850 circular aggregates. Any spectral changes connected with the B800 absorption band of B800-BChl molecules were absent. A similar picture was observed under one-photon excitation of the LH2 complex by 675 nm femtosecond pulses. We believe these effects may be attributed to direct excitation of high-energy excitonic states of a B850 circular aggregate or its vibrational manifold in accordance with the model of Abe [Chem. Phys. 2001, 264, 355-363].

Single stage batch adsorber design for efficient Eosin yellow removal by polyaniline coated ligno-cellulose.

Science.gov (United States)

Debnath, Sushanta; Ballav, Niladri; Maity, Arjun; Pillay, Kriveshini

2015-01-01

Polyaniline-coated lignin-based adsorbent (PLC) was synthesized and used for uptake of reactive dye eosin yellow (EY) from aqueous solution. The adsorption capability of the adsorbent was found to be more effective than the unmodified adsorbent (LC). In particular, the adsorption capability of the PLC was effective over a wider pH range. This could be owing to its higher point of zero charge, which is more favorable for the uptake of the anionic dye. Adsorption isotherm models suggested a monolayer adsorption was predominant. The mean free energy of adsorption (E(DR)) was found to have values between 8 and 16 kJ mol(-1) which suggests that an electrostatic mechanism of adsorption predominated over other underlying mechanisms. The adsorption process was also found to be spontaneous, with increasing negative free energy values observed at higher temperatures. Chemisorption process was supported by the changes in enthalpy above 40 kJ mol(-1) and by the results of desorption studies. This new adsorbent was also reusable and regenerable over four successive adsorption-desorption cycles. The single stage adsorber design revealed that PLC can be applicable as an effective biosorbent for the treatment of industrial effluents containing EY dye. Copyright © 2014 Elsevier B.V. All rights reserved.

Mechanisms Underlying Serotonergic Excitation of Callosal Projection Neurons in the Mouse Medial Prefrontal Cortex

Directory of Open Access Journals (Sweden)

Emily K. Stephens

2018-01-01

Full Text Available Serotonin (5-HT selectively excites subpopulations of pyramidal neurons in the neocortex via activation of 5-HT2A (2A receptors coupled to Gq subtype G-protein alpha subunits. Gq-mediated excitatory responses have been attributed primarily to suppression of potassium conductances, including those mediated by KV7 potassium channels (i.e., the M-current, or activation of non-specific cation conductances that underlie calcium-dependent afterdepolarizations (ADPs. However, 2A-dependent excitation of cortical neurons has not been extensively studied, and no consensus exists regarding the underlying ionic effector(s involved. In layer 5 of the mouse medial prefrontal cortex, we tested potential mechanisms of serotonergic excitation in commissural/callosal (COM projection neurons, a subpopulation of pyramidal neurons that exhibits 2A-dependent excitation in response to 5-HT. In baseline conditions, 5-HT enhanced the rate of action potential generation in COM neurons experiencing suprathreshold somatic current injection. This serotonergic excitation was occluded by activation of muscarinic acetylcholine (ACh receptors, confirming that 5-HT acts via the same Gq-signaling cascades engaged by ACh. Like ACh, 5-HT promoted the generation of calcium-dependent ADPs following spike trains. However, calcium was not necessary for serotonergic excitation, as responses to 5-HT were enhanced (by >100%, rather than reduced, by chelation of intracellular calcium with 10 mM BAPTA. This suggests intracellular calcium negatively regulates additional ionic conductances gated by 2A receptors. Removal of extracellular calcium had no effect when intracellular calcium signaling was intact, but suppressed 5-HT response amplitudes, by about 50%, when BAPTA was included in patch pipettes. This suggests that 2A excitation involves activation of a non-specific cation conductance that is both calcium-sensitive and calcium-permeable. M-current suppression was found to be a third

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.

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.

New type of amidoxime-group-containing adsorbent for the recovery of uranium from seawater. III. Recycle use of adsorbent

International Nuclear Information System (INIS)

Omichi, H.; Katakai, A.; Sugo, T.; Okamoto, J.

1986-01-01

An amidoxime-group adsorbent for recovering uranium from seawater was made by radiation-induced graft polymerization of acrylonitrile onto polymeric fiber, followed by amidoximation. Uranium adsorption of the adsorbent contacted with seawater in a column increased with the increase in flow rate, then leveled off. The relationship between uranium adsorption in a batch process and the ratio of the amount of seawater to that of adsorbent was found to be effective in evaluating adsorbent contacted with any amount of seawater. The conditioning of the adsorbent with an alkaline solution at higher temperature (∼80 0 C) after the acid desorption recovered the adsorption ability to the original level. This made it possible to apply the adsorbent to recycle use. On the other hand, the adsorbent conditioned at room temperature or that without conditioning lost adsorption ability during recycle use. The increase in water uptake was observed as one of the physical changes produced during recycle use of the alkaline-conditioned adsorbent, while the decrease in water uptake was observed with the unconditioned adsorbent. The IR spectra of the adsorbent showed a probability of reactions of amidoxime groups with acid and alkaline solutions, which can explain the change in uranium adsorption during the adsorption-desorption cycle

Study Under AC Stimulation on Excitement Properties of Weighted Small-World Biological Neural Networks with Side-Restrain Mechanism

International Nuclear Information System (INIS)

Yuan Wujie; Luo Xiaoshu; Jiang Pinqun

2007-01-01

In this paper, we propose a new model of weighted small-world biological neural networks based on biophysical Hodgkin-Huxley neurons with side-restrain mechanism. Then we study excitement properties of the model under alternating current (AC) stimulation. The study shows that the excitement properties in the networks are preferably consistent with the behavior properties of a brain nervous system under different AC stimuli, such as refractory period and the brain neural excitement response induced by different intensities of noise and coupling. The results of the study have reference worthiness for the brain nerve electrophysiology and epistemological science.

Cell for studying electron-adsorbed gas interactions; Cellule d'etudes des interactions electron-gaz adsorbe

Energy Technology Data Exchange (ETDEWEB)

Golowacz, H; Degras, D A [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires, Deptartement de Physique des Plasmas et de la Fusion Controlee, Service de Physique Appliquee, Service de Physique des Interractions Electroniques, Section d' Etude des Interactions Gaz-Solides

1967-07-01

The geometry and the technology of a cell used for investigations on electron-adsorbed gas interactions are described. The resonance frequencies of the surface ions which are created by the electron impact on the adsorbed gas are predicted by simplified calculations. The experimental data relative to carbon monoxide and neon are in good agreement with these predictions. (authors) [French] Les caracteristiques geometriques et technologiques generales d'une cellule d'etude des interactions entre un faisceau d'electrons et un gaz adsorbe sont donnees. Un calcul simplifie permet de prevoir les frequences de resonance des ions de surface crees par l'impact des electrons sur le gaz adsorbe. Les donnees experimentales sur l'oxyde de carbone et le neon confirment les previsions du calcul. (auteurs)

Bioavailability of Carbon Nanomaterial-Adsorbed Polycyclic Aromatic Hydrocarbons to Pimphales promelas: Influence of Adsorbate Molecular Size and Configuration.

Science.gov (United States)

Linard, Erica N; Apul, Onur G; Karanfil, Tanju; van den Hurk, Peter; Klaine, Stephen J

2017-08-15

Despite carbon nanomaterials' (CNMs) potential to alter the bioavailability of adsorbed contaminants, information characterizing the relationship between adsorption behavior and bioavailability of CNM-adsorbed contaminants is still limited. To investigate the influence of CNM morphology and organic contaminant (OC) physicochemical properties on this relationship, adsorption isotherms were generated for a suite of polycyclic aromatic hydrocarbons (PAHs) on multiwalled carbon nanotubes (MWCNTs) and exfoliated graphene (GN) in conjunction with determining the bioavailability of the adsorbed PAHs to Pimphales promelas using bile analysis via fluorescence spectroscopy. Although it appeared that GN adsorbed PAHs indiscriminately compared to MWCNTs, the subsequent bioavailability of GN-adsorbed PAHs was more sensitive to PAH morphology than MWCNTs. GN was effective at reducing bioavailability of linear PAHs by ∼70%, but had little impact on angular PAHs. MWCNTs were sensitive to molecular size, where bioavailability of two-ringed naphthalene was reduced by ∼80%, while bioavailability of the larger PAHs was reduced by less than 50%. Furthermore, the reduction in bioavailability of CNM-adsorbed PAHs was negatively correlated with the amount of CNM surface area covered by the adsorbed-PAHs. This study shows that the variability in bioavailability of CNM-adsorbed PAHs is largely driven by PAH size, configuration and surface area coverage.

Excited states configurations of the quantum Toda lattice

International Nuclear Information System (INIS)

Matsuyama, A.

2001-01-01

Excited states configurations of the quantum Toda lattice are studied by the direct diagonalization of the Hamiltonian. The most probable configurations of one-hole and one-particle excitations are shown to be similar to the profiles of classical phonon and soliton excitations, respectively. One-hole excitation states, which are always ground states of definite E m -symmetry of the dihedral group D N , change those structures abruptly with the potential range varied. One-particle excitations, which are buried in complicated excitation spectra, have well-defined configurations similar to the conoidal profile of the classical periodic Toda lattice. The relationship that the hole (particle) excitations in quantum mechanics correspond to the phonon (soliton) excitations in classical mechanics, which has been suggested based on the similarity of dispersion relations, is confirmed in a geometrically understandable way. Based on the study of one-soliton and two-soliton states, the structure of multi-soliton states in quantum mechanics can be conjectured

Elucidating the effects of adsorbent flexibility on fluid adsorption using simple models and flat-histogram sampling methods

International Nuclear Information System (INIS)

Shen, Vincent K.; Siderius, Daniel W.

2014-01-01

Using flat-histogram Monte Carlo methods, we investigate the adsorptive behavior of the square-well fluid in two simple slit-pore-like models intended to capture fundamental characteristics of flexible adsorbent materials. Both models require as input thermodynamic information about the flexible adsorbent material itself. An important component of this work involves formulating the flexible pore models in the appropriate thermodynamic (statistical mechanical) ensembles, namely, the osmotic ensemble and a variant of the grand-canonical ensemble. Two-dimensional probability distributions, which are calculated using flat-histogram methods, provide the information necessary to determine adsorption thermodynamics. For example, we are able to determine precisely adsorption isotherms, (equilibrium) phase transition conditions, limits of stability, and free energies for a number of different flexible adsorbent materials, distinguishable as different inputs into the models. While the models used in this work are relatively simple from a geometric perspective, they yield non-trivial adsorptive behavior, including adsorption-desorption hysteresis solely due to material flexibility and so-called “breathing” of the adsorbent. The observed effects can in turn be tied to the inherent properties of the bare adsorbent. Some of the effects are expected on physical grounds while others arise from a subtle balance of thermodynamic and mechanical driving forces. In addition, the computational strategy presented here can be easily applied to more complex models for flexible adsorbents

Dimensionless groups for multidimensional heat and mass transfer in adsorbed natural gas storage

Energy Technology Data Exchange (ETDEWEB)

Sphaier, L.A. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Programa de Pos-Graduacao em Engenharia Mecanica. Lab. de Mecanica Teorica e Aplicada], E-mail: lasphaier@mec.uff.br

2010-07-01

This paper provides a new methodology for analyzing heat and mass transfer in gas storage via adsorption. The foundation behind the proposed methodology comprises a set of physically meaningful dimensionless groups. A discussion regarding the development of such groups is herein presented, providing a fully normalized multidimensional formulation for describing the transport mechanisms involved in adsorbed gas storage. After such presentation, data from previous literature studies associated with the problem of adsorbed natural gas storage are employed for determining realistic values for the developed parameters. Then, a one-dimensional test-case problem is selected for illustrating the application of the dimensionless formulation for simulating the operation of adsorbed gas reservoirs. The test problem is focused on analyzing an adsorbed gas discharge operation. This problem is numerically solved, and the solution is verified against previously published literature data. The presented results demonstrate how a higher heat of sorption values lead to reduced discharge capacities. (author)

The adsorber loop concept for the contact between seawater and adsorber granulate

International Nuclear Information System (INIS)

Koske, P.H.; Ohlrogge, K.

1984-01-01

The present paper deals with the so-called ''adsorber loop concept'' in which the adsorber granulate is carried along with the seawater to be processed in a loop-like configuration and is separated again from the depleted water before this is leaving the adsorption unit. This concept enables high seawater velocities thus reducing the required bed area. Theoretical considerations are presented together with experimental results from field tests. (orig.) [de

Fruit waste adsorbent for ammonia nitrogen removal from synthetic solution: Isotherms and kinetics

Science.gov (United States)

Zahrim, AY; Lija, Y.; Ricky, L. N. S.; Azreen, I.

2016-06-01

In this study, four types of watermelon rind (WR) adsorbents; fresh WR, modified WR with sodium hydroxide (NaOH), potassium hydroxide (KOH) and sulphuric acid (H2SO4) were used as a potential low-cost adsorbent to remove NH3-N from solution. The adsorption data were fitted with the adsorption isotherm and kinetic models to predict the mechanisms and kinetic characteristics of the adsorption process. The equilibrium data agreed well with Langmuir isotherm model with highest correlation (R2=1.00). As for kinetic modelling, the adsorption process follows pseudo-second order for all four types of adsorbents which has R2 value of 1.0 and calculated adsorption capacity, Qe of 1.2148mg/g. The calculated Qe for pseudo-second order has the smallest difference with the experimental Qe and thus suggest that this adsorption process is mainly governed by chemical process involving cations sharing or exchange between WR adsorbent and NH3-N in the solution.

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

International Nuclear Information System (INIS)

Motojima, K.; Kawamura, F.

1984-01-01

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

A remarkable adsorbent for removal of contaminants of emerging concern from water: Porous carbon derived from metal azolate framework-6.

Science.gov (United States)

Bhadra, Biswa Nath; Jhung, Sung Hwa

2017-10-15

A series of metal-azolate frameworks or MAFs-MAF-4, -5, and -6-were synthesized and pyrolyzed to prepare porous carbons derived from MAFs (CDM-4, -5, -6, respectively). Not only the obtained carbons but also MAFs were characterized and applied for the adsorption of organic contaminants of emerging concern (CECs, including pharmaceuticals and personal care products) such as salicylic acid, clofibric acid, diclofenac sodium, bisphenol-A, and oxybenzone (OXB) from water. CDM-6 was found to be the most remarkable adsorbent among the tested ones (including activated carbon) for all the adsorbates. OXB was taken as a representative adsorbate for detailed adsorption studies as well as understanding the adsorption mechanism. H-bonding (H-acceptor: CDM; H-donor: CECs) was suggested as the principal mechanism for the adsorption of tested adsorbates. Finally, CDMs, especially CDM-6, were suggested as highly efficient and easily recyclable adsorbents for water purification. Copyright © 2017 Elsevier B.V. All rights reserved.

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

International Nuclear Information System (INIS)

Tsouris, Costas; Mayes, Richard T.; Janke, Christopher James; Dai, Sheng; Das, S.; Liao, W.P.; Kuo, Li-Jung; Wood, Jordana; Gill, Gary; Byers, Maggie Flicker; Schneider, Eric

2015-01-01

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

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

Excited states

CERN Document Server

Lim, Edward C

1974-01-01

Excited States, Volume I reviews radiationless transitions, phosphorescence microwave double resonance through optical spectra in molecular solids, dipole moments in excited states, luminescence of polar molecules, and the problem of interstate interaction in aromatic carbonyl compounds. The book discusses the molecular electronic radiationless transitions; the double resonance techniques and the relaxation mechanisms involving the lowest triplet state of aromatic compounds; as well as the optical spectra and relaxation in molecular solids. The text also describes dipole moments and polarizab

Volatile organic compounds adsorption using different types of adsorbent

Directory of Open Access Journals (Sweden)

Pimanmes Chanayotha

2014-09-01

Full Text Available Adsorbents were synthesized from coconut shell, coal and coke by pyrolysis followed by chemical activation process. These synthesized materials were used as adsorbents in adsorption test to determine the amount of volatile organic compounds (VOCs namely, 2-Hydroxyethyl methacrylate (HEMA, Octamethylcyclotetrasiloxane and Alkanes standard solution (C8-C20. The adsorption capacities of both synthesized adsorbents and commercial grade adsorbents (Carbotrap™ B and Carbotrap™ C were also compared. It was found that adsorbent A402, which was produced from coconut shell, activated with 40% (wt. potassium hydroxide and at activating temperature of 800°C for 1 hr, could adsorb higher amount of both HEMA and Octamethylcyclotetrasiloxane than other synthesized adsorbents. The maximum adsorption capacity of adsorbent A402 in adsorbing HEMA and Octamethylcyclotetrasiloxane were 77.87% and 50.82% respectively. These adsorption capabilities were 79.73% and 70.07% of the adsorption capacity of the commercial adsorbent Carbotrap™ B respectively. All three types of the synthesized adsorbent (A402, C302, C402 showed the capability to adsorb alkanes standard solution through the range of C8-C20 . However, their adsorption capacities were high in a specific range of C10-C11. The result from the isotherm plot was indicated that surface adsorption of synthesized adsorbent was isotherm type I while the surface adsorption of commercial adsorbent was isotherm type III.

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

KAUST Repository

Chakraborty, Anutosh; Saha, Bidyut Baran; Ng, Kim Choon; Koyama, Shigeru; Srinivasan, Kandadai

2009-01-01

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

New apparatus for measuring radon adsorption on solid adsorbents

International Nuclear Information System (INIS)

Hassan, N.M.; Hines, A.L.; Ghosh, T.K.; Loyalka, S.K.; Ketring, A.R.

1991-01-01

A new experimental system was designed to measure radon uptake by solid adsorbents from air or other carrier gases/vapors. The total amount of radon adsorbed corresponding to a specific gas-phase concentration was determined by simultaneously measuring the solid-phase and gas-phase concentrations. The system was used to measure radon adsorption isotherms on BPL activated carbon at 288, 298, and 308 K and on silica gel and molecular sieve 13X at 298 K. The isotherms were of type III according to Brunauer's classification. The heat of adsorption data indicated that the BPL activated carbon provided a heterogeneous surface for radon adsorption. The equilibrium data were correlated by the Freundlich equation. In this paper the possible adsorption mechanism and the use of the adsorption isotherms to measure indoor radon concentrations are discussed

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....

Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium.

Science.gov (United States)

Hu, Baiyang; Fugetsu, Bunshi; Yu, Hongwen; Abe, Yoshiteru

2012-05-30

We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/Prussian-blue), spongiform adsorbent with an in situ foaming procedure. Prussian blue was permanently immobilized in the cell walls of the spongiform matrix and preferentially adsorbed cesium with a theoretical capacity of 167 mg/g cesium. Cesium was absorbed primarily by an ion-exchange mechanism, and the absorption was accomplished by self-uptake of radioactive water by the quaternary spongiform adsorbent. Copyright © 2012 Elsevier B.V. All rights reserved.

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.

Method for modifying trigger level for adsorber regeneration

Science.gov (United States)

Ruth, Michael J.; Cunningham, Michael J.

2010-05-25

A method for modifying a NO.sub.x adsorber regeneration triggering variable. Engine operating conditions are monitored until the regeneration triggering variable is met. The adsorber is regenerated and the adsorbtion efficiency of the adsorber is subsequently determined. The regeneration triggering variable is modified to correspond with the decline in adsorber efficiency. The adsorber efficiency may be determined using an empirically predetermined set of values or by using a pair of oxygen sensors to determine the oxygen response delay across the sensors.

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.

Novel Fiber-Based Adsorbent Technology; FINAL

International Nuclear Information System (INIS)

Nixon, P.G.; Tsukamoto, T.; Brose, D.J.

2001-01-01

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

Application of high-resolution photoelectron spectroscopy: Vibrational resolved C 1s and O 1s spectra of CO adsorbed on Ni(100)

Energy Technology Data Exchange (ETDEWEB)

Foehlisch, A.; Nilsson, A.; Martensson, N. [Uppsala Univ. (Sweden)] [and others

1997-04-01

There are various effects which determine the line shape of a core-level electron spectrum. These are due to the finite life-time of the core hole, inelastic scattering of the outgoing photoelectron, electronic shake-up and shake-off processes and vibrational excitations. For free atoms and molecules the different contributions to the observed line shapes can often be well separated. For solids, surfaces and adsorbates the line shapes are in general much broader and it has in the past been assumed that no separation of the various contributions can be made. In the present report the authors will show that this is indeed not the case. Surprisingly, the vibrational fine structure of CO adsorbed on Ni(100) can be resolved in the C 1s and O 1s electron spectra. This was achieved by the combination of highly monochromatized soft X-rays from B18.0 with a high resolution Scienta 200 mm photoelectron spectrometer. X-ray photoelectron spectroscopy (XPS) with tunable excitation energy yields as a core level spectroscopy atomic and site-specific information. The presented measurements allow for a determination of internuclear distances and potential energy curves in corehole ionized adsorbed molecules. The authors analysis of the c(2x2) phase CO/Ni(100) on {open_quotes}top{close_quotes} yielded a vibrational splitting of 217 +/- 2 meV for C 1s ionization. For O 1s ionization a splitting of 173 +/- 8 meV was found.

Push-and-stick mechanism for charged and excited small cluster emission under ion bombardment

International Nuclear Information System (INIS)

Bitensky, I.S.; Parilis, E.S.; Wojciechowski, I.A.

1992-01-01

The mechanism for the formation, excitation and ionization of small clusters emitted under ion bombardment is discussed. It is shown that the increased degree of ionization for the transition metal dimers, trimers and tetramers can be explained by the existence of an additional effective channel for their formation, namely the associative ionization process. A simple estimate shows that the sticking together of a fast cascade atom and the pushed out surface atom is 30-40 times more effective for dimer formation, than the recombination of two fast atoms. This push-and-stick mechanism of cluster formation could also be effective for the formation of trimers and tetramers. (orig.)

Exciting Pools

Science.gov (United States)

Wright, Bradford L.

1975-01-01

Advocates the creation of swimming pool oscillations as part of a general investigation of mechanical oscillations. Presents the equations, procedure for deriving the slosh modes, and methods of period estimation for exciting swimming pool oscillations. (GS)

WGS-Adsorbent Reaction Studies at Laboratory Scale

International Nuclear Information System (INIS)

Marano, M.; Torreiro, Y.

2014-01-01

This document reports the most significant results obtained during the experimental work performed under task WGS adsorbent experimental studies within CAPHIGAS project (National Research Plan 2008-2011, ref: ENE2009-08002). The behavior of the binary adsorbent-catalyst system which will be used in the hybrid system is described in this document. Main results reported here were used during the design and development of the hybrid system adsorbent catalyst- membrane proposed in the CAPHIGAS project. The influence of main operating parameters and the optimized volume ratio adsorbent-catalyst are also presented in this report. (Author)

Acoustic and Vibration Control for an Underwater Structure under Mechanical Excitation

Directory of Open Access Journals (Sweden)

Shi-Jian Zhu

2014-01-01

Full Text Available Acoustic and vibration control for an underwater structure under mechanical excitation has been investigated by using negative feedback control algorithm. The underwater structure is modeled with cylindrical shells, conical shells, and circular bulkheads, of which the motion equations are built with the variational approach, respectively. Acoustic property is analyzed by the Helmholtz integration formulation with boundary element method. Based on negative feedback control algorithm, a control loop with a coupling use of piezoelectric sensor and actuator is built, and accordingly some numerical examples are carried out on active control of structural vibration and acoustic response. Effects of geometrical and material parameters on acoustic and vibration properties are investigated and discussed.

Physical adsorption at the nanoscale: Towards controllable scaling of the substrate-adsorbate van der Waals interaction

Science.gov (United States)

Ambrosetti, Alberto; Silvestrelli, Pier Luigi; Tkatchenko, Alexandre

2017-06-01

The Lifshitz-Zaremba-Kohn (LZK) theory is commonly considered as the correct large-distance limit for the van der Waals (vdW) interaction of adsorbates (atoms, molecules, or nanoparticles) with solid substrates. In the standard approximate form, implicitly based on local dielectric functions, the LZK approach predicts universal power laws for vdW interactions depending only on the dimensionality of the interacting objects. However, recent experimental findings are challenging the universality of this theoretical approach at finite distances of relevance for nanoscale assembly. Here, we present a combined analytical and numerical many-body study demonstrating that physical adsorption can be significantly enhanced at the nanoscale. Regardless of the band gap or the nature of the adsorbate specie, we find deviations from conventional LZK power laws that extend to separation distances of up to 10-20 nm. Comparison with recent experimental observations of ultra-long-ranged vdW interactions in the delamination of graphene from a silicon substrate reveals qualitative agreement with the present theory. The sensitivity of vdW interactions to the substrate response and to the adsorbate characteristic excitation frequency also suggests that adsorption strength can be effectively tuned in experiments, paving the way to an improved control of physical adsorption at the nanoscale.

Efficient surface enhanced Raman scattering on confeito-like gold nanoparticle-adsorbed self-assembled monolayers.

Science.gov (United States)

Chang, Chia-Chi; Imae, Toyoko; Chen, Liang-Yih; Ujihara, Masaki

2015-12-28

Confeito-like gold nanoparticles (AuNPs; average diameter = 80 nm) exhibiting a plasmon absorption band at 590 nm were adsorbed through immersion-adsorption on two self-assembled monolayers (SAMs) of 3-aminopropyltriethoxysilane (APTES-SAM) and polystyrene spheres coated with amine-terminated poly(amido amine) dendrimers (DEN/PS-SAM). The surface enhanced Raman scattering (SERS) effect on the SAM substrates was examined using the molecules of a probe dye, rhodamine 6G (R6G). The Raman scattering was strongly intensified on both substrates, but the enhancement factor (>10,000) of the AuNP/DEN/PS-SAM hierarchy substrate was 5-10 times higher than that of the AuNP/APTES-SAM substrate. This strong enhancement is attributed to the large surface area of the substrate and the presence of hot spots. Furthermore, analyzing the R6G concentration dependence of SERS suggested that the enhancement mechanism effectively excited the R6G molecules in the first layer on the hot spots and invoked the strong SERS effect. These results indicate that the SERS activity of confeito-like AuNPs on SAM substrates has high potential in molecular electronic devices and ultrasensitive analyses.

Chemical reactions of water molecules on Ru(0001) induced by selective excitation of vibrational modes

Energy Technology Data Exchange (ETDEWEB)

Mugarza, Aitor; Shimizu, Tomoko K.; Ogletree, D. Frank; Salmeron, Miquel

2009-05-07

Tunneling electrons in a scanning tunneling microscope were used to excite specific vibrational quantum states of adsorbed water and hydroxyl molecules on a Ru(0 0 0 1) surface. The excited molecules relaxed by transfer of energy to lower energy modes, resulting in diffusion, dissociation, desorption, and surface-tip transfer processes. Diffusion of H{sub 2}O molecules could be induced by excitation of the O-H stretch vibration mode at 445 meV. Isolated molecules required excitation of one single quantum while molecules bonded to a C atom required at least two quanta. Dissociation of single H{sub 2}O molecules into H and OH required electron energies of 1 eV or higher while dissociation of OH required at least 2 eV electrons. In contrast, water molecules forming part of a cluster could be dissociated with electron energies of 0.5 eV.

Thermal effects of CO2 capture by solid adsorbents: some approaches by IR image processing

International Nuclear Information System (INIS)

Benevides Ferreira, J.F.; Pradere, C.; Batsale, J.C.; Jolly, J.; Pavageau, B.; Le Bourdon, G.; Mascetti, J.; Servant, L.

2013-01-01

Thanks to infrared thermography, we have studied the mechanisms of CO 2 capture by solid adsorbents (CO 2 capture via gas adsorption on various types of porous substrates) to better understand the physico-chemical mechanisms that control CO 2 -surface interactions. In order to develop in the future an efficient process for post-combustion CO 2 capture, it is necessary to quantify the energy of adsorption of the gas on the adsorbent (exothermic process). The released heat (heat of adsorption) is a key parameter for the choice of materials and for the design of capture processes. Infrared thermography is used, at first approach, to detect the temperature fields on a thin-layer of adsorbent during CO 2 adsorption. An analytical heat transfer model was developed to evaluate the adsorption heat flux and to estimate, via an inverse technique, the heat of adsorption. The main originality of our method is to estimate heat losses directly from the heat generated during the adsorption process. Then, the estimated heat loss is taken for an a posteriori calculation of the adsorption heat flux. Finally, the heat of adsorption may be estimated. The interest in using infrared thermography is also its ability to quickly change the experimental setup, for example, to switch from the adsorbent thin-layer to the adsorbent bed configuration. We present the first results tempting to link the thin-layer data to the propagation speed of the thermal front in a milli-fluidics adsorption bed, also observed by IR thermography. (authors)

Dissolved Air Flotation of arsenic adsorbent particles

Directory of Open Access Journals (Sweden)

Mario Enrique Santander Muñoz

2015-01-01

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 poly-acrylamide (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.

Krypton retention on solid adsorbents

International Nuclear Information System (INIS)

Monson, P.R. Jr.

1982-01-01

An experimental laboratory program was conducted to develop economical solid adsorbents for the retention of krypton from a dissolver off-gas stream. The study indicates that a solid adsorbent system is feasible and competitive with other developing systems which utilize fluorocarbon absorption nd cryogenic distillation. This technology may have potential applications not only in nuclear fuel reprocessing plants, but also in nuclear reactors and in environmental monitoring. Of the 13 prospective adsorbents evaluated with respect to adsorption capacity and cost, the commercially available hydrogen mordenite was the most cost-effective material at subambient temperatures (-40 0 to -80 0 C). Silver mordenite has a higher capacity for krypton retention, but is 50 times more expensive than hydrogen mordenite

Study of radiation-induced polymerization of vinyl monomers adsorbed on inorganic substances. VIII. Polymerization of styrene and methyl methacrylate adsorbed on aerosil

International Nuclear Information System (INIS)

Fukano, K.; Kageyama, E.

1976-01-01

Aerosol is silica having a purity which is very high compared with that of silica gel and having, unlike silica gel, no micropores. To investigate the effects of impurities and micropores on the radiation-induced polymerization of styrene and methyl methacrylate adsorbed on silica gel, the radiation-induced polymerization of styrene and methyl methacrylate adsorbed on Aerosil was carried out. The results of both the styrene--Aerosil 300 system and the methyl methacrylate--Aerosil 300 system were similar to those of the styrene-silica gel and methyl methacrylate-silica gel systems, respectively. This suggests that in the radiation-induced polymerization of both styrene--silica gel and methyl methacrylate--silica gel systems the impurities and the presence of micropores have almost no effect on the reaction mechanism. The effect of aluminum as an impurity was investigated on the styrene--Aerosil MOX 170 system. It was found that aluminum accelerated the cationic polymerization

Immobilized Tannin from Sanseviera trifasciata on Carbon as Adsorbent For Iron(II in Polluted Water Source

Directory of Open Access Journals (Sweden)

Irfan Hanafi Arif

2016-03-01

Full Text Available The organic-agricultural waste resulted from local farmer or community gardening recently paid public attention. The presence and easily grown of “Lidah Mertua” or Sanseviera trifasciata being focused on potency investigation for its prospecting application. It was reported contain some phenolic and also tannin extracted from aqueous solvents. This paper revealed recent investigation applying of its isolated tannin from leave part to modifying of activated carbon. The previous report published that carbon were able to adsorb some toxic heavy metals. However, it has some limitation including lower capacity adsorption. Impregnated or immobilized the tannin-isolated from S. trifasciata leaves was able to modify the carbon functionality, physical appearance, pores size, and it adsorption capacity. Both Langmuir and Freundlich adsorption mechanism model also disclosed the developed adsorbent mechanism of iron(II adsorption on the adsorbent tannin-immobolized on carbon. The real test using community well drilling water source also gave important finding on the concentration of iron(II contained on water source.

Design, construction and test run of a solid adsorption solar refrigerator using activated carbon/methanol, as adsorbent/adsorbate pair

International Nuclear Information System (INIS)

Anyanwu, E.E.; Ezekwe, C.I.

2003-01-01

The design, construction and test run of a solid adsorption solar refrigerator are presented. It used activated carbon/methanol as the adsorbent/adsorbate pair. The refrigerator has three major components: collector/generator/adsorber, condenser and evaporator. Its flat plate type collector/generator/adsorber used clear plane glass sheet of effective exposed area of 1.2 m 2 . The steel condenser tube with a square plan view was immersed in pool of stagnant water contained in a reinforced sandcrete tank. The evaporator is a spirally coiled copper tube immersed in stagnant water. Adsorbent cooling during the adsorption process is both by natural convection of air over the collector plate and tubes and night sky radiation facilitated by removing the collector box end cover plates. Ambient temperatures during the adsorbate generation and adsorption process varied over 18.5-34 deg. C. The refrigerator yielded evaporator temperatures ranging over 1.0-8.5 deg. C from water initially in the temperature range 24-28 deg. C. Accordingly, the maximum daily useful cooling produced was 266.8 kJ/m 2 of collector area

Study on the adsorption performance of composite adsorbent of CaCl2 and expanded graphite with ammonia as adsorbate

International Nuclear Information System (INIS)

Li, S.L.; Wu, J.Y.; Xia, Z.Z.; Wang, R.Z.

2009-01-01

A novel constant volume test unit was built to study the adsorption performance of a new type composite adsorbent. This test unit can measure the adsorption isosteres of the working pairs. The adsorption isosteres are the curves of the adsorption pressure variation with the adsorption temperatures at constant adsorption quantities. Compared to the former test results of isothermals and isobars, the isosteres are better for the calculation of the adsorption heat, desorption heat and the selection the adsorption working pairs. Three experimental results were obtained: the first result was that the expanded graphite powders were superior to the expandable graphite powders to facilitate the transportation of working fluid in the composite adsorbent. The second one was that the composite adsorbent treated by solution is more homogeneous than the simple mixed composite adsorbent and the treated composite adsorbent has a better mass transfer performance. The last one was that the adsorption isosteres was the same one not only in the heating process but also in the cooling process and this performance was not relevant to the homogeneity of the composite adsorbent

Removal of lead and zinc ions from water by low cost adsorbents.

Science.gov (United States)

Mishra, P C; Patel, R K

2009-08-30

In this study, activated carbon, kaolin, bentonite, blast furnace slag and fly ash were used as adsorbent with a particle size between 100 mesh and 200 mesh to remove the lead and zinc ions from water. The concentration of the solutions prepared was in the range of 50-100 mg/L for lead and zinc for single and binary systems which are diluted as required for batch experiments. The effect of contact time, pH and adsorbent dosage on removal of lead and zinc by adsorption was investigated. The equilibrium time was found to be 30 min for activated carbon and 3h for kaolin, bentonite, blast furnace slag and fly ash. The most effective pH value for lead and zinc removal was 6 for activated carbon. pH value did not effect lead and zinc removal significantly for other adsorbents. Adsorbent doses were varied from 5 g/L to 20 g/L for both lead and zinc solutions. An increase in adsorbent doses increases the percent removal of lead and zinc. A series of isotherm studies was undertaken and the data evaluated for compliance was found to match with the Langmuir and Freundlich isotherm models. To investigate the adsorption mechanism, the kinetic models were tested, and it follows second order kinetics. Kinetic studies reveals that blast furnace slag was not effective for lead and zinc removal. The bentonite and fly ash were effective for lead and zinc removal.

Properties and behaviour of SO{sub 2} adsorbents for CFBC

Energy Technology Data Exchange (ETDEWEB)

Smith, I.M.

2007-11-15

Sulphur capture in FBC boilers usually relies on addition of limestone, which is not used efficiently. Limestones with lower sulphation capacities are undesirable because they increase the raw materials and the residues requiring management. This increases operating costs and CO{sub 2} emissions. It is preferable to use less limestone or shells instead. The performance of adsorbents varies widely and depends mainly on their morphology and microstructure rather than on their chemical properties. Adsorption mechanisms are investigated. Fragmentation and attrition are important during calcination. Sulphation is affected by boiler size, configuration, operating conditions, oxidising and reducing zones, reactions with compounds in coal ash, and attrition. Preparation and handling of limestone at the plant is examined and care has to be taken to avoid moisture in all systems. Recently designed plants achieve an SO{sub 2} capture efficiency at or over 95% with addition of adsorbent at a Ca:S molar ratio of 2-2.5 depending on the sulphur content of the fuel and the reactivity of the adsorbent. Various methods of enhancing SO{sub 2} capture are reviewed. Sorbent reactivation by pressurised steam hydration or grinding/hydration appear to be most promising but are not yet used on full-scale CFBC. Fuels and operating conditions affect emissions control and the production of residues. The adsorbent requirement may be reduced by cofiring with low sulphur high calcium fuels and by optimising the furnace temperature for different fuels. The effect of sulphur capture on other emissions ie examined. NOx and N{sub 2}O emissions may be reduced by choice of fuels and adsorbent. An increase in CO{sub 2} emissions results from minimising use of limestone or by carbonization/calcination to capture CO{sub 2} before sulphation. 110 refs., 11 figs., 10 tab.

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.

Adsorbent catalytic nanoparticles and methods of using the same

Energy Technology Data Exchange (ETDEWEB)

Slowing, Igor Ivan; Kandel, Kapil

2017-01-31

The present invention provides an adsorbent catalytic nanoparticle including a mesoporous silica nanoparticle having at least one adsorbent functional group bound thereto. The adsorbent catalytic nanoparticle also includes at least one catalytic material. In various embodiments, the present invention provides methods of using and making the adsorbent catalytic nanoparticles. In some examples, the adsorbent catalytic nanoparticles can be used to selectively remove fatty acids from feedstocks for biodiesel, and to hydrotreat the separated fatty acids.

Proposal of measuring the mechanisms of nuclear excitation leading to fission with the ADONE jet-target tagged photon beam

International Nuclear Information System (INIS)

Lucherini, V.; Bianchi, N.; De Sanctis, E.; Guaraldo, C.; Levi Sandri, P.; Muccifora, V.; Polli, E.; Reolon, A.R.; Aiello, S.; De Filippo, E.; Lanzano', G.; Lo Nigro, S.; Milone, C.; Pagano, A.; Botvina, A.S.; Iljinov, A.S.; Mebel, M.V.

1990-01-01

The mechanisms of excitation with subsequent fission of heavy nuclei can be conveniently studied by means of photons, since this probe is able to interact deeply inside the nucleus. We propose the use of the (200-1200 MeV) tagged photon beam from the ADONE Jet Target in order to study the mass-energy and total momentum distributions of fission fragments, to obtain experimental information on the configurations (excitation energy and nucleonic composition) of produced compound nuclei and on their decay channels

Non-linear excitation of gravitational radiation antennae

International Nuclear Information System (INIS)

Blair, D.G.

1982-01-01

A mechanism of non-linear excitation is proposed to explain observed excess noise in gravitational radiation antennae, driven by low frequency vibration. The mechanism is analogous to the excitation of a violin string by low frequency bowing. Numerical estimates for Weber bars suspended by cables are in good agreement with observations. (Auth.)

Excitation of giant resonances in heavy ion collisions

International Nuclear Information System (INIS)

Kuehn, W.

1991-01-01

Introduction: What are Giant Resonances? General Features of Giant Resonances, Macroscopic Description and Classification, Basic Excitation Mechanisms, Decay Modes, Giant Resonances Built on Excited States, Relativistic Coulomb Excitation of Giant Resonances, Experimental Situation. (orig.)

Prussian blue caged in spongiform adsorbents using diatomite and carbon nanotubes for elimination of cesium

Energy Technology Data Exchange (ETDEWEB)

Hu, Baiyang [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Fugetsu, Bunshi, E-mail: hu@ees.hokudai.ac.jp [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Yu, Hongwen [Graduate School of Environmental Science, Hokkaido University, Sapporo 060-0810 (Japan); Abe, Yoshiteru [Kyoei Engineering Corporation, Niigata 959-1961 (Japan)

2012-05-30

Highlights: Black-Right-Pointing-Pointer Prussian blue was sealed in cavities of diatomite using carbon nanotubes. Black-Right-Pointing-Pointer The caged Prussian blue after being permanently immobilized in polyurethane spongy showed a 167 mg/g capability for absorbing cesium. Black-Right-Pointing-Pointer Cesium elimination was accomplished by simply adding the Prussian-blue based spongiform adsorbent to radioactive water. - Abstract: We developed a spongiform adsorbent that contains Prussian blue, which showed a high capacity for eliminating cesium. An in situ synthesizing approach was used to synthesize Prussian blue inside diatomite cavities. Highly dispersed carbon nanotubes (CNTs) were used to form CNT networks that coated the diatomite to seal in the Prussian blue particles. These ternary (CNT/diatomite/Prussian-blue) composites were mixed with polyurethane (PU) prepolymers to produce a quaternary (PU/CNT/diatomite/Prussian-blue), spongiform adsorbent with an in situ foaming procedure. Prussian blue was permanently immobilized in the cell walls of the spongiform matrix and preferentially adsorbed cesium with a theoretical capacity of 167 mg/g cesium. Cesium was absorbed primarily by an ion-exchange mechanism, and the absorption was accomplished by self-uptake of radioactive water by the quaternary spongiform adsorbent.

Development of adsorbents for recovery of uranium from seawater

International Nuclear Information System (INIS)

Egawa, Hiroaki; Furusaki, Shintaro.

1987-01-01

The largest subject for putting the extraction of uranium from seawater in practical use is the development of high performance adsorbents for uranium. In this paper, the way of thinking about the development of adsorbents for extracting uranium from seawater and the recent reports on this subject are described. Next, the research on the adsorbing capacity and adsorbing rate of the adsorbents developed so far is summarized, and the way of thinking about the evaluation of adsorbent performance which is the base of the design of a system for extracting uranium from seawater is explained, taking amidoxime type adsorbent as the example. For Japan where energy resources are scant, the uranium contained in seawater, which is estimated to be about 4.2 billion t, is the most luring important element. Uranium is contained in seawater is very low concentration of 3 ppb, and exists as anion complex salt. In 1960s, the Harwell Atomic Energy Research Establishment in UK found out that titanium oxide hydrate is the most promising as the adsorbent. Also a number of organic absorbents have been developed. In order to bring adsorbents in contact with seawater, pumping, ocean current and wave force are utilized. Adsorbents are in spherical, fiber and film forms, and held as fixed beds and fluidized beds. (Kako, I.) 48 refs

Self-excitation of single nanomechanical pillars

Science.gov (United States)

Kim, Hyun S.; Qin, Hua; Blick, Robert H.

2010-03-01

Self-excitation is a mechanism that is ubiquitous for electromechanical power devices such as electrical generators. This is conventionally achieved by making use of the magnetic field component in electrical generators (Nedic and Lipo 2000 IEEE/IAS Conf. Records (Rome, Italy) vol 1 pp 51-6), a good and widely visible example of which is the wind turbine farm (Muljadi et al 2005 J. Sol. Energy Eng. 127 581-7). In other words, a static force, such as the wind acting on rotor blades, can generate a resonant excitation at a certain mechanical frequency. For nanomechanical systems (Craighead 2000 Science 290 1532-5 Roukes 2001 Phys. World 14 25-31 Cleland 2003 Foundations of Nanomechanics (Berlin: Springer); Ayari et al 2007 Nano Lett. 7 2252-7 Koenig et al 2008 Nat. Nanotechnol. 3 482-4) such a self-excitation (SE) mechanism is also highly desirable, because it can generate mechanical oscillations at radio frequencies by simply applying a dc bias voltage. This is of great importance for low-power signal communication devices and detectors, as well as for mechanical computing elements. For a particular nanomechanical system—the single electron shuttle—this effect was predicted some time ago by Gorelik et al (Phys. Rev. Lett. 80 4526-9). Here, we use a nanoelectromechanical single electron transistor (NEMSET) to demonstrate self-excitation for both the soft and hard regimes, respectively. The ability to use self-excitation in nanomechanical systems may enable the detection of quantum mechanical backaction effects (Naik et al 2006 Nature 443 193-6) in direct tunneling, macroscopic quantum tunneling (Savelev et al 2006 New J. Phys. 8 105-15) and rectification (Pistolesi and Fazio 2005 Phys. Rev. Lett. 94 036806-4). All these effects have so far been overshadowed by the large driving voltages that had to be applied.

Poorly crystalline hydroxyapatite: A novel adsorbent for enhanced fulvic acid removal from aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Wei, Wei [Department of Environmental Science and Engineering, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023 (China); Yang, Lei; Zhong, Wenhui; Cui, Jing [Department of Environmental Science and Engineering, Nanjing Normal University, Nanjing 210023 (China); Wei, Zhenggui, E-mail: weizhenggui@gmail.com [Department of Environmental Science and Engineering, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Provincial Key Laboratory of Materials Cycling and Pollution Control, Nanjing Normal University, Nanjing 210023 (China); Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing Normal University, Nanjing 210023 (China)

2015-03-30

Graphical abstract: - Highlights: • Poorly crystalline HAP was firstly used for FA removal from aqueous solution. • The maximum adsorption capacity was determined to be 90.20 mg/g at 318 K. • Adsorption kinetics, isotherms and thermodynamic have been studied in detail. • Adsorption mechanism involved surface complexation, electrostatic interaction and hydrogen bonding. - Abstract: In this study, poorly crystalline hydroxyapatite (HAP) was developed as an efficient adsorbent for the removal of fulvic acid (FA) from aqueous solution. Surface functionality, crystallinity, and morphology of the synthetic adsorbent were studied by Fourier-transformation infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of various parameters such as crystallinity of adsorbent, contact time, adsorbent dosage, pH, initial adsorbate concentration, temperature, ionic strength and the presence of alkaline earth metal ions on FA adsorption were investigated. Results indicated that the nanosized HAP calcined at lower temperature was poorly crystalline (X{sub c} = 0.23) and had better adsorption capacity for FA than those (X{sub c} = 0.52, 0.86) calcined at higher temperature. FA removal was increased with increases of adsorbent dosage, temperature, ionic strength and the presence of alkali earth metal ions, but decreased as the pH increased. Kinetic studies showed that pseudo-second-order kinetic model better described the adsorption process. Equilibrium data were best described by Sips models, and the estimated maximum adsorption capacity of poorly crystalline HAP was 90.20 mg/g at 318 K, displaying higher efficiency for FA removal than previously reported adsorbents. FT-IR results revealed that FA adsorption over the adsorbent could be attributed to the surface complexation between the oxygen atom of functional groups of FA and calcium ions of HAP. Regeneration studies indicated that HAP could be recyclable for a long

Investigation of A-3 adsorbent-ditolylmethane two-phase system

International Nuclear Information System (INIS)

Ermakov, V.A.; Benderskaya, O.S.

1988-01-01

Compatibility of A-3 adsorbent, produced on the basis of palygoskite clay, with organic coolant of nuclear reactors-ditolylmethane (DTM)- and the possibility to use the given adsorbent for DTM purification from surfactant impurities are investigated. Compatibility of the adsorbent with DTM was evaluated by the concentration of its constituents in liquid phase. Sufactant adsorption was observed by the change in acid number of coolant, optical density at λ=396 nm and adsorbate mass in the adsorbent. From spent adsorbent the coolant was washed out by n-heptane, and the adsorbate - by methylene chloride, othanol and water in succession. On the basis of the results obtained the conclusion is made that A3 possesses a high chemical stability in DTM medium, i.e. it is compatible with DTM and can be used for its purification from surfactant impurities sorbed on heat-transferring surface

Irradiation Degradation of Adsorbents for Minor Actinides Recovery

International Nuclear Information System (INIS)

Watanabe, S.; Sano, Y.; Kofuji, H.; Takeuchi, M.; Koizumi, T.

2015-01-01

Extraction chromatography is one of the promising technologies for minor actinides (MA: Am and Cm) recovery from high-level liquid waste. The degradation behaviour of the organic species in the adsorbents under radiation exposure is important to discuss the safety and durability of the adsorbent in the extraction chromatography process. In this study, gamma-ray irradiation experiments on TODGA/SiO 2 -P adsorbent were carried out to investigate the degradation products from radiolysis of the adsorbent. The degraded organic species eluted from the adsorbent and those remaining inside the adsorbent were thoroughly identified by GC/MS, FT-IR and NMR analyses. The species suspected as hydrolysis products of TODGA were mainly detected from the analyses. Since some radicals such as.H or.OH are generated by the gamma-ray irradiation on water molecules, it was discussed that the radicals products from radiolysis of HNO 3 solution are related to the degradation reaction of the extractants. (authors)

Investigations Into the Reusability of Amidoxime-Based Polymeric Uranium Adsorbents

Energy Technology Data Exchange (ETDEWEB)

Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Science Lab.; Gill, Gary A. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Science Lab.; Strivens, Jonathan E. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Science Lab.; Wood, Jordana R. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Science Lab.; Schlafer, Nicholas J. [Pacific Northwest National Lab. (PNNL), Sequim, WA (United States). Marine Science Lab.; Wai, Chien M. [Univ. of Idaho, Moscow, ID (United States); LCW Supercritical Technologies, Seattle, WA (United States); Pan, H. B. [Univ. of Idaho, Moscow, ID (United States)

2016-09-28

Significant advancements in amidoxime-based polymeric adsorbents to extract uranium from seawater are achieved in recent years. The success of uranium adsorbent development can help provide a sustainable supply of fuel for nuclear reactors. To bring down the production cost of this new technology, in addition to the development of novel adsorbents with high uranium capacity and manufacture cost, the development of adsorbent re-using technique is critical because it can further reduce the cost of the adsorbent manufacture. In our last report, the use of high concentrations of bicarbonate solution (3M KHCO3) was identified as a cost-effective, environmental friendly method to strip uranium from amidoxime-based polymeric adsorbents. This study aims to further improve the method for high recovery of uranium capacity in re-uses and to evaluate the performance of adsorbents after multiple re-use cycles. Adsorption of dissolved organic matter (DOM) on the uranium adsorbents during seawater exposure can hinder the uranium adsorption and slow down the adsorption rate. An additional NaOH rinse (0.5 M NaOH, room temperature) was applied after the 3 M KHCO3 elution to remove natural organic matter from adsorbents. The combination of 3 M KHCO3 elution and 0.5 M NaOH rinse significantly improves the recovery of uranium adsorption capacity in the re-used adsorbents. In the first re-use, most ORNL adsorbents tested achieve ~100% recovery by using 3 M KHCO3 elution + 0.5 M NaOH rinse approach, in comparison to 54% recovery when only 3 M KHCO3 elution was applied. A significant drop in capacity was observed when the adsorbents went through more than one re-use. FTIR spectra revealed that degradation of amidoxime ligands occurs during seawater exposure, and is more significant the longer the exposure time. Significantly elevated ratios of Ca/U and Mg/U in re-used adsorbents support the decrease in abundance of amidoxime ligands and increase carboxylate group from FT-IR analysis. The

Theoretical Insights Into the Excited State Double Proton Transfer Mechanism of Deep Red Pigment Alkannin.

Science.gov (United States)

Zhao, Jinfeng; Dong, Hao; Zheng, Yujun

2018-02-08

As the most important component of deep red pigments, alkannin is investigated theoretically in detail based on time-dependent density functional theory (TDDFT) method. Exploring the dual intramolecular hydrogen bonds (O1-H2···O3 and O4-H5···O6) of alkannin, we confirm the O1-H2···O3 may play a more important role in the first excited state than the O4-H5···O6 one. Infrared (IR) vibrational analyses and subsequent charge redistribution also support this viewpoint. Via constructing the S 1 -state potential energy surface (PES) and searching transition state (TS) structures, we illuminate the excited state double proton transfer (ESDPT) mechanism of alkannin is the stepwise process that can be first launched by the O1-H2···O3 hydrogen bond wire in gas state, acetonitrile (CH 3 CN) and cyclohexane (CYH) solvents. We present a novel mechanism that polar aprotic solvents can contribute to the first-step proton transfer (PT) process in the S 1 state, and nonpolar solvents play important roles in lowering the potential energy barrier of the second-step PT reaction.

Charge-transfer state excitation as the main mechanism of the photodarkening process in ytterbium-doped aluminosilicate fibres

Energy Technology Data Exchange (ETDEWEB)

Bobkov, K K; Rybaltovsky, A A; Vel' miskin, V V; Likhachev, M E; Bubnov, M M; Dianov, E M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation); Umnikov, A A; Gur' yanov, A N; Vechkanov, N N [G.G.Devyatykh Institute of Chemistry of High-Purity Substances, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation); Shestakova, I A [Open Joint-Stock Company M.F. Stel' makh Polyus Research Institute, Moscow (Russian Federation)

2014-12-31

We have studied photodarkening in ytterbium-doped fibre preforms with an aluminosilicate glass core. Analysis of their absorption and luminescence spectra indicates the formation of stable Yb{sup 2+} ions in the glass network under IR laser pumping at a wavelength λ = 915 nm and under UV irradiation with an excimer laser (λ = 193 nm). We have performed comparative studies of the luminescence spectra of the preforms and crystals under excitation at a wavelength of 193 nm. The mechanism behind the formation of Yb{sup 2+} ions and aluminium – oxygen hole centres (Al-OHCs), common to ytterbium-doped YAG crystals and aluminosilicate glass, has been identified: photoinduced Yb{sup 3+} charge-transfer state excitation. (optical fibres)

Solvent effects on the excited-state double proton transfer mechanism in the 7-azaindole dimer: a TDDFT study with the polarizable continuum model.

Science.gov (United States)

Yu, Xue-Fang; Yamazaki, Shohei; Taketsugu, Tetsuya

2017-08-30

Solvent effects on the excited-state double proton transfer (ESDPT) mechanism in the 7-azaindole (7AI) dimer were investigated using the time-dependent density functional theory (TDDFT) method. Excited-state potential energy profiles along the reaction paths in a locally excited (LE) state and a charge transfer (CT) state were calculated using the polarizable continuum model (PCM) to include the solvent effect. A series of non-polar and polar solvents with different dielectric constants were used to examine the polarity effect on the ESDPT mechanism. The present results suggest that in a non-polar solvent and a polar solvent with a small dielectric constant, ESDPT follows a concerted mechanism, similar to the case in the gas phase. In a polar solvent with a relatively large dielectric constant, however, ESDPT is likely to follow a stepwise mechanism via a stable zwitterionic intermediate in the LE state on the adiabatic potential energy surface, although inclusion of zero-point vibrational energy (ZPE) corrections again suggests the concerted mechanism. In the meantime, the stepwise reaction path involving the CT state with neutral intermediates is also examined, and is found to be less competitive than the concerted or stepwise path in the LE state in both non-polar and polar solvents. The present study provides a new insight into the experimental controversy of the ESDPT mechanism of the 7AI dimer in a solution.

Ceramics adsorbing virus and cells. Uirusu, saibo bunri ceramics

Energy Technology Data Exchange (ETDEWEB)

Hiraide, T. (Asahi Optical Co. Ltd., Tokyo (Japan))

1993-07-01

It has been reported that hydroxyapatite (HA), which is the main inorganic component of teeth and bones of homo sapiens and used for biomaterials such as artificial tooth roots, adsorbs viruses such as influenza viruses. In this article, the history of development up to now of HA and its adsorption mechanism of protein, virus, etc., are introduced. HA was applied for chromatography in 1956 becoming one of the separating and refining methods of protein and nucleic acid, then after the development of spherical porous HA, it has become applied for high speed liquid chromatography (HPLC). Also by means of a column filled with HA granules, T-cells have been able to be purified in a short time from lymphocyte which was separated from the blood of homo sapiens. Recently it has also been reported that HA granules can adsorb influenza viruses, Japanese encephalitis viruses, polio viruses and hepatitis B viruses, and a cold-preventative mask based upon this report is now on sale. 11 refs., 7 figs.

Processing method and device for iodine adsorbing material

International Nuclear Information System (INIS)

Watanabe, Shin-ichi; Shiga, Reiko.

1997-01-01

An iodine adsorbing material adsorbing silver compounds is reacted with a reducing gas, so that the silver compounds are converted to metal silver and stored. Then, the silver compounds are not melted or recrystallized even under a highly humid condition, accordingly, peeling of the adsorbed materials from a carrier can be prevented, and the iodine adsorbing material can be stored stably. Since the device is disposed in an off gas line for discharging off gases from a nuclear power facility, the iodine adsorbing material formed by depositing silver halides to the carrier is contained, and a reducing or oxidizing gas is supplied to the vessel as required, and silver halides can be converted to metal silver or the metal silver can be returned to silver halide. (T.M.)

Melatonin Nanoparticles Adsorbed to Polyethylene Glycol Microspheres as Activators of Human Colostrum Macrophages

International Nuclear Information System (INIS)

Hara, C.D.C.P.; Honorio-Frana, A.C.; Fagundes, D.L.G.; Guimares, P.C.L.; Franca, E.L.

2013-01-01

The effectiveness of hormones associated with polymeric matrices has amplified the possibility of obtaining new drugs to activate the immune system. Melatonin has been reported as an important immunomodulatory agent that can improve many cell activation processes. It is possible that the association of melatonin with polymers could influence its effects on cellular function. Thus, this study verified the adsorption of the hormone melatonin to polyethylene glycol (PEG) microspheres and analyzed its ability to modulate the functional activity of human colostrum phagocytes. Fluorescence microscopy and flow cytometry analyses revealed that melatonin was able to adsorb to the PEG microspheres. This system increased the release of superoxide and intracellular calcium. There was an increase of phagocytic and microbicidal activity by colostrum phagocytes when in the presence of melatonin adsorbed to PEG microspheres. The modified delivery of melatonin adsorbed to PEG microspheres may be an additional mechanism for its microbicidal activity and represents an important potential treatment for gastrointestinal infections of newborns.

Melatonin Nanoparticles Adsorbed to Polyethylene Glycol Microspheres as Activators of Human Colostrum Macrophages

Directory of Open Access Journals (Sweden)

Cristiane de Castro Pernet Hara

2013-01-01

Full Text Available The effectiveness of hormones associated with polymeric matrices has amplified the possibility of obtaining new drugs to activate the immune system. Melatonin has been reported as an important immunomodulatory agent that can improve many cell activation processes. It is possible that the association of melatonin with polymers could influence its effects on cellular function. Thus, this study verified the adsorption of the hormone melatonin to polyethylene glycol (PEG microspheres and analyzed its ability to modulate the functional activity of human colostrum phagocytes. Fluorescence microscopy and flow cytometry analyses revealed that melatonin was able to adsorb to the PEG microspheres. This system increased the release of superoxide and intracellular calcium. There was an increase of phagocytic and microbicidal activity by colostrum phagocytes when in the presence of melatonin adsorbed to PEG microspheres. The modified delivery of melatonin adsorbed to PEG microspheres may be an additional mechanism for its microbicidal activity and represents an important potential treatment for gastrointestinal infections of newborns.

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.

Excitation of large-amplitude parametric resonance by the mechanical stiffness modulation of a microstructure

International Nuclear Information System (INIS)

Krylov, Slava; Gerson, Yuval; Nachmias, Tali; Keren, Uri

2010-01-01

In this work we report on an approach allowing efficient parametric excitation of large-amplitude stable oscillations of a microstructure operated by a parallel-plate electrode, and present results of a theoretical and experimental investigation of the device. The frame-type structure, fabricated from a silicon on insulator (SOI) substrate using deep reactive ion etching (DRIE), consists a pair of cantilever-type suspensions connected at their ends by a link. The time-varying electrostatic force applied to the link by a parallel-plate electrode is transformed into a periodic tension of the beams, resulting in the modulation of their flexural stiffness and consequently the mechanical parametric excitation of the structure. The lateral compliance of the beams allows for large-amplitude in-plane oscillations in the direction parallel to the electrode while high axial stiffness prevents undesirable instabilities. The lumped model of the device, considered as an assembly of geometrically nonlinear massless flexures and a rigid massive link and built using the Rayleigh–Ritz method, predicted the feasibility of the excitation approach. The fabricated devices were operated in ambient air conditions by a combination of a steady (dc) and time-dependent (ac) components of voltage and the large-amplitude responses, up to 75 µm, in the vicinity of the principal parametric and primary resonances were registered by means of video acquisition and image processing. The shapes of the experimental resonant curves were consistent with those predicted by the model. The location and size of the instability regions on the frequency–voltage plane (parametric tongues) were quantitatively in good agrement with the model results. Theoretical and experimental results indicate that the suggested approach can be efficiently used for excitation of various types of microdevices where stable resonant operation combined with robustness and large vibrational amplitudes are desirable

Study of the Adsorbent-Adsorbate Interactions from Cd(II) and Pb(II) Adsorption on Activated Carbon and Activated Carbon Fiber

Energy Technology Data Exchange (ETDEWEB)

Kim, Dae Ho; Kim, Doo Won; Kim, Bohye; Yang, Kap Seung [Chonnam National Univ., Gwangju (Korea, Republic of); Lim, Yongkyun; Park, Eun Nam [Microfilter Co., Ltd, Seoul (Korea, Republic of)

2013-02-15

The adsorption characteristics of Cd(II) and Pb(II) in aqueous solution using granular activated carbon (GAC), activated carbon fiber (ACF), modified ACF (NaACF), and a mixture of GAC and NaACF (GAC/NaACF) have been studied. The surface properties, such as morphology, surface functional groups, and composition of various adsorbents were determined using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) measurements. The specific surface area, total pore volume, and pore size distribution were investigated using nitrogen adsorption, Brunauer-Emmett-Teller (BET), and Barrett-Joyner-Halenda (BJH) methods. In this study, NaACF showed a high adsorption capacity and rate for heavy metal ions due to the improvement of its ion-exchange capabilities by additional oxygen functional groups. Moreover, the GAC and NaACF mixture was used as an adsorbent to determine the adsorbent-adsorbate interaction in the presence of two competitive adsorbents.

Study of the Adsorbent-Adsorbate Interactions from Cd(II) and Pb(II) Adsorption on Activated Carbon and Activated Carbon Fiber

International Nuclear Information System (INIS)

Kim, Dae Ho; Kim, Doo Won; Kim, Bohye; Yang, Kap Seung; Lim, Yongkyun; Park, Eun Nam

2013-01-01

The adsorption characteristics of Cd(II) and Pb(II) in aqueous solution using granular activated carbon (GAC), activated carbon fiber (ACF), modified ACF (NaACF), and a mixture of GAC and NaACF (GAC/NaACF) have been studied. The surface properties, such as morphology, surface functional groups, and composition of various adsorbents were determined using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) measurements. The specific surface area, total pore volume, and pore size distribution were investigated using nitrogen adsorption, Brunauer-Emmett-Teller (BET), and Barrett-Joyner-Halenda (BJH) methods. In this study, NaACF showed a high adsorption capacity and rate for heavy metal ions due to the improvement of its ion-exchange capabilities by additional oxygen functional groups. Moreover, the GAC and NaACF mixture was used as an adsorbent to determine the adsorbent-adsorbate interaction in the presence of two competitive adsorbents

Use of Low-cost Adsorbents to Chlorophenols and Organic Matter Removal of Petrochemical Wastewater

Directory of Open Access Journals (Sweden)

Aretha Moreira de Oliveira

2013-11-01

Full Text Available The removal of 2,4 diclorophenol (2,4-DCF and 2,4,6 trichlorophenol (2,4,6 TCF present in  petrochemical wastewater was evaluated using low-cost adsorbents, such as chitin, chitosan and coconut shells. Batch studies showed that the absorption efficiency for 2,4 DCF and 2,4,6 TCF follow the order: chitosan > chitin > coconut shells. Langmuir and Freundlich models have been applied to experimental isotherms data, to better understand the adsorption mechanisms. Petrochemical wastewater treatment with fixed bed column system using chitinous adsorbents showed a removal of COD (75% , TOG (90% and turbidity (74-89%.

Optical and mechanical excitation thermography for impact response in basalt-carbon hybrid fiber-reinforced composite laminates

OpenAIRE

Zhang, Hai; Sfarra, Stefano; Sarasini, Fabrizio; Ibarra-Castanedo, Clemente; Perilli, Stefano; Fernandes, Henrique; Duan, Yuxia; Peeters, Jeroen; Avelidis, Nicholas P; Maldague, Xavier

2017-01-01

Abstract: In this paper, optical and mechanical excitation thermography were used to investigate basalt fiber reinforced polymer (BFRP), carbon fiber reinforced polymer (CFRP) and basalt-carbon fiber hybrid specimens subjected to impact loading. Interestingly, two different hybrid structures including sandwich-like and intercalated stacking sequence were used. Pulsed phase thermography (PPT), principal component thermography (PCT) and partial least squares thermography (PLST) were used to pro...

A new immobilized biomass technical adsorbent for uranium recovery from bioleach solutions in the mine

International Nuclear Information System (INIS)

Tsezos, Marios; Noh, S.H.

1988-01-01

A new type of metal adsorbent has been developed using inactive microbial biomass as the raw material. The adsorbent can be made to a desirable particle size. The particles have good mechanical strength and resistance to compression and consequently can be used in a packed bed resulting in a low pressure drop. The new biosorbents have been shown to maintain well the biosorptive properties of the immobilized biomass used for their production. We have tested successfully the new biosorbents for the recovery of uranium from actual bioleach solutions. (author)

Study on development of adsorbent of acetaldehyde; Acetaldehyde yo kyuchakuzai no kaihatsu ni kansuru kenkyu

Energy Technology Data Exchange (ETDEWEB)

Noda, T. [Nippon Steel Corp., Tokyo (Japan); Suzuki, M. [The University of Tokyo, Tokyo (Japan). Institute of Industrial Science

1997-07-10

The adsorption of acetaldehyde by porous ceramics impregnated with hydrazinium aluminum sulfate (HAS) is studied. Silicagel, activated alumina, activated clay, and activated carbon are compared, and it is found that silicagel and activated clay are suitable as a substrate for HAS impregnated adsorbent. The adsorption mechanism of acetaldehyde by the adsorbent is believed to be one in which acetaldehyde reacts with hydrazinium and yields acetaldazine. The adsorption capacity of the adsorbent at low acetaldehyde concentration of 0.1 ppm was as large as 1.36 mol/kg. This adsorption capacity at 0.1 ppm acetaldehyde concentration is remarkably larger than that of conventional activated carbon. Hydrazinium decomposes easily in the air because it is a strong reducing agent and reacts with oxygen or carbon dioxide. But hydrazinium impregnated on porous ceramics with HAS becomes more stable and maintains reactivity with acetaldehyde for longer than six months. An adsorbent made of porous ceramics impregnated with HAS is useful as a deodorant for acetaldehyde. 8 refs., 6 figs., 6 tabs.

Two-electron excitation in slow ion-atom collisions: Excitation mechanisms and interferences among autoionizing states

International Nuclear Information System (INIS)

Kimura, M.; Rice Univ., Houston, TX

1990-01-01

The two-electron capture or excitation process resulting from collisions of H + and O 6+ ions with He atoms in the energy range from 0.5 keV/amu to 5 keV/amu is studied within a molecular representation. The collision dynamics for formation of doubly excited O 4+ ions and He** atoms and their (n ell, n'ell ') populations are analyzed in conjunction with electron correlations. Autoionizing states thus formed decay through the Auger process. An experimental study of an ejected electron energy spectrum shows ample structures in addition to two characteristic peaks that are identified by atomic and molecular autoionizations. These structures are attributable to various interferences among electronic states and trajectories. We examine the dominant sources of the interferences. 12 refs., 5 figs

Participation of electronic excited states in the positronium formation mechanism in the Gd(III) pentakis (picrate) complexes with imidazolium countercations

Energy Technology Data Exchange (ETDEWEB)

Fulgêncio, F., E-mail: fefulgencio@gmail.com [Departam ento de Química – ICEx Universidade Federal de Minas Gerais – UFMG, Belo Horizonte, MG (Brazil); Borges, A.S. [Coordenadoria de Química e Biologia – Instituto Federal do Espírito Santos – IFES, Campus Vitória, ES (Brazil); Araújo, M.H. [Departam ento de Química – ICEx Universidade Federal de Minas Gerais – UFMG, Belo Horizonte, MG (Brazil); Brito, H.F. [Instituto de Química, Departamento de Química Fundamental, Universidade de São Paulo, São Paulo (Brazil); Oliveira, F.C. [Departamento de Metalurgia e Química, Centro Federal de Educação Tecnológica de Minas Gerais – CEFET-MG, Campus Timóteo, MG (Brazil); Ribeiro, T.; Windmöller, D. [Departam ento de Química – ICEx Universidade Federal de Minas Gerais – UFMG, Belo Horizonte, MG (Brazil); Magalhães, W.F., E-mail: welmag@ufmg.br [Departam ento de Química – ICEx Universidade Federal de Minas Gerais – UFMG, Belo Horizonte, MG (Brazil)

2016-02-15

In this work, positron annihilation lifetime (PALS) and optical spectroscopies measurements were performed on [Gd(pic){sub 2}(H{sub 2}O){sub 6}](pic)·6H{sub 2}O and on complexes of general formula C{sub 2}[Gd(pic){sub 5}], where pic corresponds to picrate ligands and C to the countercations butyl-methyl, hexyl-methyl, butyl-ethyl and butyl-butyl imidazoles. Since all of these complexes have high energy ligand-to-metal charge transfer states (LMCTS) but form low amounts of Positronium (Ps), the LMCTS do not act here as a mechanism that suppress luminescence nor prevents Ps formation. This result suggests that, besides LMCTS, other effects should also contribute to prevent Ps formation. The results indicate that the electron withdrawing –NO{sub 2} groups in the picrate ligand are responsible by the effect that prevents Ps formation. Also, a rough correlation between the ligands' triplet states lifetimes and Ps formation was observed. The insertion of electron donor groups (the imidazolium countercations) increased the ligands' first triplet excited states ({sup 3}π{sup ⁎}) lifetimes and Ps formation, indicating that these two spectroscopic parameters are correlated. Also, it is demonstrated that there is no clear correlation between Ps formation probability and the excitation energy of the ligands' first triplet excited states. The results were discussed in terms of the recently proposed Ps formation mechanism, named cybotactic correlated system kinetic mechanism (CCSKM), showing that the Ps formation process involves molecular excited states and is kinetically controlled. - Highlights: • PALS and optical spectroscopies measurements performed on Gd{sup 3+} complexes. • A correlation was obtained between the ligands' {sup 3}π{sup ⁎} lifetimes and Ps formation. • Electronegative groups increased the ligands' {sup 3}π{sup ⁎} lifetimes and Ps formation. • Results discussed in terms of a new Ps formation mechanism (ccskm).

Surface enhanced Raman scattering of new acridine based fluorophore adsorbed on silver electrode

Science.gov (United States)

Solovyeva, Elena V.; Myund, Liubov A.; Denisova, Anna S.

2015-10-01

4,5-Bis(N,N-di(2-hydroxyethyl)iminomethyl)acridine (BHIA) is a new acridine based fluoroionophore and a highly-selective sensor for cadmium ion. The direct interaction of the aromatic nitrogen atom with a surface is impossible since there are bulky substituents in the 4,5-positions of the acridine fragment. Nevertheless BHIA molecule shows a reliable SERS spectrum while adsorbed on a silver electrode. The analysis of SERS spectra pH dependence reveals that BHIA species adsorbed on a surface can exist in both non-protonated and protonated forms. The adsorption of BHIA from alkaline solution is accompanied by carbonaceous species formation at the surface. The intensity of such "carbon bands" turned out to be related with the supporting electrolyte (KCl) concentration. Upon lowering the electrode potential the SERS spectra of BHIA do not undergo changes but the intensity of bands decreases. This indicates that the adsorption mechanism on the silver surface is realized via aromatic system of acridine fragment. In case of such an adsorption mechanism the chelate fragment of the BHIA molecule is capable of interaction with the solution components. Addition of Cd2+ ions to a system containing BHIA adsorbed on a silver electrode in equilibrium with the solution leads to the formation of BHIA/Cd2+ complex which desorption causes the loss of SERS signal.

Excited-state molecular photoionization dynamics

International Nuclear Information System (INIS)

Pratt, S.T.

1995-01-01

This review presents a survey of work using resonance-enhanced multiphoton ionization and double-resonance techniques to study excited-state photoionization dynamics in molecules. These techniques routinely provide detail and precision that are difficult to achieve in single-photon ionization from the ground state. The review not only emphasizes new aspects of photoionization revealed in the excited-state experiments but also shows how the excited-state techniques can provide textbook illustrations of some fundamental mechanisms in molecular photoionization dynamics. Most of the examples are confined to diatomic molecules. (author)

Photodegradation mechanism of sulfonamides with excited triplet state dissolved organic matter: A case of sulfadiazine with 4-carboxybenzophenone as a proxy

International Nuclear Information System (INIS)

Li, Yingjie; Wei, Xiaoxuan; Chen, Jingwen; Xie, Hongbin; Zhang, Ya-nan

2015-01-01

Highlights: • Excited triplet state of dissolved organic matter ( 3 DOM * ) is largely responsible for the enhanced photodegradation of sulfadiazine. • Electron followed by proton transfer is a major mechanism for the reactions of sulfadiazine with 3 DOM * proxies. • Two reaction sites (amino- or sulfonyl-N) and sulfadiazine radicals were identified in the reactions of sulfadiazine with 3 DOM * proxies. - Abstract: Excited triplet states of dissolved organic matter ( 3 DOM*) are important players for photodegradation sulfonamide antibiotics (SAs) in sunlit natural waters. However, the triplet-mediated reaction mechanism was poorly understood. In this study, we investigated the reaction adopting sulfadiazine as a representative SA and 4-carboxybenzophenone (CBBP)as a proxy of DOM. Results showed that the excited triplet state of CBBP ( 3 CBBP*) is responsible for the photodegradation of sulfadiazine. The reaction of 3 CBBP* with substructure model compounds verified there are two reaction sites (amino-or sulfonyl-N atoms) of sulfadiazine. Density functional theory calculations were performed, which unveiled that electrons transfer from the N reaction sites to the carbonyl oxygen atom of 3 CBBP* moiety, followed by proton transfers, leading to the formation of sulfadiazine radicals. Laser flash photolysis experiments were performed to confirm the mechanism. Thus, this study identified that the photodegradation mechanism of SAs initiated by 3 DOM*, which is important for understanding the photochemical fate, predicting the photoproducts, and assessing the ecological risks of SAs in the aquatic environment

Regularities of radiolysis of carbon dioxide adsorbed on Zeokar-2 catalyst

International Nuclear Information System (INIS)

Rustamov, V.R.; Kurbanov, M.A.; Kerimov, V.K.; Musaeva, P.F.

1982-01-01

Kinetics of CO formation, effect of dose rate and adsorbed water on CO yield during heterogeneous gamma-radiolysis of CO 2 have been studied. Radiation-chemical yields of the products are determined. The mechanism of reactions is discussed. It is shown that the catalyst plays the role of acceptor of active intermediate particles (O - and others) and acts as a chemical reagent

The inverse problem of sensing the mass and force induced by an adsorbate on a beam nanomechanical resonator

Energy Technology Data Exchange (ETDEWEB)

Liu, Yun [Faculty of Information and Automation, Kunming University of Science and Technology, Kunming, Yunnan Province 65005 (China); Zhang, Yin [State Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100190 (China)

2016-06-08

The mass sensing superiority of a micro/nanomechanical 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 mechanical resonator sensor on two things: reducing extra experimental equipments and achieving better mass sensing by considering more factors.

Stochastic stability of mechanical systems under renewal jump process parametric excitation

DEFF Research Database (Denmark)

Iwankiewicz, R.; Nielsen, Søren R.K.; Larsen, Jesper Winther

2005-01-01

A dynamic system under parametric excitation in the form of a non-Erlang renewal jump process is considered. The excitation is a random train of nonoverlapping rectangular pulses with equal, deterministic heights. The time intervals between two consecutive jumps up (or down), are the sum of two...

Effects of real and sham whole-body mechanical vibration on spinal excitability at rest and during muscle contraction

NARCIS (Netherlands)

Hortobagyi, T.; Rider, P.; DeVita, P.

2014-01-01

We examined the effects of whole-body mechanical vibration (WBV) on indices of motoneuronal excitability at rest and during muscle contraction in healthy humans. Real and sham WBV at 30Hz had no effect on reflexes measured during muscle contraction. Real WBV at 30 and 50Hz depressed the H-reflex

Ecotoxicological Effects of Chemical Contaminants Adsorbed to Microplastics in the Clam Scrobicularia plana

Directory of Open Access Journals (Sweden)

Sarit O'Donovan

2018-04-01

Full Text Available Although microplastics (MPs are distributed globally in the marine environment, a great deal of unknowns relating to their ecotoxicological effects on the marine biota remains. Due to their lipophilic nature, microplastics have the potential to adsorb persistent organic pollutants present in contaminated regions, which may increase their detrimental impact once assimilated by organisms. This study investigates the ecotoxicological effects of exposure to low-density polyethylene (LDPE microplastics (11–13 μm, with and without adsorbed contaminants (benzo[a]pyrene—BaP and perfluorooctane sulfonic acid—PFOS, in the peppery furrow shell clam, Scrobicularia plana. Environmentally relevant concentrations of contaminants (BaP−16.87 ± 0.22 μg g−1 and PFOS−70.22 ± 12.41 μg g−1 were adsorbed to microplastics to evaluate the potential role of plastic particles as a source of chemical contamination once ingested. S. plana were exposed to microplastics, at a concentration of 1 mg L−1, in a water-sediment exposure setup for 14 days. Clams were sampled at the beginning of the experiment (day 0 and after 3, 7, and 14 days. BaP accumulation, in whole clam tissues, was analyzed. A multi-biomarker assessment was conducted in the gills, digestive gland, and haemolymph of clams to clarify the effects of exposure. This included the quantification of antioxidant (superoxide dismutase, catalase, glutathione peroxidase and biotransformation (glutathione-S-transferases enzyme activities, oxidative damage (lipid peroxidation levels, genotoxicity (single and double strand DNA breaks, and neurotoxicity (acetylcholinesterase activity. Results suggest a potential mechanical injury of gills caused by ingestion of microplastics that may also affect the analyzed biomarkers. The digestive gland seems less affected by mechanical damage caused by virgin microplastic exposure, with the MPs-adsorbed BaP and PFOS exerting a negative influence over the assessed

Nano-sized Adsorbate Structure Formation in Anisotropic Multilayer System

Science.gov (United States)

Kharchenko, Vasyl O.; Kharchenko, Dmitrii O.; Yanovsky, Vladimir V.

2017-05-01

In this article, we study dynamics of adsorbate island formation in a model plasma-condensate system numerically. We derive the generalized reaction-diffusion model for adsorptive multilayer system by taking into account anisotropy in transfer of adatoms between neighbor layers induced by electric field. It will be found that with an increase in the electric field strength, a structural transformation from nano-holes inside adsorbate matrix toward separated nano-sized adsorbate islands on a substrate is realized. Dynamics of adsorbate island sizes and corresponding distributions are analyzed in detail. This study provides an insight into details of self-organization of adatoms into nano-sized adsorbate islands in anisotropic multilayer plasma-condensate systems.

Flow boundary conditions for chain-end adsorbing polymer blends.

Science.gov (United States)

Zhou, Xin; Andrienko, Denis; Delle Site, Luigi; Kremer, Kurt

2005-09-08

Using the phenol-terminated polycarbonate blend as an example, we demonstrate that the hydrodynamic boundary conditions for a flow of an adsorbing polymer melt are extremely sensitive to the structure of the epitaxial layer. Under shear, the adsorbed parts (chain ends) of the polymer melt move along the equipotential lines of the surface potential whereas the adsorbed additives serve as the surface defects. In response to the increase of the number of the adsorbed additives the surface layer becomes thinner and solidifies. This results in a gradual transition from the slip to the no-slip boundary condition for the melt flow, with a nonmonotonic dependence of the slip length on the surface concentration of the adsorbed ends.

Membrane adsorber for endotoxin removal

Directory of Open Access Journals (Sweden)

Karina Moita de Almeida

Full Text Available ABSTRACT The surface of flat-sheet nylon membranes was modified using bisoxirane as the spacer and polyvinyl alcohol as the coating polymer. The amino acid histidine was explored as a ligand for endotoxins, aiming at its application for endotoxin removal from aqueous solutions. Characterization of the membrane adsorber, analysis of the depyrogenation procedures and the evaluation of endotoxin removal efficiency in static mode are discussed. Ligand density of the membranes was around 7 mg/g dry membrane, allowing removal of up to 65% of the endotoxins. The performance of the membrane adsorber prepared using nylon coated with polyvinyl alcohol and containing histidine as the ligand proved superior to other membrane adsorbers reported in the literature. The lack of endotoxin adsorption on nylon membranes without histidine confirmed that endotoxin removal was due to the presence of the ligand at the membrane surface. Modified membranes were highly stable, exhibiting a lifespan of approximately thirty months.

Combination of rice husk and coconut shell activated adsorbent to adsorb Pb(II) ionic metal and it’s analysis using solid-phase spectrophotometry (sps)

Science.gov (United States)

Rohmah, D. N.; Saputro, S.; Masykuri, M.; Mahardiani, L.

2018-03-01

The purpose of this research was to know the effect and determine the mass comparation which most effective combination between rice husk and coconut shell activated adsorbent to adsorb Pb (II) ion using SPS method. This research used experimental method. Technique to collecting this datas of this research is carried out by several stages, which are: (1) carbonization of rice husk and coconut shell adsorbent using muffle furnace at a temperature of 350°C for an hour; (2) activation of the rice husk and coconut shell adsorbent using NaOH 1N and ZnCl2 15% activator; (3) contacting the adsorbent of rice husk and coconut shell activated adsorbent with liquid waste simulation of Pb(II) using variation comparison of rice husk and coconut shell, 1:0; 0:1; 1:1; 2:1; 1:2; (4) analysis of Pb(II) using Solid-Phase Spectrophotometry (SPS); (5) characterization of combination rice husk and coconut shell activated adsorbent using FTIR. The result of this research show that the combined effect of combination rice husk and coconut shell activated adsorbent can increase the ability of the adsorbent to absorb Pb(II) ion then the optimum adsorbent mass ratio required for absorbing 20 mL of Pb(II) ion with a concentration of 49.99 µg/L is a ratio of 2:1 with the absorption level of 97,06%Solid-Phase Spectrophotometry (SPS) is an effective method in the level of µg/L, be marked with the Limit of Detection (LOD) of 0.03 µg/L.

Removal of adsorbent particles od copper ions by Jet flotation

International Nuclear Information System (INIS)

Santander, M.; Tapia, P.; Pavez, O.; Valderrama, L.; Guzman, D.

2009-01-01

The present study shows the results obtained on the removal of copper ions from synthetic effluents by using the adsorbent particles flotation technique (APF) in a Jet flotation cell (Jameson type). In a typical experimental run, a mineral with high quartz content was used as adsorbent particles in the adsorption and flotation experiments, to determine optimal pH conditions, adsorbent particles concentration; flotation reagents dosage and air/effluent flow ratio for applying in the Jet cell to maximize the efficiency of copper ions adsorptions and the removal of particles adsorbents containing the absorbed copper ions. The results indicate the at pH>7 and at adsorbent particles concentration of 2 kg.m - 3, 99% of copper ions is adsorbed and, when the air/effluent flow ratio applied in the Jet cell is 0,2, 98% of absorbent particles containing the adsorbed copper ions is removed. (Author) 39 refs.

Enhancement of mass transfer by ultrasound: Application to adsorbent regeneration and food drying/dehydration.

Science.gov (United States)

Yao, Ye

2016-07-01

The physical mechanisms of heat and mass transfer enhancement by ultrasound have been identified by people. Basically, the effect of 'cavitation' induced by ultrasound is the main reason for the enhancement of heat and mass transfer in a liquid environment, and the acoustic streaming and vibration are the main reasons for that in a gaseous environment. The adsorbent regeneration and food drying/dehydration are typical heat and mass transfer process, and the intensification of the two processes by ultrasound is of complete feasibility. This paper makes an overview on recent studies regarding applications of power ultrasound to adsorbent regeneration and food drying/dehydration. The concerned adsorbents include desiccant materials (typically like silica gel) for air dehumidification and other ones (typically active carbon and polymeric resin) for water treatment. The applications of ultrasound in the regeneration of these adsorbents have been proved to be energy saving. The concerned foods are mostly fruits and vegetables. Although the ultrasonic treatment may cause food degradation or nutrient loss, it can greatly reduce the food processing time and decrease drying temperature. From the literature, it can be seen that the ultrasonic conditions (i.e., acoustic frequency and power levels) are always focused on during the study of ultrasonic applications. The increasing number of relevant studies argues that ultrasound is a very promising technology applied to the adsorbent regeneration and food drying/dehydration. Copyright © 2016 Elsevier B.V. All rights reserved.

Element-specific and site-specific ion desorption from adsorbed molecules by deep core-level photoexcitation at the K-edges

CERN Document Server

Baba, Y H

2003-01-01

This article reviews our recent works on the ion desorption from adsorbed and condensed molecules at low temperature following the core-level photoexcitations using synchrotron soft x-rays. The systems investigated here are adsorbed molecules with relatively heavy molecular weight containing third-row elements such as Si, P, S, and Cl. Compared with molecules composed of second-row elements, the highly element-specific and site-specific fragment-ion desorption were observed when we tune the photon energy at the dipole-allowed 1s -> sigma sup * (3p sup *) resonance. On the basis of the resonance Auger decay spectra around the 1s ionization thresholds, the observed highly specific ion desorption is interpreted by the localization of the excited electrons (here we call as 'spectator electrons') in the antibonding sigma sup * orbital. In order to separate the direct photo-induced process from the indirect processes triggered by the secondary electrons, the photon-stimulated ion desorption was also investigated in...

The mechanism of abrupt transition between theta and hyper-excitable spiking activity in medial entorhinal cortex layer II stellate cells.

Directory of Open Access Journals (Sweden)

Tilman Kispersky

2010-11-01

Full Text Available Recent studies have shown that stellate cells (SCs of the medial entorhinal cortex become hyper-excitable in animal models of temporal lobe epilepsy. These studies have also demonstrated the existence of recurrent connections among SCs, reduced levels of recurrent inhibition in epileptic networks as compared to control ones, and comparable levels of recurrent excitation among SCs in both network types. In this work, we investigate the biophysical and dynamic mechanism of generation of the fast time scale corresponding to hyper-excitable firing and the transition between theta and fast firing frequency activity in SCs. We show that recurrently connected minimal networks of SCs exhibit abrupt, threshold-like transition between theta and hyper-excitable firing frequencies as the result of small changes in the maximal synaptic (AMPAergic conductance. The threshold required for this transition is modulated by synaptic inhibition. Similar abrupt transition between firing frequency regimes can be observed in single, self-coupled SCs, which represent a network of recurrently coupled neurons synchronized in phase, but not in synaptically isolated SCs as the result of changes in the levels of the tonic drive. Using dynamical systems tools (phase-space analysis, we explain the dynamic mechanism underlying the genesis of the fast time scale and the abrupt transition between firing frequency regimes, their dependence on the intrinsic SC's currents and synaptic excitation. This abrupt transition is mechanistically different from others observed in similar networks with different cell types. Most notably, there is no bistability involved. 'In vitro' experiments using single SCs self-coupled with dynamic clamp show the abrupt transition between firing frequency regimes, and demonstrate that our theoretical predictions are not an artifact of the model. In addition, these experiments show that high-frequency firing is burst-like with a duration modulated by an M-current.

Molecular-dynamics study of the dynamical excitations in commensurate monolayer films of nitrogen molecules on graphite: A test of the corrugation in the nitrogen-graphite potential

DEFF Research Database (Denmark)

Hansen, Flemming Yssing; Bruch, Ludwig Walter

1995-01-01

The dynamical excitations in a commensurate monolayer solid of N2 molecules adsorbed on graphite have been studied using molecular-dynamics simulations. Velocity and rotational correlation functions as well as coherent intermediate scattering functions and dynamical structure factors have been ca...

Properties and selection criteria for adsorbents

International Nuclear Information System (INIS)

Wirth, H.

1976-01-01

The paper gives a survey of the most important industrial adsorbents and of their suitability for different purposes. With special consideration of activated carbon, the properties and characteristic data are discussed which are used for assessing adsorbents. These, among other things, are as follows: specific surface area, pore size distribution, adsorption isotherms, hydrophobic properties, catalytic properties, chemical resistance, heat resistance, particle size and hardness. (orig.) [de

High energy nuclear excitations

International Nuclear Information System (INIS)

Gogny, D.; Decharge, J.

1983-09-01

The main purpose of this talk is to see whether a simple description of the nuclear excitations permits one to characterize some of the high energy structures recently observed. The discussion is based on the linear response to different external fields calculated using the Random Phase Approximation. For those structure in heavy ion collisions at excitation energies above 50 MeV which cannot be explained with such a simple approach, we discuss a possible mechanism for this heavy ion scattering

Mixed-matrix membrane adsorbers for protein separation

NARCIS (Netherlands)

Avramescu, M.E.; Borneman, Z.; Wessling, M.

2003-01-01

The separation of two similarly sized proteins, bovine serum albumin (BSA) and bovine hemoglobin (Hb) was carried out using a new type of ion-exchange mixed-matrix adsorber membranes. The adsorber membranes were prepared by incorporation of various types of Lewatit ion-exchange resins into an

Solvent cleanup using base-treated silica gel solid adsorbent

International Nuclear Information System (INIS)

Tallent, O.K.; Mailen, J.C.; Pannell, K.D.

1984-06-01

A solvent cleanup method using silica gel columns treated with either sodium hydroxide (NaOH) or lithium hydroxide (LiOH) has been investigated. Its effectiveness compares favorably with that of traditional wash methods. After treatment with NaOH solution, the gels adsorb HNO 3 , dibutyl phosphate (DBP), UO 2 2+ , Pu 4+ , various metal-ion fission products, and other species from the solvent. Adsorption mechanisms include neutralization, hydrolysis, polymerization, and precipitation, depending on the species adsorbed. Sodium dibutyl phosphate, which partially distributes to the solvent from the gels, can be stripped with water; the stripping coefficient ranges from 280 to 540. Adsorption rates are diffusion controlled such that temperature effects are relatively small. Recycle of the gels is achieved either by an aqueous elution and recycle sequence or by a thermal treatment method, which may be preferable. Potential advantages of this solvent cleanup method are that (1) some operational problems are avoided and (2) the amount of NaNO 3 waste generated per metric ton of nuclear fuel reprocessed would be reduced significantly. 19 references, 6 figures, 12 tables

Investigation of adsorption of Rhodamine B onto a natural adsorbent Argemone mexicana.

Science.gov (United States)

Khamparia, Shraddha; Jaspal, Dipika

2016-12-01

The present study aims at exploring the potential of the seeds of a tropical weed, Argemone mexicana (AM), for the removal of a toxic xanthene textile dye, Rhodamine B (RHB), from waste water. Impact of pH, adsorbent dosage, particle size, contact time and dye concentration have been assessed during adsorption. The weed has been well characterized by several latest techniques thereby providing an indepth information of the mechanism during adsorption. About 80% removal has been attained with 0.06 g of adsorbent over the studied system. Thermodynamic and kinetic studies, followed by second order kinetic model, directed towards the endothermic nature of adsorption. The results obtained from batch experiments were modelled using Langmuir and Freundlich isotherm and were analysed on the basis of R 2 and six error functions for selection of appropriate model. Langmuir isotherm was found to be best fitted to the experimental data with high values of R 2 and lower values of error functions. Adsorption study revealed the affinity of AM seeds for the dye ions present in waste water, introducing a novel adsorbent in field of waste water treatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

Efficiency of moso bamboo charcoal and activated carbon for adsorbing radioactive iodine

Energy Technology Data Exchange (ETDEWEB)

Chien, Chuan-Chi; Huang, Ying-Pin; Wang, Wie-Chieh [ITRI South, Industrial Technology Research Institute, Tainan (China); Chao, Jun-Hsing; Wei, Yuan-Yao [Nuclear Science and Technology Development Center, National Tsing Hua University, Hsinchu (China)

2011-02-15

Preventing radioactive pollution is a troublesome problem but an urgent concern worldwide because radioactive substances cause serious health-related hazards to human being. The adsorption method has been used for many years to concentrate and remove radioactive pollutants; selecting an adequate adsorbent is the key to the success of an adsorption-based pollution abatement system. In Taiwan, all nuclear power plants use activated carbon as the adsorbent to treat radiation-contaminated air emission. The activated carbon is entirely imported; its price and manufacturing technology are entirely controlled by international companies. Taiwan is rich in bamboo, which is one of the raw materials for high-quality activated carbon. Thus, a less costly activated carbon with the same or even better adsorptive capability as the imported adsorbent can be made from bamboo. The objective of this research is to confirm the adsorptive characteristics and efficiency of the activated carbon made of Taiwan native bamboo for removing {sup 131}I gas from air in the laboratory. The study was conducted using new activated carbon module assembled for treating {sup 131}I-contaminated air. The laboratory results reveal that the {sup 131}I removal efficiency for a single-pass module is as high as 70%, and the overall efficiency is 100% for four single-pass modules operated in series. The bamboo charcoal and bamboo activated carbon have suitable functional groups for adsorbing {sup 131}I and they have greater adsorption capacities than commercial activated carbons. Main mechanism is for trapping of radioiodine on impregnated charcoal, as a result of surface oxidation. When volatile radioiodine is trapped by potassium iodide-impregnated bamboo charcoal, the iodo-compound is first adsorbed on the charcoal surface, and then migrates to iodide ion sites where isotope exchange occurs. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

On the physical mechanisms governing self-excited pressure surge in Francis turbines

International Nuclear Information System (INIS)

Müller, A; Favrel, A; Landry, C; Yamamoto, K; Avellan, F

2014-01-01

The required operating range for hydraulic machines is continually extended in an effort to integrate renewable energy sources with unsteady power outputs into the existing electrical grid. The off-design operation however brings forth unfavorable flow patterns in the machine, causing dynamic problems involving cavitation, which may represent a limiting factor to the energy production. In Francis turbines it is observed that the self-excited oscillation of a vortex rope in the draft tube cone prevents the delivery of maximum power when required. This phenomenon is referred to as full load pressure surge and has been the object of extensive research during the past decades. Several contributions deepened its understanding through measurement and simulation of the local flow properties and the global stability parameters. The draft tube pressure level and the runner outlet swirl are identified as key variables in the modelling of the vortex rope dynamics. Recently, a cyclic appearance of blade cavitation has been observed at overload conditions in a multiphase numerical simulation coupling the runner and the draft tube. From the analysis of the simulation it becomes obvious that the cyclic appearance of blade cavitation has a direct effect on the runner outlet swirl, thus introducing an additional interaction mechanism that is not accounted for in formerly published models. For the presented work, the results of this numerical study are confirmed experimentally on a reduced scale model of a Francis turbine. Several wall pressure measurements in the draft tube cone are performed, together with high speed visualizations of the vortex rope and the blade cavitation. The flow swirl is calculated based on Laser Doppler Velocimetry measurements. A possible mechanism explaining the coupling between the self-excited pressure and vortex rope oscillation and the cyclic appearance of the blade cavitation is proposed. Furthermore, the streamwise propagation speed of the flow

Few Issues Related to an Electrodynamic Exciter Control

OpenAIRE

Čala, M.

2015-01-01

There are multiple problems to solve when controlling an electromagnetic exciter for vibrations generation. Main challenge is to straighten a frequency response of an exciter which is normally not uniform due to resonances resulting from the mechanical construction of an exciter, specimen to test, or mounting fixture. This paper describes number of aspects to consider, which arose during implementation of the control system for small electrodynamic exciter on the Department of Control and Ins...

Delta self-consistent field method to obtain potential energy surfaces of excited molecules on surfaces

DEFF Research Database (Denmark)

Gavnholt, Jeppe; Olsen, Thomas; Engelund, Mads

2008-01-01

is a density-functional method closely resembling standard density-functional theory (DFT), the only difference being that in Delta SCF one or more electrons are placed in higher lying Kohn-Sham orbitals instead of placing all electrons in the lowest possible orbitals as one does when calculating the ground......-state energy within standard DFT. We extend the Delta SCF method by allowing excited electrons to occupy orbitals which are linear combinations of Kohn-Sham orbitals. With this extra freedom it is possible to place charge locally on adsorbed molecules in the calculations, such that resonance energies can...... be estimated, which is not possible in traditional Delta SCF because of very delocalized Kohn-Sham orbitals. The method is applied to N2, CO, and NO adsorbed on different metallic surfaces and compared to ordinary Delta SCF without our modification, spatially constrained DFT, and inverse...

Thermodynamics of gas adsorption on solid adsorbents

International Nuclear Information System (INIS)

Budrugeac, P.

1979-01-01

Starting with several hypotheses about the adsorbtion system and the adsorption phenomenon, a thermodynamic treatment of gas adsorption on solid adsorbants is presented. The relationships for determination from isotherms and calorimetric data of thermodynamic functions are derived. The problem of the phase changes in adsorbed layer is discussed. (author)

Performance of adsorbent-embedded heat exchangers using binder-coating method

KAUST Repository

Li, Ang; Thu, Kyaw; Ismail, Azhar Bin; Shahzad, Muhammad Wakil; Ng, Kim Choon

2016-01-01

The performance of adsorption (AD) chillers or desalination cycles is dictated by the rates of heat and mass transfer of adsorbate in adsorbent-packed beds. Conventional granular-adsorbent, packed in fin-tube heat exchangers, suffered from poor heat

Direct electron-impact mechanism of excitation of mercury monobromide in a double-pulse dielectric-barrier-discharge HgBr lamp

Science.gov (United States)

Datsyuk, V. V.; Izmailov, I. A.; Naumov, V. V.; Kochelap, V. A.

2016-08-01

In a nonequlibrium plasma of a gas-discharge HgBr lamp, the terminal electronic state of the HgBr(B-X) radiative transition with a peak wavelength of 502 nm remains populated for a relatively long time and is repeatedly excited to the B state in collisions with plasma electrons. This transfer of the HgBr molecules from the ground state X to the excited state B is the main mechanism of formation of the light-emitting molecules especially when the lamp is excited by double current pulses. According to our simulations, due to the electron-induced transitions between HgBr(X) and HgBr(B), the output characteristics of the DBD lamp operating in a double-pulse regime are better than those of the lamp operating in a single-pulse regime. In the considered case, the peak power is calculated to increase by a factor of about 2 and the lamp efficiency increases by about 50%.

Selectivity of β-Sitosterol Imprinted Polymers as Adsorbent

Science.gov (United States)

Fauziah, St.; Hariani Soekamto, Nunuk; Taba, Paulina; Bachri Amran, Muh

2018-03-01

Molecularly Imprinted Polymers (MIPs) are smart materials that have been used as adsorbents in separation processes of compounds because they have a memorial effect to a certain compound. In this research, MIP synthesized was used as adsorbent for β-sitosterol. The objective of the research was to know the selectivity of MIP in adsorbing β-sitosterol. The concentrations of β-sitosterol after adsorption and desorption were analyzed by a UV-Vis spectrophotometer and the selectivity test was analyzed by HPLC. Result showed that the MIP had high adsorption ability ( qe ). The recovery of β-sitosterol from MIP for the adsorption-desorption process was 68.48%. The MIP was very selective to β-sitosterol compared to cholesterol because it can adsorb β-sitosterol as many as 100%, whereas the adsorption of cholesterol was only 30.27 %.

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

Krypton retention on solid adsorbents

International Nuclear Information System (INIS)

Monson, P.R. Jr.

1981-08-01

Over a dozen prospective adsorbents for krypton were studied and evaluated with respect to adsorption capacity and cost for dissolver off-gas streams from nuclear reprocessing plants. Results show that, at subambient temperature (-40 0 to -80 0 C), the commercially available hydrogen mordenite has sufficient adsorptive capacity to be the most cost-effective material studied. Silver mordenite has a higher capacity for krypton retention, but is 50 times more expensive than hydrogen mordenite. The results indicate that a solid adsorbent system is feasible and competitive with other developing systems whih utilize fluorocarbon absorption and cryogenic distillation

Browns Ferry charcoal adsorber incident

International Nuclear Information System (INIS)

Mays, G.T.

1979-01-01

The article reviews the temperature excursion in the charcoal adsorber beds of the Browns Ferry Unit 3 off-gas system that occurred on July 17, 1977. Significant temperature increases were experienced in the charcoal adsorber beds when charcoal fines were ignited by the ignition of a combustible mixture of hydrogen and oxygen in the off-gas system. The Browns Ferry off-gas system is described, and events leading up to and surrounding the incident are discussed. The follow-up investigation by Tennessee Valley Authority and General Electric Company personnel and their recommendations for system and operational modifications are summarized

Review of high excitation energy structures in heavy ion collisions: target excitations and three body processes

International Nuclear Information System (INIS)

Frascaria, N.

1987-09-01

A review of experimental results on high excitation energy structures in heavy ion inelastic scattering is presented. The contribution to the spectra of the pick-up break-up mechanism is discussed in the light of the data obtained with light heavy ion projectiles. Recent results obtained with 40 Ar beams at various energies will show that target excitations contribute strongly to the measured cross section

Adsorption of β-galactosidase on silica and aluminosilicate adsorbents

Science.gov (United States)

Atyaksheva, L. F.; Dobryakova, I. V.; Pilipenko, O. S.

2015-03-01

It is shown that adsorption of β-galactosidase of Aspergillus oryzae fungi on mesoporous and biporous silica and aluminosilicate adsorbents and the rate of the process grow along with the diameter of the pores of the adsorbent. It is found that the shape of the adsorption isotherms changes as well, depending on the texture of the adsorbent: the Michaelis constant rises from 0.3 mM for the enzyme in solution to 0.4-0.5 mM for the enzyme on a surface in the hydrolysis of o-nitrophenyl-β-D-galactopyranoside. It is concluded that β-galactosidase displays its maximum activity on the surface of biporous adsorbents.

Molecular Insights into the pH-Dependent Adsorption and Removal of Ionizable Antibiotic Oxytetracycline by Adsorbent Cyclodextrin Polymers

Science.gov (United States)

Zhang, Yu; Cai, Xiyun; Xiong, Weina; Jiang, Hao; Zhao, Haitong; Yang, Xianhai; Li, Chao; Fu, Zhiqiang; Chen, Jingwen

2014-01-01

Effects of pH on adsorption and removal efficiency of ionizable organic compounds (IOCs) by environmental adsorbents are an area of debate, because of its dual mediation towards adsorbents and adsorbate. Here, we probe the pH-dependent adsorption of ionizable antibiotic oxytetracycline (comprising OTCH2 +, OTCH±, OTC−, and OTC2−) onto cyclodextrin polymers (CDPs) with the nature of molecular recognition and pH inertness. OTCH± commonly has high adsorption affinity, OTC− exhibits moderate affinity, and the other two species have negligible affinity. These species are evidenced to selectively interact with structural units (e.g., CD cavity, pore channel, and network) of the polymers and thus immobilized onto the adsorbents to different extents. The differences in adsorption affinity and mechanisms of the species account for the pH-dependent adsorption of OTC. The mathematical equations are derived from the multiple linear regression (MLR) analysis of quantitatively relating adsorption affinity of OTC at varying pH to adsorbent properties. A combination of the MLR analysis for OTC and molecular recognition of adsorption of the species illustrates the nature of the pH-dependent adsorption of OTC. Based on this finding, γ-HP-CDP is chosen to adsorb and remove OTC at pH 5.0 and 7.0, showing high removal efficiency and strong resistance to the interference of coexisting components. PMID:24465975

Contribution of Adsorbed Protein Films to Nanoscopic Vibrations Exhibited by Bacteria Adhering through Ligand-Receptor Bonds.

Science.gov (United States)

Song, Lei; Sjollema, Jelmer; Norde, Willem; Busscher, Henk J; van der Mei, Henny C

2015-09-29

Bacteria adhering to surfaces exhibit nanoscopic vibrations that depend on the viscoelasticity of the bond. The quantification of the nanoscopic vibrations of bacteria adhering to surfaces provides new opportunities to better understand the properties of the bond through which bacteria adhere and the mechanisms by which they resist detachment. Often, however, bacteria do not adhere to bare surfaces but to adsorbed protein films, on which adhesion involves highly specific ligand-receptor binding next to nonspecific DLVO interaction forces. Here we determine the contribution of adsorbed salivary protein and fibronectin films to vibrations exhibited by adhering streptococci and staphylococci, respectively. The streptococcal strain used has the ability to adhere to adsorbed salivary proteins films through antigen I/II ligand-receptor binding, while the staphylococcal strain used adheres to adsorbed fibronectin films through a proteinaceous ligand-receptor bond. In the absence of ligand-receptor binding, electrostatic interactions had a large impact on vibration amplitudes of adhering bacteria on glass. On an adsorbed salivary protein film, vibration amplitudes of adhering streptococci depended on the film softness as determined by QCM-D and were reduced after film fixation using glutaraldehyde. On a relatively stiff fibronectin film, cross-linking the film in glutaraldehyde hardly reduced its softness, and accordingly fibronectin film softness did not contribute to vibration amplitudes of adhering staphylococci. However, fixation of the staphylococcus-fibronectin bond further decreased vibration amplitudes, while fixation of the streptococcus bond hardly impacted vibration amplitudes. Summarizing, this study shows that both the softness of adsorbed protein films and the properties of the bond between an adhering bacterium and an adsorbed protein film play an important role in bacterial vibration amplitudes. These nanoscopic vibrations reflect the viscoelasticity of the

Probability of collective excited state decay

International Nuclear Information System (INIS)

Manykin, Eh.A.; Ozhovan, M.I.; Poluehktov, P.P.

1987-01-01

Decay mechanisms of condensed excited state formed of highly excited (Rydberg) atoms are considered, i.e. stability of so-called Rydberg substance is analyzed. It is shown that Auger recombination and radiation transitions are the basic processes. The corresponding probabilities are calculated and compared. It is ascertained that the ''Rydberg substance'' possesses macroscopic lifetime (several seconds) and in a sense it is metastable

Production of Flocculants, Adsorbents, and Dispersants from Lignin.

Science.gov (United States)

Chen, Jiachuan; Eraghi Kazzaz, Armin; AlipoorMazandarani, Niloofar; Hosseinpour Feizi, Zahra; Fatehi, Pedram

2018-04-10

Currently, lignin is mainly produced in pulping processes, but it is considered as an under-utilized chemical since it is being mainly used as a fuel source. Lignin contains many hydroxyl groups that can participate in chemical reactions to produce value-added products. Flocculants, adsorbents, and dispersants have a wide range of applications in industry, but they are mainly oil-based chemicals and expensive. This paper reviews the pathways to produce water soluble lignin-based flocculants, adsorbents, and dispersants. It provides information on the recent progress in the possible use of these lignin-based flocculants, adsorbents, and dispersants. It also critically discusses the advantages and disadvantages of various approaches to produce such products. The challenges present in the production of lignin-based flocculants, adsorbents, and dispersants and possible scenarios to overcome these challenges for commercial use of these products in industry are discussed.

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...... separations are fast, gentle, scaleable, easily automated, can achieve separations that would be impossible or impractical to achieve by other techniques, and have demonstrated credibility in a wide range of disciplines, including minerals processing, wastewater treatment, molecular biology, cell sorting...

Hexadimethrine-montmorillonite nanocomposite: Characterization and application as a pesticide adsorbent

International Nuclear Information System (INIS)

Gámiz, B.; Hermosín, M.C.; Cornejo, J.; Celis, R.

2015-01-01

Graphical abstract: - Highlights: • Characterization of hexadimethrine-montmorillonite nanocomposite was appraised. • Comparative studies with traditional HDTMA-montmorillonite were performed. • We investigated the pesticide adsorption mechanisms displayed by the nanocomposites. • Hexadimethrine-nanocomposite showed selective affinity for anionic pesticides. - Abstract: The goal of this work was to prepare and characterize a novel functional material by the modification of SAz-1 montmorillonite with the cationic polymer hexadimethrine (SA-HEXAD), and to explore the potential use of this nanocomposite as a pesticide adsorbent. Comparative preparation and characterization with the well-known hexadecyltrimethylammonium-modified SAz-1 montmorillonite (SA-HDTMA) was also assessed. The characterization was performed by elemental analysis, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), physisorption of N 2 , scanning electron microscopy (SEM) and Z potential measurements. The characterization and adsorption experiments showed that the extent of pesticide adsorption was markedly subjected to the structure and features of the surface of each organo-clay and also to the nature of the considered pesticide. SA-HEXAD displayed a high affinity for anionic pesticides which, presumably, were adsorbed by electrostatic attraction on positively-charged ammonium groups of the polymer not directly interacting with the clay. In contrast, SA-HDTMA displayed great adsorption of both uncharged and anionic pesticides with predominance of hydrophobic interactions. This work provided information about the surface properties of a new organic–inorganic nanohybrid material, SA-HEXAD, and its potential as an adsorbent for the removal of anionic organic pollutants from aqueous solutions

Stochastic stability of mechanical systems under renewal jump process parametric excitation

DEFF Research Database (Denmark)

Iwankiewicz, R.; Nielsen, Søren R.K.; Larsen, Jesper Winther

2005-01-01

independent, negative exponential distributed variables; hence, the arrival process may be termed as a generalized Erlang renewal process. The excitation process is governed by the stochastic equation driven by two independent Poisson processes, with different parameters. If the response in a single mode...... is investigated, the problem is governed in the state space by two stochastic equations, because the stochastic equation for the excitation process is autonomic. However due to the parametric nature of the excitation, the nonlinear term appears at the right-hand sides of the equations. The equations become linear...... of the stochastic equation governing the natural logarithm of the hyperspherical amplitude process and using the modification of the method wherein the time averaging of the pertinent expressions is replaced by ensemble averaging. It is found that the direct simulation is more suitable and that the asymptotic mean...

A nuclear standard high-efficiency adsorber for iodine

International Nuclear Information System (INIS)

Wang Jianmin; Qian Yinge

1988-08-01

The structure of a nuclear standard high-efficiency adsorber, adsorbent and its performance are introduced. The performance and structure were compared with the same kind product of other firms. The results show that the leakage rate is less than 0.005%

Controllable Catalysis with Nanoparticles: Bimetallic Alloy Systems and Surface Adsorbates

KAUST Repository

Chen, Tianyou

2016-05-16

Transition metal nanoparticles are privileged materials in catalysis due to their high specific surface areas and abundance of active catalytic sites. While many of these catalysts are quite useful, we are only beginning to understand the underlying catalytic mechanisms. Opening the “black box” of nanoparticle catalysis is essential to achieve the ultimate goal of catalysis by design. In this Perspective we highlight recent work addressing the topic of controlled catalysis with bimetallic alloy and “designer” adsorbate-stabilized metal nanoparticles.

Controllable Catalysis with Nanoparticles: Bimetallic Alloy Systems and Surface Adsorbates

KAUST Repository

Chen, Tianyou; Rodionov, Valentin

2016-01-01

Transition metal nanoparticles are privileged materials in catalysis due to their high specific surface areas and abundance of active catalytic sites. While many of these catalysts are quite useful, we are only beginning to understand the underlying catalytic mechanisms. Opening the “black box” of nanoparticle catalysis is essential to achieve the ultimate goal of catalysis by design. In this Perspective we highlight recent work addressing the topic of controlled catalysis with bimetallic alloy and “designer” adsorbate-stabilized metal nanoparticles.

Noble gas separation with the use of inorganic adsorbents

International Nuclear Information System (INIS)

Pence, D.T.; Chou, C.C.; Christian, J.D.; Paplawsky, W.J.

1979-01-01

A noble gas separation process is proposed for application to airborne nuclear fuel reprocessing plant effluents. The process involves the use of inorganic adsorbents for the removal of contaminant gases and noble gas separation through selective adsorption. Water and carbon dioxide are removed with selected zeolites that do not appreciably adsorb the noble gases. Xenon is essentially quantitatively removed with a specially developed adsorbent using conventional adsorption-desorption techniques. Oxygen is removed to low ppM levels by the use of a rapid cycle adsorption technique on a special adsorbent leaving a krypton-nitrogen mixture. Krypton is separated from nitrogen with a special adsorbent operated at about -80 0 C. Because the separation process does not require high pressures and oxygen is readily removed to sufficiently limit ozone formation to insignificant levels, appreciable capital and operating cost savings with this process are possible compared with other proposed processes. In addition, the proposed process is safer to operate

Nuclear spin and isospin excitations

International Nuclear Information System (INIS)

Osterfeld, F.

1992-01-01

A review is given of our present knowledge of collective spin-isospin excitations in nuclei. Most of this knowledge comes from intermediate-energy charge-exchange reactions and from inelastic electron- and proton-scattering experiments. The nuclear-spin dynamics is governed by the spin-isospin-dependent two-nucleon interaction in the medium. This interaction gives rise to collective spin modes such as the giant Gamow-Teller resonances. An interesting phenomenon is that the measured total Gamow-Teller transition strength in the resonance region is much less than a model-independent sum rule predicts. Two physically different mechanisms have been discussed to explain this so-called quenching of the total Gamow-Teller strength: coupling to subnuclear degrees of freedom in the form of Δ-isobar excitation and ordinary nuclear configuration mixing. Both detailed nuclear structure calculations and extensive analyses of the scattering data suggest that the nuclear configuration mixing effect is the more important quenching mechanism, although subnuclear degrees of freedom cannot be ruled out. The quenching phenomenon occurs for nuclear-spin excitations at low excitation energies (ω∼10--20 MeV) and small-momentum transfers (q≤0.5 fm -1 ). A completely opposite effect is anticipated in the high (ω,q)-transfer region (0≤ω≤500 MeV, 0.5≤q≤3 fm -1 ). The nuclear spin-isospin response might be enhanced due to the attractive pion field inside the nucleus. Charge-exchange reactions at GeV incident energies have been used to study the quasifree peak region and the Δ-resonance region. An interesting result of these experiments is that the Δ excitation in the nucleus is shifted downwards in energy relative to the Δ excitation of the free proton

Resonance energy transfer from solid to adsorbed molecules under radiolysis of the N2O-MgO system

International Nuclear Information System (INIS)

Volkov, A.I.

1986-01-01

The radiolysis mechanism of nitrous oxide adsorbed on magnesia has been studied at 77 K using e.s.r. spectroscopy and chromatography. The radiative decomposition of nitrous oxide is shown to take place not only during the dissociative capture of electrons, but also during the interaction of its molecules with magnesia exitons. At a monolayer coverage theta 2 O molecules and exitons to a molecular one as a result of raising the irradiation temperature of nitrous oxide adsorbed on magnesia (theta=0.5) has been revealed. (author)

Neutralization of Rubidium Adsorbate Electric Fields by Electron Attachment

Energy Technology Data Exchange (ETDEWEB)

Sedlacek, J. A. [Univ. of Oklahoma, Norman, OK (United States); Kim, E. [Univ. of Nevada, Las Vegas, NV (United States); Rittenhouse, S. T. [Western Washington Univ., Bellingham, WA (United States); US Naval Academy, Annapolis, MD (United States); Weck, Philippe F [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Sadeghpour, H. R. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Shaffer, J. P. [Univ. of Oklahoma, Norman, OK (United States)

2015-10-01

We investigate the (0001) surface of single crystal quartz with a submonolayer of Rb adsorbates. Using Rydberg atom electromagnetically induced transparency, we investigate the electric elds resulting from Rb adsorbed on the quartz surface, and measure the activation energy of the Rb adsorbates. We show that the Rb induces a negative electron affnity (NEA) on the quartz surface. The NEA surface allows for low energy electrons to bind to the surface and cancel the electric eld from the Rb adsorbates. Our results have implications for integrating Rydberg atoms into hybrid quantum systems and the fundamental study of atom-surface interactions, as well as applications for electrons bound to a 2D surface.

Characterization of novel adsorbents for radiostrontium reduction in foods

International Nuclear Information System (INIS)

Puziy, A.M.; Bengtsson, G.B.; Hansen, H.S.

1999-01-01

Distribution coefficients, pH dependence, isotherms, kinetics and breakthrough curves of Sr binding have been measured on several types of adsorbents (carbons modified with titanium silicate, crystalline titanium silicate, mixed titanium-manganese oxide, and synthetic zeolites A4 and P) from different water solutions. It is concluded that acid-base properties of the adsorbent is very important for Sr binding. Titanium silicate based adsorbents had reduced chemical stability in an artificial food fluid below pH 2, the mixed titanium manganese oxide below pH 6, zeolite A4 below pH 5 and zeolite P below pH 7. Consideration is given to the feasibility of the adsorbents for food decontamination. (author)

Methyl iodide tests on used adsorbents

International Nuclear Information System (INIS)

Kovach, J.L.

1993-01-01

This paper discusses the history of events leading to the current problems in radioiodine test conditions. These radioiodine tests are performed in the adsorbent media from both safety and non-safety related Nuclear Air Treatment Systems (NATS). The main problem addressed is that currently there are still numerous plant technical specifications for NATS which reference outdated test protocols for the surveillance testing of the radioactive methyl iodide performance of the adsorbents. Recommendations for correcting the test condition problems are presented. 7 refs

Adsorption characteristics of benzene on biosolid adsorbent and commercial activated carbons.

Science.gov (United States)

Chiang, Hung-Lung; Lin, Kuo-Hsiung; Chen, Chih-Yu; Choa, Ching-Guan; Hwu, Ching-Shyung; Lai, Nina

2006-05-01

This study selected biosolids from a petrochemical waste-water treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl2) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl2-immersed biosolids pyrolyzed at 500 degrees C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high.

Production of Flocculants, Adsorbents, and Dispersants from Lignin

Directory of Open Access Journals (Sweden)

Jiachuan Chen

2018-04-01

Full Text Available Currently, lignin is mainly produced in pulping processes, but it is considered as an under-utilized chemical since it is being mainly used as a fuel source. Lignin contains many hydroxyl groups that can participate in chemical reactions to produce value-added products. Flocculants, adsorbents, and dispersants have a wide range of applications in industry, but they are mainly oil-based chemicals and expensive. This paper reviews the pathways to produce water soluble lignin-based flocculants, adsorbents, and dispersants. It provides information on the recent progress in the possible use of these lignin-based flocculants, adsorbents, and dispersants. It also critically discusses the advantages and disadvantages of various approaches to produce such products. The challenges present in the production of lignin-based flocculants, adsorbents, and dispersants and possible scenarios to overcome these challenges for commercial use of these products in industry are discussed.

QM/MM studies on the excited-state relaxation mechanism of a semisynthetic dTPT3 base.

Science.gov (United States)

Guo, Wei-Wei; Zhang, Teng-Shuo; Fang, Wei-Hai; Cui, Ganglong

2018-02-14

Semisynthetic alphabets can potentially increase the genetic information stored in DNA through the formation of unusual base pairs. Recent experiments have shown that near-visible-light irradiation of the dTPT3 chromophore could lead to the formation of a reactive triplet state and of singlet oxygen in high quantum yields. However, the detailed excited-state relaxation paths that populate the lowest triplet state are unclear. Herein, we have for the first time employed the QM(MS-CASPT2//CASSCF)/MM method to explore the spectroscopic properties and excited-state relaxation mechanism of the aqueous dTPT3 chromophore. On the basis of the results, we have found that (1) the S 2 ( 1 ππ*) state of dTPT3 is the initially populated excited singlet state upon near-visible light irradiation; and (2) there are two efficient relaxation pathways to populate the lowest triplet state, i.e. T 1 ( 3 ππ*). In the first one, the S 2 ( 1 ππ*) system first decays to the S 1 ( 1 nπ*) state near the S 2 /S 1 conical intersection, which is followed by an efficient S 1 → T 1 intersystem crossing process at the S 1 /T 1 crossing point; in the second one, an efficient S 2 → T 2 intersystem crossing takes place first, and then, the T 2 ( 3 nπ*) system hops to the T 1 ( 3 ππ*) state through an internal conversion process at the T 2 /T 1 conical intersection. Moreover, an S 2 /S 1 /T 2 intersection region is found to play a vital role in the excited-state relaxation. These new mechanistic insights help in understanding the photophysics and photochemistry of unusual base pairs.

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.

Black molecular adsorber coatings for spaceflight applications

Science.gov (United States)

Abraham, Nithin S.; Hasegawa, Mark M.; Straka, Sharon A.

2014-09-01

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.

Friction and diffusion dynamics of adsorbates at surfaces

NARCIS (Netherlands)

Fusco, C.

2005-01-01

A theoretical study of the motion of adsorbates (e. g. atoms, molecules or clusters) on solid surfaces is presented, with a focus on surface diffusion and atomic-scale friction. These two phenomena are inextricably linked, because when an atomic or molecular adsorbate diffuses, or is pulled, it

Synthesis and properties of porous zeolite aluminosilicate adsorbents

International Nuclear Information System (INIS)

Shilina, A.S.; Milinchuk, V.K.; Burukhin, S.B.; Gordienko, A.B.

2015-01-01

Environmentally safe non-energy-intensive methods of the synthesis have been developed and the properties of solid inorganic nanostructured zeolite-like adsorbents of a broad spectrum have been studied. The sorption capacities of the adsorbents with respect to various components of water pollution have been determined [ru

The development of an adsorbent for corrosion products in high-temperature water

International Nuclear Information System (INIS)

Kim, Yong Ik; Sung, Ki Woung; Kim, Kwang Rag; Kim, Yu Hwan; Koo, Jae Hyoo

1996-08-01

In order to use as adsorbent for removal of the soluble corrosion products, mainly Co 60 under PWR reactor coolant conditions (300 deg C, 160 kg/cm 2 ), stable ZrO 2 adsorbent was prepared using sol-gel process from zirconyl nitrate, AlO adsorbent was prepared by hydrolysis of aluminum isopropoxide, and titanium tetraisopropoxide, respectively. The prepared adsorbents were calcined at various temperature and analyzed by physical properties and the Co 2+ adsorption capacity. And it was shown that the Co 2+ adsorption capacity of the TiO 2 -Al 2 O 3 adsorbents were found to have larger than that of ZrO 2 and Al 2 O 3 adsorbents in high-temperature water. ZrO 2 , Al 2 O 3 and TiO 2 -Al 2 O 3 adsorbents were found to be suitable high-temperature adsorbents for the removal of dissolved corrosion products, mainly Co in PWR reactor coolant conditions. 15 tabs., 51 figs., 55 refs. (Author)

Creation of the technical adsorbent from local raw materials

International Nuclear Information System (INIS)

Isobaev, M.D.; Davlatnazarova, M.D.; Abdullaev, T.H.

2016-01-01

The results showed the possibility of obtaining effective adsorbents of walnut shell and the sunflower for environmental purposes, in particular for the purification of polluted waters from heavy metals. It has been shown, that 1 g of walnut shell adsorbent can adsorb on its surface ions of lead in amount of 47% by weight. The dependence of the adsorption activity of the semi-coke received from walnut shell from particle size and concentration of the solution. (author)

Eliminating Heavy Metals from Water with NanoSheet Minerals as Adsorbents

Directory of Open Access Journals (Sweden)

Shaoxian Song

2017-12-01

Full Text Available Heavy metals usually referred to those with atomic weights ranging from 63.5 to 200.6. Because of natural-mineral dissolution and human activities such as mining, pesticides, fertilizer, metal planting and batteries manufacture, etc., these heavy metals, including zinc, copper, mercury, lead, cadmium and chromium have been excessively released into water courses, like underground water, lake and river, etc. The ingestion of the heavy metals-contaminated water would raise serious health problems to human beings even at a low concentration. For instance, lead can bring human beings about barrier to the normal function of kidney, liver and reproductive system, while zinc can cause stomach cramps, skin irritations, vomiting and anemia. Mercury is a horrible neurotoxin that may result in damages to the central nervous system, dysfunction of pulmonary and kidney, chest and dyspnea. Chromium (VI has been proved can cause many diseases ranging from general skin irritation to severe lung carcinoma. Accordingly, the World Health Organization announced the maximum contaminant levels (MCL for the heavy metals in drinking water. There are numerous processes for eliminating heavy metals from water in order to provide citizens safe drinking water, including precipitation, adsorption, ion exchange, membrane separation and biological treatment, etc. Adsorption is considered as a potential process for deeply removing heavy metals, in which the selection of adsorbents plays a predominant role. Nano-sheet minerals as the adsorbents are currently the hottest researches in the field. They are obtained from layered minerals, such as montmorillonite, graphite and molybdenite, through the processing of intercalation, electrochemical and mechanical exfoliation, etc. Nano-sheet minerals are featured by their large specific surface area, relatively low costs and active adsorbing sites, leading to be effective and potential adsorbents for heavy metals removal from water

Low concentration CO2 capture using physical adsorbents: Are Metal-Organic Frameworks becoming the new benchmark materials?

KAUST Repository

Belmabkhout, Youssef; Guillerm, Vincent; Eddaoudi, Mohamed

2016-01-01

The capture and separation of traces and concentrated CO2 from important commodities such as CH4, H2, O2 and N2, is becoming important in many areas related to energy security and environmental sustainability. While trace CO2 concentration removal applications have been modestly studied for decades, the spike in interest in the capture of concentrated CO2 was motivated by the need for new energy vectors to replace highly concentrated carbon fuels and the necessity to reduce emissions from fossil fuel-fired power plants. CO2 capture from various gas streams, at different concentrations, using physical adsorbents, such as activated carbon, zeolites, and metal-organic frameworks (MOFs), is attractive. However, the adsorbents must be designed with consideration of many parameters including CO2 affinity, kinetics, energetics, stability, capture mechanism, in addition to cost. Here, we perform a systematic analysis regarding the key technical parameters that are required for the best CO2 capture performance using physical adsorbents. We also experimentally demonstrate a suitable material model of Metal Organic Framework as advanced adsorbents with unprecedented properties for CO2 capture in a wide range of CO2 concentration. These recently developed class of MOF adsorbents represent a breakthrough finding in the removal of traces CO2 using physical adsorption. This platform shows colossal tuning potential for more efficient separation agents.

Low concentration CO2 capture using physical adsorbents: Are Metal-Organic Frameworks becoming the new benchmark materials?

KAUST Repository

Belmabkhout, Youssef

2016-03-30

The capture and separation of traces and concentrated CO2 from important commodities such as CH4, H2, O2 and N2, is becoming important in many areas related to energy security and environmental sustainability. While trace CO2 concentration removal applications have been modestly studied for decades, the spike in interest in the capture of concentrated CO2 was motivated by the need for new energy vectors to replace highly concentrated carbon fuels and the necessity to reduce emissions from fossil fuel-fired power plants. CO2 capture from various gas streams, at different concentrations, using physical adsorbents, such as activated carbon, zeolites, and metal-organic frameworks (MOFs), is attractive. However, the adsorbents must be designed with consideration of many parameters including CO2 affinity, kinetics, energetics, stability, capture mechanism, in addition to cost. Here, we perform a systematic analysis regarding the key technical parameters that are required for the best CO2 capture performance using physical adsorbents. We also experimentally demonstrate a suitable material model of Metal Organic Framework as advanced adsorbents with unprecedented properties for CO2 capture in a wide range of CO2 concentration. These recently developed class of MOF adsorbents represent a breakthrough finding in the removal of traces CO2 using physical adsorption. This platform shows colossal tuning potential for more efficient separation agents.

Prediction of mechanical fatigue caused by multiple random excitations

NARCIS (Netherlands)

Bonte, M.H.A.; de Boer, Andries; Liebregts, R.

2004-01-01

A simulation method is presented for the fatigue analysis of automotive and other products that are subjected to multiple random excitations. The method is denoted as frequency domain stress-life fatigue analysis and was implemented in the automotive industry at DAF Trucks N.V. in Eindhoven, The

Removal of VOCs from air stream with corrugated sheet as adsorbent

Directory of Open Access Journals (Sweden)

Rabia Arshad

2016-10-01

Full Text Available A large proportional of volatile organic compounds (VOCs are released into the environment from various industrial processes. The current study elucidates an application of a simple adsorption phenomenon for removal of three main types of VOCs, i.e., benzene, xylene and toluene, from an air stream. Two kinds of adsorbents namely acid digested adsorbent and activated carbon are prepared to assess the removal efficiency of each adsorbent in the indoor workplace environment. The results illustrate that the adsorbents prepared from corrugated sheets were remarkably effective for the removal of each pollutant type. Nevertheless, activated carbon showed high potential of adsorbing the targeted VOC compared to the acid digested adsorbent. The uptake by the adsorbents was in the following order: benzene > xylene > toluene. Moreover, maximum adsorption of benzene, toluene and xylene occurred at 20 °C and 1.5 cm/s for both adsorbents whereas minimum success was attained at 30 °C and 1.0 cm/s. However, adsorption pattern are found to be similar for each of the the three aromatic hydrocarbons. It is concluded that the corrugated sheets waste can be a considered as a successful and cost-effective solution towards effective removal of targeted pollutants in the air stream.

Mechanism of Selenite Removal by a Mixed Adsorbent Based on Fe–Mn Hydrous Oxides Studied Using X-ray Absorption Spectroscopy

KAUST Repository

Chubar, Natalia

2014-11-18

© 2014 American Chemical Society. Selenium cycling in the environment is greatly controlled by various minerals, including Mn and Fe hydrous oxides. At the same time, such hydrous oxides are the main inorganic ion exchangers suitable (on the basis of their chemical nature) to sorb (toxic) anions, separating them from water solutions. The mechanism of selenite adsorption by the new mixed adsorbent composed of a few (amorphous and crystalline) phases [maghemite, MnCO3, and X-ray amorphous Fe(III) and Mn(III) hydrous oxides] was studied by extended X-ray absorption fine structure (EXAFS) spectroscopy [supported by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) data]. The complexity of the porous adsorbent, especially the presence of the amorphous phases of Fe(III) and Mn(III) hydrous oxides, is the main reason for its high selenite removal performance demonstrated by batch and column adsorption studies shown in the previous work. Selenite was bound to the material via inner-sphere complexation (via oxygen) to the adsorption sites of the amorphous Fe(III) and Mn(III) oxides. This anion was attracted via bidentate binuclear corner-sharing coordination between SeO3 2- trigonal pyramids and both FeO6 and MnO6 octahedra; however, the adsorption sites of Fe(III) hydrous oxides played a leading role in selenite removal. The contribution of the adsorption sites of Mn(III) oxide increased as the pH decreased from 8 to 6. Because most minerals have a complex structure (they are seldom based on individual substances) of various crystallinity, this work is equally relevant to environmental science and environmental technology because it shows how various solid phases control cycling of chemical elements in the environment.

Mechanism of Selenite Removal by a Mixed Adsorbent Based on Fe–Mn Hydrous Oxides Studied Using X-ray Absorption Spectroscopy

KAUST Repository

Chubar, Natalia; Gerda, Vasyl; Szlachta, Małgorzata

2014-01-01

© 2014 American Chemical Society. Selenium cycling in the environment is greatly controlled by various minerals, including Mn and Fe hydrous oxides. At the same time, such hydrous oxides are the main inorganic ion exchangers suitable (on the basis of their chemical nature) to sorb (toxic) anions, separating them from water solutions. The mechanism of selenite adsorption by the new mixed adsorbent composed of a few (amorphous and crystalline) phases [maghemite, MnCO3, and X-ray amorphous Fe(III) and Mn(III) hydrous oxides] was studied by extended X-ray absorption fine structure (EXAFS) spectroscopy [supported by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) data]. The complexity of the porous adsorbent, especially the presence of the amorphous phases of Fe(III) and Mn(III) hydrous oxides, is the main reason for its high selenite removal performance demonstrated by batch and column adsorption studies shown in the previous work. Selenite was bound to the material via inner-sphere complexation (via oxygen) to the adsorption sites of the amorphous Fe(III) and Mn(III) oxides. This anion was attracted via bidentate binuclear corner-sharing coordination between SeO3 2- trigonal pyramids and both FeO6 and MnO6 octahedra; however, the adsorption sites of Fe(III) hydrous oxides played a leading role in selenite removal. The contribution of the adsorption sites of Mn(III) oxide increased as the pH decreased from 8 to 6. Because most minerals have a complex structure (they are seldom based on individual substances) of various crystallinity, this work is equally relevant to environmental science and environmental technology because it shows how various solid phases control cycling of chemical elements in the environment.

Adsorption characteristics of benzene on biosolid adsorbent and commercial activated carbons

Energy Technology Data Exchange (ETDEWEB)

Hung-Lung Chiang; Kuo-Hsiung Lin; Chih-Yu Chen; Ching-Guan Choa; Ching-Shyung Hwu; Nina Lai [China Medical University, Taichung (Taiwan). Department of Risk Management

2006-05-15

This study selected biosolids from a petrochemical wastewater treatment plant as the raw material. The sludge was immersed in 0.5-5 M of zinc chloride (ZnCl{sub 2}) solutions and pyrolyzed at different temperatures and times. Results indicated that the 1-M ZnCl{sub 2}-immersed biosolids pyrolyzed at 500{sup o}C for 30 min could be reused and were optimal biosolid adsorbents for benzene adsorption. Pore volume distribution analysis indicated that the mesopore contributed more than the macropore and micropore in the biosolid adsorbent. The benzene adsorption capacity of the biosolid adsorbent was 65 and 55% of the G206 (granular-activated carbon) and BPL (coal-based activated carbon; Calgon, Carbon Corp.) activated carbons, respectively. Data from the adsorption and desorption cycles indicated that the benzene adsorption capacity of the biosolid adsorbent was insignificantly reduced compared with the first-run capacity of the adsorbent; therefore, the biosolid adsorbent could be reused as a commercial adsorbent, although its production cost is high. 18 refs., 9 figs., 3 tabs.

Resonant and nonresonant transfer and excitation in Si11+ + He collisions

International Nuclear Information System (INIS)

Clark, M.W.

1988-01-01

For many years now, dielectronic recombination (DR) has been discussed as a possible energy loss mechanism in high temperature plasmas (e.g. stars). The process is basically the inverse Auger process and involves the capture of a free electron by an ion and the simultaneous excitation of an inner shell electron of the ion producing a doubly excited state. The DR process also includes the radiative deexcitation of the ion and hence represents an energy loss from the plasma since the plasma is essentially transparent to the photons. If, instead of a free electron, an electron that is weakly bound to an atom is captured and an inner shell electron of the ion is excited, the same excited states are produced as in DR. Because the bound electrons have a momentum distribution (Compton profile), individual doubly excited states cannot, in general, be observed in this case. This new process has been called Resonant Transfer and Excitation (RTE). There is also a competing mechanism for RTE in which excitation occurs via the interaction between a projectile ion electron and a target nucleus and the capture occurs because of the interaction of the projectile nucleus and a target electron. This competing mechanism has been termed Nonresonant Transfer and Excitation (NTE) Measurements have been performed to measure RTE and NTE cross sections. A discussion of the theory, methods, and results is included

The Role of Electronic Excitations on Chemical Reaction Dynamics at Metal, Semiconductor and Nanoparticle Surfaces

Energy Technology Data Exchange (ETDEWEB)

Tully, John C. [Yale Univ., New Haven, CT (United States)

2017-06-10

Chemical reactions are often facilitated and steered when carried out on solid surfaces, essential for applications such as heterogeneous catalysis, solar energy conversion, corrosion, materials processing, and many others. A critical factor that can determine the rates and pathways of chemical reactions at surfaces is the efficiency and specificity of energy transfer; how fast does energy move around and where does it go? For reactions on insulator surfaces energy transfer generally moves in and out of vibrations of the adsorbed molecule and the underlying substrate. By contrast, on metal surfaces, metallic nanoparticles and semiconductors, another pathway for energy flow opens up, excitation and de-excitation of electrons. This so-called “nonadiabatic” mechanism often dominates the transfer of energy and can directly impact the course of a chemical reaction. Conventional computational methods such as molecular dynamics simulation do not account for this nonadiabatic behavior. The current DOE-BES funded project has focused on developing the underlying theoretical foundation and the computational methodology for the prediction of nonadiabatic chemical reaction dynamics at surfaces. The research has successfully opened up new methodology and new applications for molecular simulation. In particular, over the last three years, the “Electronic Friction” theory, pioneered by the PI, has now been developed into a stable and accurate computational method that is sufficiently practical to allow first principles “on-the-fly” simulation of chemical reaction dynamics at metal surfaces.

Search for Excited Leptons at LEP

CERN Document Server

Achard, P.; Aguilar-Benitez, M.; Alcaraz, J.; Alemanni, G.; Allaby, J.; Aloisio, A.; Alviggi, M.G.; Anderhub, H.; Andreev, Valery P.; Anselmo, F.; Arefev, A.; Azemoon, T.; Aziz, T.; Bagnaia, P.; Bajo, A.; Baksay, G.; Baksay, L.; Baldew, S.V.; Banerjee, S.; Banerjee, Sw.; Barczyk, A.; Barillere, R.; Bartalini, P.; Basile, M.; Batalova, N.; Battiston, R.; Bay, A.; Becattini, F.; Becker, U.; Behner, F.; Bellucci, L.; Berbeco, R.; Berdugo, J.; Berges, P.; Bertucci, B.; Betev, B.L.; Biasini, M.; Biglietti, M.; Biland, A.; Blaising, J.J.; Blyth, S.C.; Bobbink, G.J.; Bohm, A.; Boldizsar, L.; Borgia, B.; Bottai, S.; Bourilkov, D.; Bourquin, M.; Braccini, S.; Branson, J.G.; Brochu, F.; Burger, J.D.; Burger, W.J.; Cai, X.D.; Capell, M.; Cara Romeo, G.; Carlino, G.; Cartacci, A.; Casaus, J.; Cavallari, F.; Cavallo, N.; Cecchi, C.; Cerrada, M.; Chamizo, M.; Chang, Y.H.; Chemarin, M.; Chen, A.; Chen, G.; Chen, G.M.; Chen, H.F.; Chen, H.S.; Chiefari, G.; Cifarelli, L.; Cindolo, F.; Clare, I.; Clare, R.; Coignet, G.; Colino, N.; Costantini, S.; de la Cruz, B.; Cucciarelli, S.; van Dalen, J.A.; de Asmundis, R.; Deglon, P.; Debreczeni, J.; Degre, A.; Dehmelt, K.; Deiters, K.; della Volpe, D.; Delmeire, E.; Denes, P.; DeNotaristefani, F.; De Salvo, A.; Diemoz, M.; Dierckxsens, M.; Dionisi, C.; Dittmar, M.; Doria, A.; Dova, M.T.; Duchesneau, D.; Duda, M.; Echenard, B.; Eline, A.; El Hage, A.; El Mamouni, H.; Engler, A.; Eppling, F.J.; Extermann, P.; Falagan, M.A.; Falciano, S.; Favara, A.; Fay, J.; Fedin, O.; Felcini, M.; Ferguson, T.; Fesefeldt, H.; Fiandrini, E.; Field, J.H.; Filthaut, F.; Fisher, P.H.; Fisher, W.; Fisk, I.; Forconi, G.; Freudenreich, K.; Furetta, C.; Galaktionov, Iouri; Ganguli, S.N.; Garcia-Abia, Pablo; Gataullin, M.; Gentile, S.; Giagu, S.; Gong, Z.F.; Grenier, Gerald Jean; Grimm, O.; Gruenewald, M.W.; Guida, M.; van Gulik, R.; Gupta, V.K.; Gurtu, A.; Gutay, L.J.; Haas, D.; Hakobyan, R.S.; Hansen, J.M.; Hatzifotiadou, D.; Hebbeker, T.; Herve, Alain; Hirschfelder, J.; Hofer, H.; Hohlmann, M.; Holzner, G.; Hou, S.R.; Hu, Y.; Jin, B.N.; Jones, Lawrence W.; de Jong, P.; Josa-Mutuberria, I.; Kafer, D.; Kaur, M.; Kienzle-Focacci, M.N.; Kim, J.K.; Kirkby, Jasper; Kittel, W.; Klimentov, A.; Konig, A.C.; Kopal, M.; Koutsenko, V.; Kraber, M.; Kraemer, R.W.; Kruger, A.; Kunin, A.; Ladron de Guevara, P.; Laktineh, I.; Landi, G.; Lebeau, M.; Lebedev, A.; Lebrun, P.; Lecomte, P.; Lecoq, P.; Le Coultre, P.; Le Goff, J.M.; Leiste, R.; Levtchenko, M.; Levtchenko, P.; Li, C.; Likhoded, S.; Lin, C.H.; Lin, W.T.; Linde, F.L.; Lista, L.; Liu, Z.A.; Lohmann, W.; Longo, E.; Lu, Y.S.; Luci, C.; Luminari, L.; Lustermann, W.; Ma, W.G.; Malgeri, L.; Malinin, A.; Mana, C.; Mans, J.; Martin, J.P.; Marzano, F.; Mazumdar, K.; McNeil, R.R.; Mele, S.; Merola, L.; Meschini, M.; Metzger, W.J.; Mihul, A.; Milcent, H.; Mirabelli, G.; Mnich, J.; Mohanty, G.B.; Muanza, G.S.; Muijs, A.J.M.; Musicar, B.; Musy, M.; Nagy, S.; Natale, S.; Napolitano, M.; Nessi-Tedaldi, F.; Newman, H.; Nisati, A.; Kluge, Hannelies; Ofierzynski, R.; Organtini, G.; Pal, I.; Palomares, C.; Paolucci, P.; Paramatti, R.; Passaleva, G.; Patricelli, S.; Paul, Thomas Cantzon; Pauluzzi, M.; Paus, C.; Pauss, F.; Pedace, M.; Pensotti, S.; Perret-Gallix, D.; Petersen, B.; Piccolo, D.; Pierella, F.; Pioppi, M.; Piroue, P.A.; Pistolesi, E.; Plyaskin, V.; Pohl, M.; Pojidaev, V.; Pothier, J.; Prokofev, D.; Quartieri, J.; Rahal-Callot, G.; Rahaman, Mohammad Azizur; Raics, P.; Raja, N.; Ramelli, R.; Rancoita, P.G.; Ranieri, R.; Raspereza, A.; Razis, P.; Ren, D.; Rescigno, M.; Reucroft, S.; Riemann, S.; Riles, Keith; Roe, B.P.; Romero, L.; Rosca, A.; Rosier-Lees, S.; Roth, Stefan; Rosenbleck, C.; Rubio, J.A.; Ruggiero, G.; Rykaczewski, H.; Sakharov, A.; Saremi, S.; Sarkar, S.; Salicio, J.; Sanchez, E.; Schafer, C.; Schegelsky, V.; Schopper, H.; Schotanus, D.J.; Sciacca, C.; Servoli, L.; Shevchenko, S.; Shivarov, N.; Shoutko, V.; Shumilov, E.; Shvorob, A.; Son, D.; Souga, C.; Spillantini, P.; Steuer, M.; Stickland, D.P.; Stoyanov, B.; Straessner, A.; Sudhakar, K.; Sultanov, G.; Sun, L.Z.; Sushkov, S.; Suter, H.; Swain, J.D.; Szillasi, Z.; Tang, X.W.; Tarjan, P.; Tauscher, L.; Taylor, L.; Tellili, B.; Teyssier, D.; Timmermans, Charles; Ting, Samuel C.C.; Ting, S.M.; Tonwar, S.C.; Toth, J.; Tully, C.; Tung, K.L.; Ulbricht, J.; Valente, E.; Van de Walle, R.T.; Vasquez, R.; Veszpremi, V.; Vesztergombi, G.; Vetlitsky, I.; Vicinanza, D.; Viertel, G.; Villa, S.; Vivargent, M.; Vlachos, S.; Vodopianov, I.; Vogel, H.; Vogt, H.; Vorobev, I.; Vorobyov, A.A.; Wadhwa, M.; Wang, Q.; Wang, X.L.; Wang, Z.M.; Weber, M.; Wienemann, P.; Wilkens, H.; Wynhoff, S.; Xia, L.; Xu, Z.Z.; Yamamoto, J.; Yang, B.Z.; Yang, C.G.; Yang, H.J.; Yang, M.; Yeh, S.C.; Zalite, A.; Zalite, Yu.; Zhang, Z.P.; Zhao, J.; Zhu, G.Y.; Zhu, R.Y.; Zhuang, H.L.; Zichichi, A.; Zimmermann, B.; Zoller, M.

2003-01-01

A search for charged and neutral excited leptons is performed in 217 pb-1 of data collected with the L3 detector at LEP at centre-of-mass energies up to 209 GeV. The pair- and single-production mechanisms are investigated and no signals are detected. Combining with L3 results from searches at lower centre-of-mass energies, gives improved limits on the masses and couplings of excited leptons.

Competitive Adsorption of a Two-Component Gas on a Deformable Adsorbent

OpenAIRE

Usenko, A. S.

2013-01-01

We investigate the competitive adsorption of a two-component gas on the surface of an adsorbent whose adsorption properties vary in adsorption due to the adsorbent deformation. The essential difference of adsorption isotherms for a deformable adsorbent both from the classical Langmuir adsorption isotherms of a two-component gas and from the adsorption isotherms of a one-component gas taking into account variations in adsorption properties of the adsorbent in adsorption is obtained. We establi...

Ionogenic adsorbents based on local raw materials for radiation protection

International Nuclear Information System (INIS)

Isobaev, M.D.; Davlatnazarova, M.; Turdialiev, M.Z.; Abdullayev, T.H.; Pulatov, E.H.

2012-01-01

The successful management of uranium wastes and creating the conditions for effective rehabilitation activities require special adsorbents capable of holding on the surface complexes, including radioactive elements. Currently tested and have shown promising synthetic adsorbents based pitted apricot fruits and other fruit plants. This report presents data for the establishment of ionic type available adsorbents based on Tajikistan coal. As the base for the creation of this type of adsorbent were taken the coal of the 'Ziddi' deposits. As follows from our data on the chemical composition, the studied coals contain more than 20% of the ash. According to the available literature theses ashes contains various minerals compositions that can form the adsorbent's active surface. Thus, the model for this type of activated carbon can serve as a mixture of zeolite, ion exchange resins and activated carbon itself.

Performance of adsorbent-embedded heat exchangers using binder-coating method

KAUST Repository

Li, Ang

2016-01-01

The performance of adsorption (AD) chillers or desalination cycles is dictated by the rates of heat and mass transfer of adsorbate in adsorbent-packed beds. Conventional granular-adsorbent, packed in fin-tube heat exchangers, suffered from poor heat transfer in heating (desorption) or cooling (adsorption) processes of the batch-operated cycles, with undesirable performance parameters such as higher footprint of plants, low coefficient of performance (COP) of AD cycles and higher capital cost of the machines. The motivation of present work is to mitigate the heat and mass "bottlenecks" of fin-tube heat exchangers by using a powdered-adsorbent cum binder coated onto the fin surfaces of exchangers. Suitable adsorbent-binder pairs have been identified for the silica gel adsorbent with pore surface areas up to 680 m2/g and pore diameters less than 6 nm. The parent silica gel remains largely unaffected despite being pulverized into fine particles of 100 μm, and yet maintaining its water uptake characteristics. The paper presents an experimental study on the selection and testing processes to achieve high efficacy of adsorbent-binder coated exchangers. The test results indicate 3.4-4.6 folds improvement in heat transfer rates over the conventional granular-packed method, resulting a faster rate of water uptake by 1.5-2 times on the suitable silica gel type. © 2015 Elsevier Ltd. All rights reserved.

Excited-State N2 Dissociation Pathway on Fe-Functionalized Au.

Science.gov (United States)

Martirez, John Mark P; Carter, Emily A

2017-03-29

Localized surface plasmon resonances (LSPRs) offer the possibility of light-activated chemical catalysis on surfaces of strongly plasmonic metal nanoparticles. This technology relies on lower-barrier bond formation and/or dissociation routes made available through energy transfer following the eventual decay of LSPRs. The coupling between these decay processes and a chemical trajectory (nuclear motion, charge-transfer, intersystem crossing, etc.) dictates the availability of these alternative (possibly lower barrier) excited-state channels. The Haber-Bosch method of NH 3 synthesis from N 2 and H 2 is notoriously energy intensive. This is due to the difficulty of N 2 dissociation despite the overall reaction being thermodynamically favorable at ambient temperatures and pressures. LSPRs may provide means to improve the kinetics of N 2 dissociation via induced resonance electronic excitation. In this work, we calculate, via embedded n-electron valence second-order perturbation theory within the density functional embedding theory, the excited-state potential energy surfaces for dissociation of N 2 on an Fe-doped Au(111) surface. This metal alloy may take advantage simultaneously of the strong LSPR of Au and the catalytic activity of Fe toward N 2 dissociation. We find the ground-state dissociation activation energy to be 4.74 eV/N 2 , with Fe as the active site on the surface. Consecutive resonance energy transfers (RETs) may be accessed due to the availability of many electronically excited states with intermediate energies arising from the metal surface that may couple to states induced by the Fe-dopant and the adsorbate molecule, and crossing between excited states may effectively lower the dissociation barrier to 1.33 eV. Our work illustrates that large energetic barriers, prohibitive toward chemical reaction, may be overcome through multiple RETs facilitating an otherwise difficult chemical process.

X-ray emission spectroscopy applied to glycine adsorbed on Cu(110): An atom and symmetry projected view

Energy Technology Data Exchange (ETDEWEB)

Hasselstroem, J.; Karis, O.; Weinelt, M. [Uppsala Univ. (Sweden)] [and others

1997-04-01

When a molecule is adsorbed on a metal surface by chemical bonding new electronic states are formed. For noble and transition metals these adsorption-induced states overlap with the much more intense metal d-valence band, making them difficult to probe by for instance direct photoemission. However, it has recently been shown that X-ray emission spectroscopy (XES) can be applied to adsorbate systems. Since the intermediate state involves a core hole, this technique has the power to project out the partial density of states around each atomic site. Both the excitation and deexcitation processes are in general governed by the dipole selection rules. For oriented system, it is hence possible to obtain a complete separation into 2p{sub x}, 2p{sub y} and 2p{sub z} contributions using angular resolved measurements. The authors have applied XES together with other core level spectroscopies to glycine adsorption on Cu(110). Glycine (NH{sub 2}CH{sub 2}COOH) is the smallest amino acid and very suitable to study by core level spectroscopy since it has several functional groups, all well separated in energy by chemical shifts. Its properties are futhermore of biological interest. In summary, the authors have shown that it is possible to apply XES to more complicated molecular adsorbates. The assignment of different electronic states is however not as straight forward as for simple diatomic molecules. For a complete understanding of the redistribution and formation of new electronic states associated with the surface chemical bond, experimental data must be compared to theoretical calculations.

Laser amplification in excited dielectrics

Science.gov (United States)

Winkler, Thomas; Haahr-Lillevang, Lasse; Sarpe, Cristian; Zielinski, Bastian; Götte, Nadine; Senftleben, Arne; Balling, Peter; Baumert, Thomas

2018-01-01

Wide-bandgap dielectrics such as glasses or water are transparent at visible and infrared wavelengths. This changes when they are exposed to ultrashort and highly intense laser pulses. Different interaction mechanisms lead to the appearance of various transient nonlinear optical phenomena. Using these, the optical properties of dielectrics can be controlled from the transparent to the metal-like state. Here we expand this range by a yet unexplored mechanism in excited dielectrics: amplification. In a two-colour pump-probe experiment, we show that a 400 nm femtosecond laser pulse is coherently amplified inside an excited sapphire sample on a scale of a few micrometres. Simulations strongly support the proposed two-photon stimulated emission process, which is temporally and spatially controllable. Consequently, we expect applications in all fields that demand strongly localized amplification.

Toward an effective adsorbent for polar pollutants: Formaldehyde adsorption by activated carbon

International Nuclear Information System (INIS)

Lee, Kyung Jin; Miyawaki, Jin; Shiratori, Nanako; Yoon, Seong-Ho; Jang, Jyongsik

2013-01-01

Highlights: • Activated carbon fiber with mild activation condition is useful as adsorbent for polar pollutants. • Diverse variations are investigated for developing an effective adsorbent. • Surface functional group is the most important factor for capacity as a adsorbent. • Surface functional groups on ACFs are investigated using micro-ATR FTIR. -- Abstract: Due to increasing concerns about environmental pollutants, the development of an effective adsorbent or sensitive sensor has been pursued in recent years. Diverse porous materials have been selected as promising candidates for detecting and removing harmful materials, but the most appropriate pore structure and surface functional groups, both important factors for effective adsorbency, have not yet been fully elucidated. In particular, there is limited information relating to the use of activated carbon materials for effective adsorbent of specific pollutants. Here, the pore structure and surface functionality of polyacrylonitrile-based activated carbon fibers were investigated to develop an efficient adsorbent for polar pollutants. The effect of pore structure and surface functional groups on removal capability was investigated. The activated carbons with higher nitrogen content show a great ability to absorb formaldehyde because of their increased affinity with polar pollutants. In particular, nitrogen functional groups that neighbor oxygen atoms play an important role in maximizing adsorption capability. However, because there is also a similar increase in water affinity in adsorbents with polar functional groups, there is a considerable decrease in adsorption ability under humid conditions because of preferential adsorption of water to adsorbents. Therefore, it can be concluded that pore structures, surface functional groups and the water affinity of any adsorbent should be considered together to develop an effective and practical adsorbent for polar pollutants. These studies can provide vital

The development of an adsorbent for corrosion products in high-temperature water

Energy Technology Data Exchange (ETDEWEB)

Kim, Yong Ik; Sung, Ki Woung; Kim, Kwang Rag; Kim, Yu Hwan; Koo, Jae Hyoo [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1996-08-01

In order to use as adsorbent for removal of the soluble corrosion products, mainly Co{sup 60} under PWR reactor coolant conditions (300 deg C, 160 kg/cm{sup 2}), stable ZrO{sub 2} adsorbent was prepared using sol-gel process from zirconyl nitrate, AlO adsorbent was prepared by hydrolysis of aluminum isopropoxide, and titanium tetraisopropoxide, respectively. The prepared adsorbents were calcined at various temperature and analyzed by physical properties and the Co{sup 2+} adsorption capacity. And it was shown that the Co{sup 2+} adsorption capacity of the TiO{sub 2}-Al{sub 2}O{sub 3} adsorbents were found to have larger than that of ZrO{sub 2} and Al{sub 2}O{sub 3} adsorbents in high-temperature water. ZrO{sub 2}, Al{sub 2}O{sub 3} and TiO{sub 2}-Al{sub 2}O{sub 3} adsorbents were found to be suitable high-temperature adsorbents for the removal of dissolved corrosion products, mainly Co in PWR reactor coolant conditions. 15 tabs., 51 figs., 55 refs. (Author).

Removal of arsenic from water using nano adsorbents and challenges: A review.

Science.gov (United States)

Lata, Sneh; Samadder, S R

2016-01-15

Many researchers have used nanoparticles as adsorbents to remove water pollutants including arsenic after modifying the properties of nanoparticles by improving reactivity, biocompatibility, stability, charge density, multi-functionalities, and dispersibility. For arsenic removal, nano adsorbents emerged as the potential alternatives to existing conventional technologies. The present study critically reviewed the past and current available information on the potential of nano adsorbents for arsenic removal from contaminated water and the challenges involved in that. The study discussed the separation and regeneration techniques of nano adsorbents and the performance thereof. The study evaluated the adsorption efficiency of the various nanoparticles based on size of nanoparticles, types of nano adsorbents, method of synthesis, separation and regeneration of the nano adsorbents. The study found that more studies are required on suitable holding materials for the nano adsorbents to improve the permeability and to make the technology applicable at the field condition. The study will help the readers to choose suitable nanomaterials and to take up further research required for arsenic removal using nano adsorbents. Copyright © 2015 Elsevier Ltd. All rights reserved.

Design and performance prediction of a new generation adsorption chiller using composite adsorbent

International Nuclear Information System (INIS)

Gong, L.X.; Wang, R.Z.; Xia, Z.Z.; Chen, C.J.

2011-01-01

Research highlights: → Composite adsorbent 'employing lithium chloride in silica gel' and water as working pair. → A new type adsorbent bed is used to accommodate the composite adsorbent. → A dynamic model of the adsorption chiller is built. → The coefficient of performance (COP) and the cooling capacity will be improved. -- Abstract: This paper presents a novel adsorption chiller using composite adsorbent 'employing lithium chloride in silica gel' as adsorbent and water as adsorbate. A new type adsorbent bed is used to accommodate the composite adsorbent. The mass recovery between two adsorbent beds usually results in the adsorbate unbalance. So a novel auto water makeup unite is used to solve the problem. A dynamic model of the adsorption chiller is built based on the adsorption isotherms to predict the performance. The simulation result shows that the coefficient of performance (COP) and the cooling capacity will increase by using this new composite adsorbent. When the temperatures of hot water inlet, cooling water inlet, and chilled water inlet are 363, 303 and 293 K, COP will be 0.43, and the cooling capacity will be 5.295 kW. Also operation strategy is optimized. Different temperatures of hot water inlet, cooling water inlet and chilling water inlet will result in different COP and cooling capacity.

Carbon/Attapulgite Composites as Recycled Palm Oil-Decoloring and Dye Adsorbents

Directory of Open Access Journals (Sweden)

Guangyan Tian

2018-01-01

Full Text Available Activated clay minerals have been widely used in the edible oil refining industry for decolorization of crude oil by adsorption, and so far many methods have been used to improve their decolorization efficiency. Herein, we successfully prepared a series of carbon/attapulgite (C/APT composite adsorbents by a one-step in-situ carbonization process with natural starch (St as the carbon source. It has been revealed that the adsorbent had better decolorization efficiency for crude palm oil than acid-activated APT. However, more than a million tons of decolorized waste is produced every year in the oil-refining industry, which was often treated as solid waste and has not yet been reutilized effectively. In order to explore a viable method to recycle and reuse the decolorant, the waste decolorant was further prepared into new C/APT adsorbents for the removal of dyes from wastewater, and then the dyes adsorbed on the adsorbent were used as the carbon sources to produce new C/APT adsorbents by a cyclic carbonization process. The results showed that the adsorbents prepared from the decolorized waste could remove more than 99.5% of the methylene blue (MB, methyl violet (MV, and malachite green (MG dyes from the simulated wastewater with the dye concentration of 200 mg/L, and the C/APT–Re adsorbent consecutively regenerated five times using the adsorbed dyes as a carbon source still exhibit good adsorption efficiency for dyes. As a whole, this process opens a new avenue to develop efficient decolorants of palm oil and achieves recyclable utilization of decolored waste.

Hyperon excitation in nuclear coulomb field

International Nuclear Information System (INIS)

Vanyashin, A.V.; Nikitin, Yu.P.; Shan'gin, A.A.

1981-01-01

A possibility is studied to measure radiative decay partial widths from the 3/2 + decuplet hyperon resonances by means of the Coulomb excitation method of the octet hyperons. The expected contributions from the strong and electromagnetic interactions in the coherence range to the hyperon excitation cross sections on heavy nuclei and on the 4 He nucleus are estimated. The particle angular distributions in the reactions Σ-+A→Σ-(1385)+A and Λ+A→Σ 0 (1385)+A are analysed in order to determine the energy range where the background conditions are the most favorable to extract the electromagnetic mechanism of the hyperon excitation [ru

Initial mechanisms for the decomposition of electronically excited energetic materials: 1,5′-BT, 5,5′-BT, and AzTT

International Nuclear Information System (INIS)

Yuan, Bing; Yu, Zijun; Bernstein, Elliot R.

2015-01-01

Decomposition of nitrogen-rich energetic materials 1,5′-BT, 5,5′-BT, and AzTT (1,5′-Bistetrazole, 5,5′-Bistetrazole, and 5-(5-azido-(1 or 4)H-1,2,4-triazol-3-yl)tetrazole, respectively), following electronic state excitation, is investigated both experimentally and theoretically. The N 2 molecule is observed as an initial decomposition product from the three materials, subsequent to UV excitation, with a cold rotational temperature (<30 K). Initial decomposition mechanisms for these three electronically excited materials are explored at the complete active space self-consistent field (CASSCF) level. Potential energy surface calculations at the CASSCF(12,8)/6-31G(d) level illustrate that conical intersections play an essential role in the decomposition mechanism. Electronically excited S 1 molecules can non-adiabatically relax to their ground electronic states through (S 1 /S 0 ) CI conical intersections. 1,5′-BT and 5,5′-BT materials have several (S 1 /S 0 ) CI conical intersections between S 1 and S 0 states, related to different tetrazole ring opening positions, all of which lead to N 2 product formation. The N 2 product for AzTT is formed primarily by N–N bond rupture of the –N 3 group. The observed rotational energy distributions for the N 2 products are consistent with the final structures of the respective transition states for each molecule on its S 0 potential energy surface. The theoretically derived vibrational temperature of the N 2 product is high, which is similar to that found for energetic salts and molecules studied previously

A potential low cost adsorbent for the removal of cationic dyes from aqueous solutions

Science.gov (United States)

Uddin, Md. Tamez; Rahman, Md. Arifur; Rukanuzzaman, Md.; Islam, Md. Akhtarul

2017-10-01

This study was aimed at using mango leaf powder (MLP) as a potential adsorbent for the removal of methylene blue (MB) from aqueous solutions. Characterization of the adsorbent was carried out with scanning electron microscopy, Fourier transform infrared spectroscopy, and nitrogen adsorption-desorption analysis. The pH at the point of zero charge of the adsorbent was determined by titration method and was found a value to be 5.6 ± 0.2. Batch studies were performed to evaluate the influence of various experimental parameters like initial solution pH, contact time, initial concentration of dye and adsorbent dosage on the removal of MB. An adsorption-desorption study was carried out resulting the mechanism of adsorption was carried out by electrostatic force of attraction. The adsorption equilibrium time required for the adsorption of MB on MLP was almost 2 h and 85 ± 5% of the total amount of dye uptake was found to occur in the first rapid phase (30 min). The Langmuir and Freundlich isotherm models were used for modeling the adsorption equilibrium. The experimental equilibrium data could be well interpreted by Langmuir isotherm with maximum adsorption capacity of 156 mg/g. To state the sorption kinetics, the fits of pseudo-first-order and pseudo-second-order kinetic models were investigated. It was obtained that the adsorption process followed the pseudo-second-order rate kinetics. The above findings suggest that MLP can be effectively used for decontamination of dye containing wastewater.

The application of Fe–Mn hydrous oxides based adsorbent for removing selenium species from water

KAUST Repository

Szlachta, Małgorzata

2013-02-01

In this study, the adsorptive removal of selenium(IV) and selenium(VI) from water by a newly developed ion exchange adsorbent, based on Fe(III) and Mn(III) hydrous oxides, was examined. This study was conducted to determine the influence of various operating parameters, such as initial anion concentration, contact time, adsorbent dose, pH, solution temperature, and the presence of competitive anions, on the treatment performance. The high Se(IV) adsorptive capacity of the adsorbent (up to 41.02. mg/g at pH 4) was due to its high affinity for selenite, as reflected in the fast rate of uptake (batch studies) and an efficient long-term removal (column experiments). Although adsorption of anions traditionally decreases as pH increases, the mixed adsorbent was capable of purifying large volumes of Se(IV)-containing water (at pH 7) to reach concentrations lower than 10 μg/L, which meets the European Commission standards. The presence of sulphate and carbonate did not influence Se(IV) adsorption. However, high phosphate and silicate concentrations may have decreased the removal efficiency of Se(IV). Data from the batch and column adsorption experiments were fitted with a number of approved models, which revealed the adsorption mechanism and allowed for a comparison of the results. © 2012 Elsevier B.V.

Excitation of Stellar Pulsations

DEFF Research Database (Denmark)

Houdek, G.

2012-01-01

In this review I present an overview of our current understanding of the physical mechanisms that are responsible for the excitation of pulsations in stars with surface convection zones. These are typically cooler stars such as the δ Scuti stars, and stars supporting solar-like oscillations....

An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid

Energy Technology Data Exchange (ETDEWEB)

Wang, Lingling, E-mail: lasier_wang@hotmail.com [College of Chemical Engineering and Materials, Quanzhou Normal University, Quanzhou 362000, Fujian (China); Environmental Engineering and Science Program, 705 Engineering Research Center, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); Han, Changseok [ORISE Post-doctoral Fellow, The U.S. Environmental Protection Agency, ORD, NRMRL, STD, CPB, 26 W. Martin Luther King Jr. Drive, Cincinnati, OH 45268 (United States); Nadagouda, Mallikarjuna N. [The U.S. Environmental Protection Agency, ORD, NRMRL, WSWRD, WQMB, 26 W. Martin Luther King Jr. Drive, Cincinnati, OH 45268 (United States); Dionysiou, Dionysios D., E-mail: dionysios.d.dionysiou@uc.edu [Environmental Engineering and Science Program, 705 Engineering Research Center, University of Cincinnati, Cincinnati, OH 45221-0012 (United States); Nireas-International Water Research Centre, School of Engineering, University of Cyprus, PO Box 20537, 1678, Nicosia (Cyprus)

2016-08-05

Highlights: • An innovative adsorbent was successfully synthesized to remove humic acid. • The adsorbent possessed high adsorption capacity for humic acid. • The adsorption capacity remarkably increased after an acid modification. • The adsorption capacity was proportional to the amount of ZnO coated on zeolite. • Electrostatic interactions are a major factor at the first stage of the process. - Abstract: Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO{sub 3}){sub 2}·6H{sub 2}O functionalization of zeolite 4A. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The synthesized materials were characterized by porosimetry analysis, scanning electron microscopy, X-Ray diffraction analysis, and high resolution transmission electron microscopy. The maximum adsorption capacity of the adsorbents at 21 ± 1 °C was about 60 mgC g{sup −1}. The results showed that the positive charge density of ZnO-coated zeolite adsorbents was proportional to the amount of ZnO coated on zeolite and thus, ZnO-coated zeolite adsorbents exhibited a greater affinity for negatively charged ions. Furthermore, the adsorption capacity of ZnO-coated zeolite adsorbents increased markedly after acid modification. Adsorption experiments demonstrated ZnO-coated zeolite adsorbents possessed high adsorption capacity to remove HA from aqueous solutions mainly due to strong electrostatic interactions between negative functional groups of HA and the positive charges of ZnO-coated zeolite adsorbents.

An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid

International Nuclear Information System (INIS)

Wang, Lingling; Han, Changseok; Nadagouda, Mallikarjuna N.; Dionysiou, Dionysios D.

2016-01-01

Highlights: • An innovative adsorbent was successfully synthesized to remove humic acid. • The adsorbent possessed high adsorption capacity for humic acid. • The adsorption capacity remarkably increased after an acid modification. • The adsorption capacity was proportional to the amount of ZnO coated on zeolite. • Electrostatic interactions are a major factor at the first stage of the process. - Abstract: Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO_3)_2·6H_2O functionalization of zeolite 4A. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The synthesized materials were characterized by porosimetry analysis, scanning electron microscopy, X-Ray diffraction analysis, and high resolution transmission electron microscopy. The maximum adsorption capacity of the adsorbents at 21 ± 1 °C was about 60 mgC g"−"1. The results showed that the positive charge density of ZnO-coated zeolite adsorbents was proportional to the amount of ZnO coated on zeolite and thus, ZnO-coated zeolite adsorbents exhibited a greater affinity for negatively charged ions. Furthermore, the adsorption capacity of ZnO-coated zeolite adsorbents increased markedly after acid modification. Adsorption experiments demonstrated ZnO-coated zeolite adsorbents possessed high adsorption capacity to remove HA from aqueous solutions mainly due to strong electrostatic interactions between negative functional groups of HA and the positive charges of ZnO-coated zeolite adsorbents.

Exploiting large-pore metal-organic frameworks for separations through entropic molecular mechanisms

NARCIS (Netherlands)

Torres-Knoop, A.; Dubbeldam, D.

2015-01-01

We review the molecular mechanisms behind adsorption and the separations of mixtures in metal-organic frameworks and zeolites. Separation mechanisms can be based on differences in the affinity of the adsorbate with the framework and on entropic effects. To develop next-generation adsorbents, the

Hyperspherical approach to double-electron excitation of He by fast-ion impact

International Nuclear Information System (INIS)

Moribayashi, K.; Hino, K.; Matsuzawa, M.; Kimura, M.

1991-01-01

Double-electron-excitation processes of He atoms by proton, antiproton, and C 6+ -ion impact have been theoretically investigated using the second-order Born approximation and the close-coupling method in the energy regime of MeV/u. The semiclassical impact-parameter method with a straight-line-trajectory approximation is employed to describe the collision processes. Hyperspherical wave functions are adopted to take full account of the strongly correlated motion of two atomic electrons in He. For proton and antiproton impact, it is found that the first-order mechanism dominates for excitation to the (2s2p) 1 Po excited state, while the second-order processes play a significant role in excitation to the (2s2s) 1 Se, (2p2p) 1 Se, and (2p2p) 1 De excited states at a few MeV/u. It should be noted that the doubly excited (2s2p) 1 Po state plays an important role as an intermediate state in these second-order processes in addition to the singly excited 1s2p 1 Po state. It is also found that the difference for the double-electron-excitation processes by proton impact and by antiproton impact is much smaller than that for the double-ionization processes in this energy range. For the C 6+ -ion impact, higher-order mechanisms play more important roles at a few MeV/u. The excitation mechanism is also discussed based on the classification scheme of the correlation quantum numbers, which enables us to obtain a more direct physical insight into the collision mechanism

Kinetics of the homogeneous exchange of alpha-lactalbumin adsorbed on titanium oxide surface.

Science.gov (United States)

Bentaleb, A; Haïkel, Y; Voegel, J C; Schaaf, P

1998-06-05

The homogeneous exchange process whereby alpha-lactalbumine molecules adsorbed on hydrophilic titanium oxide particles are replaced by alpha-lactalbumine molecules in solution has been investigated by means of a 125I radio-labeling technique, alpha-lactalbumine is a compact and highly negatively charged protein, making this study complementary to previous work devoted to the general understanding of the exchange mechanisms of adsorbed proteins on solid surfaces. The isotherm of alpha-lactalbumine exhibits bimodal adsorption shape, and the exchange process whereby adsorbed proteins are replaced by new incoming ones from the bulk solution has been studied at both the upper and the lower plateau of the isotherm. In the upper plateau the exchange process was found to be of first order with respect to the bulk molecules, and the release rate constant was equal to 0.914 L. mol-1.s-1. This behavior is identical to what has been observed with other proteinic systems. In the lower plateau domain, in contrast, the protein release process is independent of the concentration of proteins in the bulk, but the release rates are higher than the pure desorption rates. This constitutes, to our knowledge, a behavior that never before has been observed and that remains to be explained.

Lotus Dust Mitigation Coating and Molecular Adsorber Coating

Science.gov (United States)

O'Connor, Kenneth M.; Abraham, Nithin S.

2015-01-01

NASA Goddard Space Flight Center has developed two unique coating formulations that will keep surfaces clean and sanitary and contain contaminants.The Lotus Dust Mitigation Coating, modeled after the self-cleaning, water-repellant lotus leaf, disallows buildup of dust, dirt, water, and more on surfaces. This coating, has been successfully tested on painted, aluminum, glass, silica, and some composite surfaces, could aid in keeping medical assets clean.The Molecular Adsorber Coating is a zeolite-based, sprayable molecular adsorber coating, designed to prevent outgassing in materials in vacuums. The coating works well to adsorb volatiles and contaminates in manufacturing and processing, such as in pharmaceutical production. The addition of a biocide would also aid in controlling bacteria levels.

Catalase-like activity studies of the manganese(II) adsorbed zeolites

Science.gov (United States)

Ćiçek, Ekrem; Dede, Bülent

2013-12-01

Preparation of manganese(II) adsorbed on zeolite 3A, 4A, 5A. AW-300, ammonium Y zeolite, organophilic, molecular sieve and catalase-like enzyme activity of manganese(II) adsorbed zeolites are reported herein. Firstly zeolites are activated at 873 K for two hours before contact manganese(II) ions. In order to observe amount of adsorption, filtration process applied for the solution. The pure zeolites and manganese(II) adsorbed zeolites were analysed by FT-IR. As a result according to the FT-IR spectra, the incorporation of manganese(II) cation into the zeolite structure causes changes in the spectra. These changes are expected particularly in the pseudolattice bands connected with the presence of alumino and silicooxygen tetrahedral rings in the zeolite structure. Furthermore, the catalytic activities of the Mn(II) adsorbed zeolites for the disproportionation of hydrogen peroxide were investigated in the presence of imidazole. The Mn(II) adsorbed zeolites display efficiency in the disproportion reactions of hydrogen peroxide, producing water and dioxygen in catalase-like activity.

Kinetic studies of adsorption in the bioethanol dehydration using polyvinyl alcohol, zeolite and activated carbon as adsorbent

Science.gov (United States)

Laksmono, J. A.; Pratiwi, I. M.; Sudibandriyo, M.; Haryono, A.; Saputra, A. H.

2017-11-01

Bioethanol is considered as the most promising alternative fuel in the future due to its abundant renewable sources. However, the result of bioethanol production process using fermentation contains 70% v/v, and it still needs simultaneous purification process. One of the most energy-efficient purification methods is adsorption. Specifically, the rate of adsorption is an important factor for evaluating adsorption performance. In this work, we have conducted an adsorption using polyvinyl alcohol (PVA), zeolite and activated carbon as promising adsorbents in the bioethanol dehydration. This research aims to prove that PVA, zeolite, activated carbon is suitable to be used as adsorbent in bioethanol dehydration process through kinetics study and water adsorption selectivity performance. According to the results, PVA, zeolite and activated carbon are the potential materials as adsorbents in the bioethanol dehydration process. The kinetics study shows that 30°C temperature gave the optimum adsorption kinetics rate for PVA, zeolite, and activated carbon adsorbents which were 0.4911 min-1; 0.5 min-1; and 1.1272 min-1 respectively. In addition, it also shows that the activated carbon performed as a more potential adsorbent due to its higher pore volume and specific surface area properties. Based on the Arrhenius equation, the PVA works in the chemisorption mechanism, meanwhile zeolite and activated carbon work in the physisorption system as shown in the value of the activation energy which are 51.43 kJ/mole; 8.16 kJ/mole; and 20.30 kJ/mole. Whereas the water to ethanol selectivity study, we discover that zeolite is an impressive adsorbent compared to the others due to the molecular sieving characteristic of the material.

Recovery of iron oxides from acid mine drainage and their application as adsorbent or catalyst.

Science.gov (United States)

Flores, Rubia Gomes; Andersen, Silvia Layara Floriani; Maia, Leonardo Kenji Komay; José, Humberto Jorge; Moreira, Regina de Fatima Peralta Muniz

2012-11-30

Iron oxide particles recovered from acid mine drainage represent a potential low-cost feedstock to replace reagent-grade chemicals in the production of goethite, ferrihydrite or magnetite with relatively high purity. Also, the properties of iron oxides recovered from acid mine drainage mean that they can be exploited as catalysts and/or adsorbents to remove azo dyes from aqueous solutions. The main aim of this study was to recover iron oxides with relatively high purity from acid mine drainage to act as a catalyst in the oxidation of dye through a Fenton-like mechanism or as an adsorbent to remove dyes from an aqueous solution. Iron oxides (goethite) were recovered from acid mine drainage through a sequential precipitation method. Thermal treatment at temperatures higher than 300 °C produces hematite through a decrease in the BET area and an increase in the point of zero charge. In the absence of hydrogen peroxide, the solids adsorbed the textile dye Procion Red H-E7B according to the Langmuir model, and the maximum amount adsorbed decreased as the temperature of the thermal treatment increased. The decomposition kinetics of hydrogen peroxide is dependent on the H(2)O(2) concentration and iron oxides dosage, but the second-order rate constant normalized to the BET surface area is similar to that for different iron oxides tested in this and others studies. These results indicate that acid mine drainage could be used as a source material for the production of iron oxide catalysts/adsorbents, with comparable quality to those produced using analytical-grade reagents. Copyright © 2012 Elsevier Ltd. All rights reserved.

Excitation in the radiation chemistry of inorganic gases

International Nuclear Information System (INIS)

Willis, C.; Boyd, A.W.

1976-01-01

Gas phase radiation chemistry yield data and electron impact cross-section data are used to derive excitation mechanisms and to discuss the role of excited states in the radiation chemistry of O 2 , N 2 , N 2 O, CO, CO 2 , H 2 S, H 2 O and NH 3 . For each of these systems available cross-sections for ionization and neutral excitation are listed, together with relevant reaction rate data and a summary of the radiation chemistry studies at both high and low dose rates. In general, fairly complete mechanisms are derived and further tested by energy balance calculations. In order to present as complete a picture as possible, a summary of rates and products of ion-neutralization reactions is given at the end of the paper. (author)

Removal of Ni(II from aqueous solution using leaf, bark and seed of Moringa stenopetala adsorbents

Directory of Open Access Journals (Sweden)

A. A. Mengistie

2013-04-01

Full Text Available The present study investigates the possibility of using leaf, bark and seed of Moringa stenopetala as alternative adsorbents for removal of Ni(II from aqueous solutions. The optimum adsorption conditions for removal of Ni(II were found to be 30, 20 and 50 mg/L initial concentration, 1.5, 2 and 2.5 g adsorbent dose, 250, 250 and 300 rpm agitation speed, 90, 120 and 90 min contact time, 40, 30 and 23 oC temperature and pH of 5, 6 and 6 using leaf, bark and seed as adsorbent, respectively. At optimum experimental conditions the percent adsorption of synthetic wastewater sample was found to be 93.90, 96.25 and 97.50 for leaf, bark and seed, respectively. The tested experimental data best fits to pseudo-second order (R2 > 0.98 than pseudo-first order, Elovich and intraparticle diffusion kinetic models indicating rate limiting step to be chemisorption. It also fits to Langmuir (R2 > 0.895 using adsorbate variation and also R2 > 0.998 using both time and temperature variation data than Freundlich, Temkin and D-R isotherm models. D-R isotherm and thermodynamic study reveals formation of physical adsorption. Hence the adsorption mechanism could be regarded as physico-chemical adsorption process. The adsorption results of industrial wastewater also reveal that for removal of nickel 83% and 85% was obtained using bark and seed adsorbents, respectively. The new method of adsorption developed in this study is cheap, fast and environmental friendly.DOI: http://dx.doi.org/10.4314/bcse.v27i1.4

Black Sprayable Molecular Adsorber Coating

Data.gov (United States)

National Aeronautics and Space Administration — The main objective of this technology project is to develop, optimize, and flight qualify a black version of the molecular adsorber coating and a conductive version...

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.

Condition of granulating titanium-activated carbon composite adsorbent and its adsorption for uranium

International Nuclear Information System (INIS)

Miyai, Yoshitaka; Kitamura, Takao; Katoh, Shunsaku; Miyazaki, Hidetoshi

1979-01-01

The powdery titanium-activated carbon composite adsorbent was granulated, and the strength and uranium adsorptivity of the granulated adsorbent were studied in relation to its granulating condition. By use of polyvinylalcohol (PVA) with degree of polymerization above 2,000 as binder, the granular adsorbent with as much the same strength as commercial granular activated carbon was obtained. Addition of PVA did not affect the amount of adsorbed uranium in equilibrium, but decreased the adsorption rate. Effect of granule size between 2-5 mm on the uranium adsorption rate was that the uranium adsorption rate changed proportionally to surface area of assumed sphere. As a test for practical use, 5 times repetitions of adsorption and desorption were carried out on the same granular adsorbent. During this repetition the adsorbent containing formalized PVA revealed smaller weight loss than non-treated adsorbent. The amount of adsorbed uranium decreased with increasing repetition times, and reason of this was discussed. (author)

Adsorption of uranium on adsorbents produced from used tires

International Nuclear Information System (INIS)

Mahramanlioglu, M.

2003-01-01

Potential use of adsorbents produced from used tires for the removal of uranium from aqueous solutions is investigated. Two different adsorbents were used including char and activated carbon produced from used tires. The surface area was larger on activated carbon. Adsorption experiments were carried out as a function of time, adsorbent concentration, pH and initial concentration of uranium. The adsorption kinetics was found to follow the Lagergren equation. The rate constants of intraparticle diffusion and mass transfer coefficients were calculated. It was shown that the equilibrium data could be fitted by the Langmuir and Freundlich equations. The adsorption of uranium in the presence of different cations were also studied and the results were correlated with the ionic potential of the cations. It was demonstrated that the activated carbon produced from used tires can be considered as an adsorbent that has a commercial potential for uranium removal. (author)

Inner-shell excitation of alkali-metal atoms

International Nuclear Information System (INIS)

Tiwary, S.N.

1987-06-01

Inner-shell excitation of alkali-metal atoms, which leads to auto-ionization, is reviewed. The validity of quantum mechanical approximation is analyzed and the importance of exchange and correlation is demonstrated. Basic difficulties in making accurate calculations for inner-shell excitation process are discussed. Suggestions are made for further study of inner-shell process in atoms and ions. (author). 26 refs, 4 figs, 1 tab

Waste metal hydroxide sludge as adsorbent for a reactive dye.

Science.gov (United States)

Santos, Sílvia C R; Vílar, Vítor J P; Boaventura, Rui A R

2008-05-30

An industrial waste sludge mainly composed by metal hydroxides was used as a low-cost adsorbent for removing a reactive textile dye (Remazol Brilliant Blue) in solution. Characterization of this waste material included chemical composition, pH(ZPC) determination, particle size distribution, physical textural properties and metals mobility under different pH conditions. Dye adsorption equilibrium isotherms were determined at 25 and 35 degrees C and pH of 4, 7 and 10 revealing reasonably fits to Langmuir and Freundlich models. At 25 degrees C and pH 7, Langmuir fit indicates a maximum adsorption capacity of 91.0mg/g. An adsorptive ion-exchange mechanism was identified from desorption studies. Batch kinetic experiments were also conducted at different initial dye concentration, temperature, adsorbent dosage and pH. A pseudo-second-order model showed good agreement with experimental data. LDF approximation model was used to estimate homogeneous solid diffusion coefficients and the effective pore diffusivities. Additionally, a simulated real effluent containing the selected dye, salts and dyeing auxiliary chemicals, was also used in equilibrium and kinetic experiments and the adsorption performance was compared with aqueous dye solutions.

Separation of atmospheric, oceanic and hydrological polar motion excitation mechanisms based on a combination of geometric and gravimetric space observations

Science.gov (United States)

Göttl, F.; Schmidt, M.; Seitz, F.; Bloßfeld, M.

2015-04-01

The goal of our study is to determine accurate time series of geophysical Earth rotation excitations to learn more about global dynamic processes in the Earth system. For this purpose, we developed an adjustment model which allows to combine precise observations from space geodetic observation systems, such as Satellite Laser Ranging (SLR), Global Navigation Satellite Systems, Very Long Baseline Interferometry, Doppler Orbit determination and Radiopositioning Integrated on Satellite, satellite altimetry and satellite gravimetry in order to separate geophysical excitation mechanisms of Earth rotation. Three polar motion time series are applied to derive the polar motion excitation functions (integral effect). Furthermore we use five time variable gravity field solutions from Gravity Recovery and Climate Experiment to determine not only the integral mass effect but also the oceanic and hydrological mass effects by applying suitable filter techniques and a land-ocean mask. For comparison the integral mass effect is also derived from degree 2 potential coefficients that are estimated from SLR observations. The oceanic mass effect is also determined from sea level anomalies observed by satellite altimetry by reducing the steric sea level anomalies derived from temperature and salinity fields of the oceans. Due to the combination of all geodetic estimated excitations the weaknesses of the individual processing strategies can be reduced and the technique-specific strengths can be accounted for. The formal errors of the adjusted geodetic solutions are smaller than the RMS differences of the geophysical model solutions. The improved excitation time series can be used to improve the geophysical modeling.

Adsorptive removal of organics from aqueous phase by acid-activated coal fly ash: preparation, adsorption, and Fenton regenerative valorization of "spent" adsorbent.

Science.gov (United States)

Wang, Nannan; Hao, Linlin; Chen, Jiaqing; Zhao, Qiang; Xu, Han

2018-05-01

Raw coal fly ash was activated to an adsorbent by sulfuric acid impregnation. The activation condition, the adsorption capacity, and the regenerative valorization of the adsorbent were studied. The results show that the optimal preparation conditions of the adsorbent are [H 2 SO 4 ] = 1 mol L -1 , activation time = 30 min, the ratio of coal fly ash to acid = 1:20 (g:mL), calcination temperature = 100 °C. The adsorption of p-nitrophenol on the adsorbent accords with the pseudo-second-order kinetic equation and the adsorption rate constant is 0.089 g mg -1  min -1 . The adsorption on this adsorbent can be considered enough after 35 min, when the corresponding adsorption capacity is 1.07 mg g -1 (85.6% of p-nitrophenol removal). Compared with raw coal fly ash, the adsorbent has a stable adsorption performance at low pH range (pH = 1-6) and the adsorption of p-nitrophenol is an exothermic process. Ninety minutes is required for the regenerative valorization of saturated adsorbent by Fenton process. The regenerative valorization for this saturated adsorbent can reach 89% under the optimal proposed conditions (30 °C, pH = 3, [H 2 O 2 ] = 5.0 mmol L -1 , [Fe 2+ ] = 5.5 mmol L -1 ). Within 15 experimental runs, the adsorbent has a better and better stability with the increase of experimental runs. Finally, the mechanism of activating coal fly ash is proposed, being verified by the results of the SEM and BET test.

Excitation of lateral habenula neurons as a neural mechanism underlying ethanol-induced conditioned taste aversion.

Science.gov (United States)

Tandon, Shashank; Keefe, Kristen A; Taha, Sharif A

2017-02-15

The lateral habenula (LHb) has been implicated in regulation of drug-seeking behaviours through aversion-mediated learning. In this study, we recorded neuronal activity in the LHb of rats during an operant task before and after ethanol-induced conditioned taste aversion (CTA) to saccharin. Ethanol-induced CTA caused significantly higher baseline firing rates in LHb neurons, as well as elevated firing rates in response to cue presentation, lever press and saccharin taste. In a separate cohort of rats, we found that bilateral LHb lesions blocked ethanol-induced CTA. Our results strongly suggest that excitation of LHb neurons is required for ethanol-induced CTA, and point towards a mechanism through which LHb firing may regulate voluntary ethanol consumption. Ethanol, like other drugs of abuse, has both rewarding and aversive properties. Previous work suggests that sensitivity to ethanol's aversive effects negatively modulates voluntary alcohol intake and thus may be important in vulnerability to developing alcohol use disorders. We previously found that rats with lesions of the lateral habenula (LHb), which is implicated in aversion-mediated learning, show accelerated escalation of voluntary ethanol consumption. To understand neural encoding in the LHb contributing to ethanol-induced aversion, we recorded neural firing in the LHb of freely behaving, water-deprived rats before and after an ethanol-induced (1.5 g kg -1 20% ethanol, i.p.) conditioned taste aversion (CTA) to saccharin taste. Ethanol-induced CTA strongly decreased motivation for saccharin in an operant task to obtain the tastant. Comparison of LHb neural firing before and after CTA induction revealed four main differences in firing properties. First, baseline firing after CTA induction was significantly higher. Second, firing evoked by cues signalling saccharin availability shifted from a pattern of primarily inhibition before CTA to primarily excitation after CTA induction. Third, CTA induction reduced

Excitation of lateral habenula neurons as a neural mechanism underlying ethanol‐induced conditioned taste aversion

Science.gov (United States)

Keefe, Kristen A.; Taha, Sharif A.

2016-01-01

Key points The lateral habenula (LHb) has been implicated in regulation of drug‐seeking behaviours through aversion‐mediated learning.In this study, we recorded neuronal activity in the LHb of rats during an operant task before and after ethanol‐induced conditioned taste aversion (CTA) to saccharin.Ethanol‐induced CTA caused significantly higher baseline firing rates in LHb neurons, as well as elevated firing rates in response to cue presentation, lever press and saccharin taste.In a separate cohort of rats, we found that bilateral LHb lesions blocked ethanol‐induced CTA.Our results strongly suggest that excitation of LHb neurons is required for ethanol‐induced CTA, and point towards a mechanism through which LHb firing may regulate voluntary ethanol consumption. Abstract Ethanol, like other drugs of abuse, has both rewarding and aversive properties. Previous work suggests that sensitivity to ethanol's aversive effects negatively modulates voluntary alcohol intake and thus may be important in vulnerability to developing alcohol use disorders. We previously found that rats with lesions of the lateral habenula (LHb), which is implicated in aversion‐mediated learning, show accelerated escalation of voluntary ethanol consumption. To understand neural encoding in the LHb contributing to ethanol‐induced aversion, we recorded neural firing in the LHb of freely behaving, water‐deprived rats before and after an ethanol‐induced (1.5 g kg−1 20% ethanol, i.p.) conditioned taste aversion (CTA) to saccharin taste. Ethanol‐induced CTA strongly decreased motivation for saccharin in an operant task to obtain the tastant. Comparison of LHb neural firing before and after CTA induction revealed four main differences in firing properties. First, baseline firing after CTA induction was significantly higher. Second, firing evoked by cues signalling saccharin availability shifted from a pattern of primarily inhibition before CTA to primarily excitation after CTA

Determination of elastic mechanical characteristics of surface coatings from analysis of signals obtained by impulse excitation

Science.gov (United States)

Nyaguly, E.; Craştiu, I.; Deac, S.; Gozman-Pop, C.; Drăgănescu, G.; Bereteu, L.

2018-01-01

Most of the surface coatings are based on the synthetic polymers, which are substances composed from very large molecules that form tough, flexible, adhesive films when applied to surfaces. The other components of surface coverings materials are pigments that provide colour, opacity, gloss and other properties. Surface coatings are two-phase composite materials: constitute a polymer matrix on the one side, and on the other side of the pigments and additives dispersed in the matrix. Their role is not only aesthetically but also to ensure anticorrosive protection or even improve some mechanical properties of coated surfaces. In this paper it will follow, starting from the mechanical properties of the substrate, the metallic sheet in general, to determine the new properties of the assembly of substrate and the two coating layers, also the determination of mechanical properties of the layers. From the analysis of vibroacoustic signals obtained by the impulse excitation of the sample, one can determine the elasticity modulus. These results come to validate the results based on finite element analysis (FEA) of the same samples.

Nuclear excitations and reaction mechanisms

International Nuclear Information System (INIS)

Fallieros, S.; Levin, F.S.

1990-01-01

The main theme of this report is the study and interpretation of the sequence of events that occur during the collisions of nuclear particles. Some of the processes discussed in parts A and B involve short range interactions; others involve interactions of long range. In most of part A one of the particles in the initial or in the final state (or in both) is a photon, which serves as a probe of the second particle, which may be a nucleus, a proton, a pion or any other hadron. The complexity of the processes taking place during the collisions makes it necessary to simplify some aspects of the physical problem. This leads to the introduction of modals which are used to describe a limited number of features in as much detail as possible. The main interest is the understanding of the hadronic excitations which result from the absorption of a photon and the determination of the fundamental structure constants of the target particle. In part B, all the particles are hadrons. The purpose here is to develop and apply optimal quantal methods appropriate for describing the interacting systems. Of particular interest are three-particle collision systems in which the final state consists of three free particles. Part B also considers the process of nuclear fusion as catalyzed by bound muons

Preparation of metal adsorbents from chitin/chitosan by radiation technology

International Nuclear Information System (INIS)

Nguyen Van Suc; Nguyen Quoc Hien; Ngo Quang Huy; Thai My Phe; Dao Van Hoang; Nguyen Van Hung

2004-01-01

The methods of preparation of metal adsorbents basing on chitin/chitosan were developed. That include the adsorbent from chitin grafted with acrylic acid by different irradiation doses; the clinging chitosan gel beads; the coagulable solution and the chitosan composite filter. The process of metal adsorption for each adsorbent was studied as adsorption kinetic, isothermal adsorption. The results have been applied for removal of some elements as Hg, Pb, Cd, U, Cu, ect. in the wastewater. (NHA)

Using narrowband excitation to confirm that the S∗ state in carotenoids is not a vibrationally-excited ground state species

Science.gov (United States)

Jailaubekov, Askat E.; Song, Sang-Hun; Vengris, Mikas; Cogdell, Richard J.; Larsen, Delmar S.

2010-02-01

The hypothesis that S∗ is a vibrationally-excited ground-state population is tested and discarded for two carotenoid samples: β-carotene in solution and rhodopin glucoside embedded in the light harvesting 2 protein from Rhodopseudomonas acidophila. By demonstrating that the transient absorption signals measured in both systems that are induced by broadband (1000 cm -1) and narrowband (50 cm -1) excitation pulses are near identical and hence bandwidth independent, the impulsive stimulated Raman scattering mechanism proposed as the primary source for S∗ generation is discarded. To support this conclusion, previously published multi-pulse pump-dump-probe signals [17] are revisited to discard secondary mechanisms for S∗ formation.

Investigations into Alternative Desorption Agents for Amidoxime-Based Polymeric Uranium Adsorbents

Energy Technology Data Exchange (ETDEWEB)

Gill, Gary A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kuo, Li-Jung [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Strivens, Jonathan E. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wood, Jordana R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Wai, Chien [LCW Supercritical Technologies, Inc., Seattle, WA (United States); Pan, Horng-Bin [Univ. of Idaho, Moscow, ID (United States)

2015-06-01

Amidoxime-based polymeric braid adsorbents that can extract uranium (U) from seawater are being developed to provide a sustainable supply of fuel for nuclear reactors. A critical step in the development of the technology is to develop elution procedures to selectively remove U from the adsorbents and to do so in a manner that allows the adsorbent material to be reused. This study investigates use of high concentrations of bicarbonate along with targeted chelating agents as an alternative means to the mild acid elution procedures currently in use for selectively eluting uranium from amidoxime-based polymeric adsorbents.

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

Nano-Sized Cyclodextrin-Based Molecularly Imprinted Polymer Adsorbents for Perfluorinated Compounds—A Mini-Review

Directory of Open Access Journals (Sweden)

Abdalla H. Karoyo

2015-06-01

Full Text Available Recent efforts have been directed towards the design of efficient and contaminant selective remediation technology for the removal of perfluorinated compounds (PFCs from soils, sediments, and aquatic environments. While there is a general consensus on adsorption-based processes as the most suitable methodology for the removal of PFCs from aquatic environments, challenges exist regarding the optimal materials design of sorbents for selective uptake of PFCs. This article reviews the sorptive uptake of PFCs using cyclodextrin (CD-based polymer adsorbents with nano- to micron-sized structural attributes. The relationship between synthesis of adsorbent materials and their structure relate to the overall sorption properties. Hence, the adsorptive uptake properties of CD-based molecularly imprinted polymers (CD-MIPs are reviewed and compared with conventional MIPs. Further comparison is made with non-imprinted polymers (NIPs that are based on cross-linking of pre-polymer units such as chitosan with epichlorohydrin in the absence of a molecular template. In general, MIPs offer the advantage of selectivity, chemical tunability, high stability and mechanical strength, ease of regeneration, and overall lower cost compared to NIPs. In particular, CD-MIPs offer the added advantage of possessing multiple binding sites with unique physicochemical properties such as tunable surface properties and morphology that may vary considerably. This mini-review provides a rationale for the design of unique polymer adsorbent materials that employ an intrinsic porogen via incorporation of a macrocyclic compound in the polymer framework to afford adsorbent materials with tunable physicochemical properties and unique nanostructure properties.

Nano-Sized Cyclodextrin-Based Molecularly Imprinted Polymer Adsorbents for Perfluorinated Compounds—A Mini-Review

Science.gov (United States)

Karoyo, Abdalla H.; Wilson, Lee D.

2015-01-01

Recent efforts have been directed towards the design of efficient and contaminant selective remediation technology for the removal of perfluorinated compounds (PFCs) from soils, sediments, and aquatic environments. While there is a general consensus on adsorption-based processes as the most suitable methodology for the removal of PFCs from aquatic environments, challenges exist regarding the optimal materials design of sorbents for selective uptake of PFCs. This article reviews the sorptive uptake of PFCs using cyclodextrin (CD)-based polymer adsorbents with nano- to micron-sized structural attributes. The relationship between synthesis of adsorbent materials and their structure relate to the overall sorption properties. Hence, the adsorptive uptake properties of CD-based molecularly imprinted polymers (CD-MIPs) are reviewed and compared with conventional MIPs. Further comparison is made with non-imprinted polymers (NIPs) that are based on cross-linking of pre-polymer units such as chitosan with epichlorohydrin in the absence of a molecular template. In general, MIPs offer the advantage of selectivity, chemical tunability, high stability and mechanical strength, ease of regeneration, and overall lower cost compared to NIPs. In particular, CD-MIPs offer the added advantage of possessing multiple binding sites with unique physicochemical properties such as tunable surface properties and morphology that may vary considerably. This mini-review provides a rationale for the design of unique polymer adsorbent materials that employ an intrinsic porogen via incorporation of a macrocyclic compound in the polymer framework to afford adsorbent materials with tunable physicochemical properties and unique nanostructure properties. PMID:28347047

Enhanced vanillin production from ferulic acid using adsorbent resin.

Science.gov (United States)

Hua, Dongliang; Ma, Cuiqing; Song, Lifu; Lin, Shan; Zhang, Zhaobin; Deng, Zixin; Xu, Ping

2007-03-01

High vanillin productivity was achieved in the batch biotransformation of ferulic acid by Streptomyces sp. strain V-1. Due to the toxicity of vanillin and the product inhibition, fed-batch biotransformation with high concentration of ferulic acid was unsuccessful. To solve this problem and improve the vanillin yield, a biotransformation strategy using adsorbent resin was investigated. Several macroporous adsorbent resins were chosen to adsorb vanillin in situ during the bioconversion. Resin DM11 was found to be the best, which adsorbed the most vanillin and the least ferulic acid. When 8% resin DM11 (wet w/v) was added to the biotransformation system, 45 g l(-1) ferulic acid could be added continually and 19.2 g l(-1) vanillin was obtained within 55 h, which was the highest vanillin yield by bioconversion until now. This yield was remarkable for exceeding the crystallization concentration of vanillin and therefore had far-reaching consequence in its downstream processing.

Competitive adsorption of a two-component gas on a deformable adsorbent

International Nuclear Information System (INIS)

Usenko, A S

2014-01-01

We investigate the competitive adsorption of a two-component gas on the surface of an adsorbent whose adsorption properties vary due to the adsorbent deformation. The essential difference of adsorption isotherms for a deformable adsorbent both from the classical Langmuir adsorption isotherms of a two-component gas and from the adsorption isotherms of a one-component gas is obtained, taking into account variations in the adsorption properties of the adsorbent in adsorption. We establish bistability and tristability of the system caused by variations in adsorption properties of the adsorbent in competitive adsorption of gas particles on it. We derive conditions under which adsorption isotherms of a binary gas mixture have two stable asymptotes. It is shown that the specific features of the behavior of the system under study can be described in terms of a potential of the known explicit form. (paper)

Molecular and excited state properties of isomeric scarlet disperse dyes

Science.gov (United States)

Lim, Jihye; Szymczyk, Malgorzata; Mehraban, Nahid; Ding, Yi; Parrillo-Chapman, Lisa; El-Shafei, Ahmed; Freeman, Harold S.

2018-06-01

This work was part of an investigation aimed at characterizing the molecular and excited state properties of currently available disperse dyes developed to provide stability to extensive sunlight exposures when adsorbed on poly(ethylene terephthalate) (PET) fibers. Having completed the characterization of yellow, magenta, and cyan disperse dyes for PET-based fabrics used outdoors, our attention turned to the colors designed to enhance the color gamut of a standard 4-member (cyan/yellow/magenta/black) color set. The present study pertained specifically to the characterization of commercially available scarlet dyes. In this regard, HPLC analysis showed that a scarlet product used for PET coloration was mainly a 70/30 mixture of dyes, and the use of HRMS and single crystal X-ray diffraction analyses indicated that these two dyes were azo compounds derived from isomeric pyridine-based couplers which differed in the location of the primary amino (sbnd NH2) and anilino (sbnd NHPh) groups attached to the pyridine ring. One dye structure has the sbnd NHPh group para to the azo group (Sc2), while the other has that group in the ortho position (Sc3). The presence of either ortho substituent provides photostabilization through intramolecular H-bonding with the azo moiety. Further, results from molecular modeling studies showed that the lower excited state oxidation potential of Sc3 relative to that of Sc2 allows Sc3 to function as an energy quencher for the excited state of Sc2 - through thermodynamically favorable electron transfer.

Multicomponent Time-Dependent Density Functional Theory: Proton and Electron Excitation Energies.

Science.gov (United States)

Yang, Yang; Culpitt, Tanner; Hammes-Schiffer, Sharon

2018-04-05

The quantum mechanical treatment of both electrons and protons in the calculation of excited state properties is critical for describing nonadiabatic processes such as photoinduced proton-coupled electron transfer. Multicomponent density functional theory enables the consistent quantum mechanical treatment of more than one type of particle and has been implemented previously for studying ground state molecular properties within the nuclear-electronic orbital (NEO) framework, where all electrons and specified protons are treated quantum mechanically. To enable the study of excited state molecular properties, herein the linear response multicomponent time-dependent density functional theory (TDDFT) is derived and implemented within the NEO framework. Initial applications to FHF - and HCN illustrate that NEO-TDDFT provides accurate proton and electron excitation energies within a single calculation. As its computational cost is similar to that of conventional electronic TDDFT, the NEO-TDDFT approach is promising for diverse applications, particularly nonadiabatic proton transfer reactions, which may exhibit mixed electron-proton vibronic excitations.

Examination of uranium recovery technique from sea water using natural components for adsorbent

International Nuclear Information System (INIS)

Tanaka, Nobuyuki; Masaki, Hiroyuki; Shimizu, Takao; Tokiwai, Moriyasu

2010-01-01

In this study, we investigated the potency of natural components as adsorbent for uranium recovery from seawater. In addition, cost evaluation of uranium recovery from seawater using natural components for adsorbents was performed. Furthermore, new ideas on reservation system of adsorbents at sea area were proposed. Several poly-phenols were selected as adsorbent reagents, then they were adsorbed on the support such as cotton fiber by several methods as the followings; chemical syntheses, electrical beam irradiation, and traditional dyeing. As a result, the adsorbent made by traditional dyeing method using gallnut tannin as natural component, was showed high performance for uranium recovery from seawater on only the first. It was evaluated that traditional dyeing method had also advantage in the manufacturing cost, comparing with earlier method. Additionally, it was considered that reservation system of adsorbent at sea was able to be simplified compared with earlier system. Consequently, uranium recovery from sea water using natural components as adsorbent proposed in this study had a potency of practical use. (author)

International conference: Features of nuclear excitation states and mechanisms of nuclear reactions. 51. Meeting on nuclear spectroscopy and nuclear structure. The book of abstracts

International Nuclear Information System (INIS)

2001-01-01

Results of the LI Meeting on Nuclear Spectroscopy and Nuclear Structure are presented. Properties of excited states of atomic nuclei and mechanisms of nuclear reactions are considered. Studies on the theory of nucleus and fundamental interactions pertinent to experimental study of nuclei properties and mechanisms of nuclear reactions, technique and methods of experiment, application of nuclear-physical method, are provided [ru

Roles of the Excitation in Harvesting Energy from Vibrations.

Directory of Open Access Journals (Sweden)

Hui Zhang

Full Text Available The study investigated the role of excitation in energy harvesting applications. While the energy ultimately comes from the excitation, it was shown that the excitation may not always behave as a source. When the device characteristics do not perfectly match the excitation, the excitation alternately behaves as a source and a sink. The extent to which the excitation behaves as a sink determines the energy harvesting efficiency. Such contradictory roles were shown to be dictated by a generalized phase defined as the instantaneous phase angle between the velocity of the device and the excitation. An inductive prototype device with a diamagnetically levitated seismic mass was proposed to take advantage of the well established phase changing mechanism of vibro-impact to achieve a broader device bandwidth. Results suggest that the vibro-impact can generate an instantaneous, significant phase shift in response velocity that switches the role of the excitation. If introduced properly outside the resonance zone it could dramatically increase the energy harvesting efficiency.

New mechanism of spiral wave initiation in a reaction-diffusion-mechanics system.

Science.gov (United States)

Weise, Louis D; Panfilov, Alexander V

2011-01-01

Spiral wave initiation in the heart muscle is a mechanism for the onset of dangerous cardiac arrhythmias. A standard protocol for spiral wave initiation is the application of a stimulus in the refractory tail of a propagating excitation wave, a region that we call the "classical vulnerable zone." Previous studies of vulnerability to spiral wave initiation did not take the influence of deformation into account, which has been shown to have a substantial effect on the excitation process of cardiomyocytes via the mechano-electrical feedback phenomenon. In this work we study the effect of deformation on the vulnerability of excitable media in a discrete reaction-diffusion-mechanics (dRDM) model. The dRDM model combines FitzHugh-Nagumo type equations for cardiac excitation with a discrete mechanical description of a finite-elastic isotropic material (Seth material) to model cardiac excitation-contraction coupling and stretch activated depolarizing current. We show that deformation alters the "classical," and forms a new vulnerable zone at longer coupling intervals. This mechanically caused vulnerable zone results in a new mechanism of spiral wave initiation, where unidirectional conduction block and rotation directions of the consequently initiated spiral waves are opposite compared to the mechanism of spiral wave initiation due to the "classical vulnerable zone." We show that this new mechanism of spiral wave initiation can naturally occur in situations that involve wave fronts with curvature, and discuss its relation to supernormal excitability of cardiac tissue. The concept of mechanically induced vulnerability may lead to a better understanding about the onset of dangerous heart arrhythmias via mechano-electrical feedback.

Removal of lead (II) from metal plating effluents using sludge based activated carbon as adsorbent.

Science.gov (United States)

Raju, P; Saseetharan, M K

2010-01-01

A novel adsorbent was prepared from waste sludge obtained from a sugar mill for removing heavy metals from industrial wastewater. The adsorption studies were carried out in batch and continuous modes for both sugar mill sludge based carbon and commercial carbon. In batch studies, experiments were conducted at ambient temperature to assess the influence of the parameters such as pH, adsorbent dose, contact time and equilibrium concentration. Adsorption data for the prepared carbon was found to satisfy both the Freundlich and Langmuir isotherms. Column studies were carried out to delineate the effect of varying depth of carbon at constant flow rate. The breakthrough curves were drawn to establish the mechanism. The result shows that the sludge based activated carbon can be used as an alternative for commercial carbon.

Concurrent removal of elemental mercury and SO2 from flue gas using a thiol-impregnated CaCO3-based adsorbent: a full factorial design study.

Science.gov (United States)

Balasundaram, Karthik; Sharma, Mukesh

2018-03-22

Mercury (Hg) emitted from coal-based thermal power plants (CTPPs) can accumulate and bio-magnify in the food chain, thereby posing a risk to humans and wildlife. The central idea of this study was to develop an adsorbent which can concurrently remove elemental mercury (Hg 0 ) and SO 2 emitted from coal-based thermal power plants (CTPPs) in a single unit operation. Specifically, a composite adsorbent of CaCO 3 impregnated with 2-mercaptobenimidazole (2-MBI) (referred to as modified calcium carbonate (MCC)) was developed. While 2-MBI having sulfur functional group could selectively adsorb Hg 0 , CaCO 3 could remove SO 2 . Performance of the adsorbent was evaluated in terms of (i) removal (%) of Hg 0 and SO 2 , (ii) adsorption mechanism, (iii) adsorption kinetics, and (iv) leaching potential of mercury from spent adsorbent. The adsorption studies were performed using a 2 2 full factorial design of experiments with 15 ppbV of Hg 0 and 600 ppmV of SO 2 . Two factors, (i) reaction temperature (80 and 120 °C; temperature range in flue gas) and (ii) mass of 2-MBI (10 and 15 wt%), were investigated for the removal of Hg 0 and SO 2 (as %). The maximum Hg 0 and SO 2 removal was 86 and 93%, respectively. The results of XPS characterization showed that chemisorption is the predominant mechanism of Hg 0 and SO 2 adsorption on MCC. The Hg 0 adsorption on MCC followed Elovich kinetic model which is also indicative of chemisorption on heterogeneous surface. The toxicity characteristic leaching procedure (TCLP) and synthetic precipitation leaching procedure (SPLP) leached mercury from the spent adsorbent were within the acceptable levels defined in these tests. The engineering significance of this study is that the 2-MBI-modified CaCO 3 -based adsorbent has potential for concurrent removal of Hg 0 and SO 2 in a single unit operation. With only minor process modifications, the newly developed adsorbent can replace CaCO 3 in the flue-gas desulfurization (FGD) system.

Excited, bound and resonant positron-atom systems

International Nuclear Information System (INIS)

Bromley, M W J; Mitroy, J

2010-01-01

Calculations have demonstrated that eleven neutral atoms can bind positrons, while many more can bind positronium. This is a short review of recent progress made in understanding some of the underlying mechanisms. The emphasis here being on configuration interaction calculations with excited state configurations. These have demonstrated the existence of a 2 P o excited state of e + Ca, which consists predominantly of a positronium cluster orbiting the Ca + ion in the L = 1 partial wave. Preliminary results are presented of excited state positron binding to a model alkali atom, where the excited 1 P o states are stable over a limited region. Implications for the unnatural parity, 2,4 S o , states of PsH, LiPs, NaPs and KPs are also discussed. The e + Mg, e + Cu, e + Zn and e + Cd systems show a lack of a 2 P o excited state, each instead possessing a low-energy p-wave shape resonance of varying strength.

PERVAPORATION USING ADSORBENT-FILLED MEMBRANES

Science.gov (United States)

Membranes containing selective fillers, such as zeolites and activated carbon, can improve the separation by pervaporation. Applications of adsorbent-filled membranes in pervaporation have been demonstrated by a number of studies. These applications include removal of organic co...

Elastic wave excitation in centrosymmetric strontium titanate crystals

International Nuclear Information System (INIS)

Yushin, N.K.; Sotnikov, A.V.

1980-01-01

The main experimental dependencies are measured and the excitation mechanism of elastic waves in centrosymmetric crystals is established. The surface generation of three-dimensional elastic waves of the 30 MHz frequency in strontium titanate crystals is observed and studied. Elastic wave excitation is observed in the 4 350 K temperature range. The efficiency of hysteresis excitation depends on the external electric field. The effect of light irradiation on the amplitude of excited elastic waves is observed. It is shown that escitation is connected with linearization of electrostriction by the constant electric field appearing in a near-surface crystal layer due to phenomena in the Schottky barrier and appearance of electretic near-electrode layers

Valorization of solid waste products from olive oil industry as potential adsorbents for water pollution control--a review.

Science.gov (United States)

Bhatnagar, Amit; Kaczala, Fabio; Hogland, William; Marques, Marcia; Paraskeva, Christakis A; Papadakis, Vagelis G; Sillanpää, Mika

2014-01-01

The global olive oil production for 2010 is estimated to be 2,881,500 metric tons. The European Union countries produce 78.5% of the total olive oil, which stands for an average production of 2,136,000 tons. The worldwide consumption of olive oil increased of 78% between 1990 and 2010. The increase in olive oil production implies a proportional increase in olive mill wastes. As a consequence of such increasing trend, olive mills are facing severe environmental problems due to lack of feasible and/or cost-effective solutions to olive-mill waste management. Therefore, immediate attention is required to find a proper way of management to deal with olive mill waste materials in order to minimize environmental pollution and associated health risks. One of the interesting uses of solid wastes generated from olive mills is to convert them as inexpensive adsorbents for water pollution control. In this review paper, an extensive list of adsorbents (prepared by utilizing different types of olive mill solid waste materials) from vast literature has been compiled, and their adsorption capacities for various aquatic pollutants removal are presented. Different physicochemical methods that have been used to convert olive mill solid wastes into efficient adsorbents have also been discussed. Characterization of olive-based adsorbents and adsorption mechanisms of various aquatic pollutants on these developed olive-based adsorbents have also been discussed in detail. Conclusions have been drawn from the literature reviewed, and suggestions for future research are proposed.

Chapter 6 Quantum Mechanical Methods for Loss-Excitation and Loss-Ionization in Fast Ion-Atom Collisions

Science.gov (United States)

Belkic, Dzevad

quantum mechanical perturbation theories applied to electron loss collisions involving two hydrogen-like atoms. Both the one- and two-electron transitions (target unaffected by collision, as well as loss-ionization) are thoroughly examined in various intervals of impact energies varying from the threshold via the Massey peak to the Bethe asymptotic region. Systematics are established for the fast, simple, and accurate computations of cross sections for loss-excitation and loss-ionization accounting for the entire spectra of all four particles, including two free electrons and two free protons. The expounded algorithmic strategy of quantum mechanical methodologies is of great importance for wide applications to particle transport physics, especially in fusion research and hadron radiotherapy. This should advantageously replace the current overwhelming tendency in these fields for using phenomenological modeling with artificial functions extracted from fitting the existing experimental/theoretical data bases for cross sections.

Relaxation of helium levels excited by heavy ion impact: III.- Orientation by anisotropic relaxation of excited atoms in previously aligned states

International Nuclear Information System (INIS)

Chamoun, E.; Lombardi, M.; Carre, M.; Gaillard, M.L.

1977-01-01

In the last paper of this series devoted to relaxation phenomena in a low pressure cell of helium excited by an accelerated ion beam, experimental evidence is given for a new mechanism of transfer between alignment and orientation through anisotropic relaxation of initially aligned excited states. The theory predicting this effect is briefly outlined and then description is given of the exact experimental conditions to detect the circularly polarized component of the light emitted by the target excited in the 4 1 D level of He I by Na + impact [fr

Comparative evaluation of selected starches as adsorbent for Thin ...

African Journals Online (AJOL)

The most commonly used is silica gel which is an inorganic adsorbent. Organic substances like cellulose, polyethylene are also used. All these are imported into Nigeria and are unhealthy for economic policies. Most commonly used adsorbent may not be easy to produce locally, but starch, which is a very common product, ...

Application of low-cost adsorbents for dye removal--a review.

Science.gov (United States)

Gupta, V K; Suhas

2009-06-01

Dyes are an important class of pollutants, and can even be identified by the human eye. Disposal of dyes in precious water resources must be avoided, however, and for that various treatment technologies are in use. Among various methods adsorption occupies a prominent place in dye removal. The growing demand for efficient and low-cost treatment methods and the importance of adsorption has given rise to low-cost alternative adsorbents (LCAs). This review highlights and provides an overview of these LCAs comprising natural, industrial as well as synthetic materials/wastes and their application for dyes removal. In addition, various other methods used for dye removal from water and wastewater are also complied in brief. From a comprehensive literature review, it was found that some LCAs, in addition to having wide availability, have fast kinetics and appreciable adsorption capacities too. Advantages and disadvantages of adsorbents, favourable conditions for particular adsorbate-adsorbent systems, and adsorption capacities of various low-cost adsorbents and commercial activated carbons as available in the literature are presented. Conclusions have been drawn from the literature reviewed, and suggestions for future research are proposed.

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.

Preparation and characterization of a novel adsorbent from Moringa oleifera leaf

Science.gov (United States)

Bello, Olugbenga Solomon; Adegoke, Kayode Adesina; Akinyunni, Opeyemi Omowumi

2017-06-01

A new and novel adsorbent was obtained by impregnation of Moringa oleifera leaf in H2SO4 and NaOH, respectively. Prepared adsorbents were characterized using elemental analysis, FT-IR, SEM, TGA and EDX analyses, respectively. The effects of operational parameters, such as pH, moisture content, ash content, porosity and iodine number on these adsorbents were investigated and compared with those of commercial activated carbon (CAC). EDX results of acid activated M. oleifera leaf have the highest percentage of carbon by weight (69.40 %) and (76.11 %) by atom, respectively. Proximate analysis showed that the fixed carbon content of acid activated M. oleifera leaf (69.14 ± 0.01) was the highest of all adsorbents studied. Conclusively, the present investigation shows that acid activated M. oleifera leaf is a good alternative adsorbent that could be used in lieu of CAC for recovery of dyes and heavy metal from aqueous solutions and other separation techniques.

An innovative zinc oxide-coated zeolite adsorbent for removal of humic acid

Science.gov (United States)

Zinc oxide (ZnO)-coated zeolite adsorbents were developed by both nitric acid modification and Zn(NO3)2•6H2O functionalization of zeolite. The developed adsorbents were used for the removal of humic acid (HA) from aqueous solutions. The adsorption capacity of the adsorbents at 21...

Anisotropy of electronic states excited in ion-atom collisions

International Nuclear Information System (INIS)

Boskamp, E.B.

1983-01-01

The author reports coincidence measurements made on the He + + Ne and He + + He systems. The complex population amplitudes for the magnetic sublevels of the investigated excited states, Ne(2p 4 3s 2 ) 1 D and He(2p 2 ) 1 D, were completely determined and possible excitation mechanisms are described. (Auth.)

Electronic properties of adsorbates and clean surfaces of metals and semiconductors

International Nuclear Information System (INIS)

Lecante, J.

1980-01-01

This paper surveys recent progress in experimental studies on electronic properties of adsorbates and clean metal surfaces. Electron spectroscopy and particularly angle resolved photoelectron spectroscopy appears to be a very powerful tool to get informations on electronic levels of adsorbates or clean surfaces. Moreover this technique may also give informations about the atomic geometry of the surface. Experimental investigation about surface plasmons, surface states, core level shifts are presented for clean surfaces. As examples of adsorbate covered surfaces two typical cases are chosen: two dimensional band structure and oriented molecules. Finally the photoelectron diffraction may be used for surface structure determination either in the case of an adsorbate or a clean metal surface [fr

Excitation model of pacemaker cardiomyocytes of cardiac conduction system

Science.gov (United States)

Grigoriev, M.; Babich, L.

2015-11-01

Myocardium includes typical and atypical cardiomyocytes - pacemakers, which form the cardiac conduction system. Excitation from the atrioventricular node in normal conditions is possible only in one direction. Retrograde direction of pulses is impossible. The most important prerequisite for the work of cardiomyocytes is the anatomical integrity of the conduction system. Changes in contractile force of the cardiomyocytes, which appear periodically, are due to two mechanisms of self-regulation - heterometric and homeometric. Graphic course of the excitation pulse propagation along the heart muscle more accurately reveals the understanding of the arrhythmia mechanism. These models have the ability to visualize the essence of excitation dynamics. However, they do not have the proper forecasting function for result estimation. Integrative mathematical model enables further investigation of general laws of the myocardium active behavior, allows for determination of the violation mechanism of electrical and contractile function of cardiomyocytes. Currently, there is no full understanding of the topography of pacemakers and ionic mechanisms. There is a need for the development of direction of mathematical modeling and comparative studies of the electrophysiological arrangement of cells of atrioventricular connection and ventricular conduction system.

New mechanism of spiral wave initiation in a reaction-diffusion-mechanics system.

Directory of Open Access Journals (Sweden)

Louis D Weise

Full Text Available Spiral wave initiation in the heart muscle is a mechanism for the onset of dangerous cardiac arrhythmias. A standard protocol for spiral wave initiation is the application of a stimulus in the refractory tail of a propagating excitation wave, a region that we call the "classical vulnerable zone." Previous studies of vulnerability to spiral wave initiation did not take the influence of deformation into account, which has been shown to have a substantial effect on the excitation process of cardiomyocytes via the mechano-electrical feedback phenomenon. In this work we study the effect of deformation on the vulnerability of excitable media in a discrete reaction-diffusion-mechanics (dRDM model. The dRDM model combines FitzHugh-Nagumo type equations for cardiac excitation with a discrete mechanical description of a finite-elastic isotropic material (Seth material to model cardiac excitation-contraction coupling and stretch activated depolarizing current. We show that deformation alters the "classical," and forms a new vulnerable zone at longer coupling intervals. This mechanically caused vulnerable zone results in a new mechanism of spiral wave initiation, where unidirectional conduction block and rotation directions of the consequently initiated spiral waves are opposite compared to the mechanism of spiral wave initiation due to the "classical vulnerable zone." We show that this new mechanism of spiral wave initiation can naturally occur in situations that involve wave fronts with curvature, and discuss its relation to supernormal excitability of cardiac tissue. The concept of mechanically induced vulnerability may lead to a better understanding about the onset of dangerous heart arrhythmias via mechano-electrical feedback.

Biological adsorbent for water decontamination from uranium

Energy Technology Data Exchange (ETDEWEB)

Jilek, R [Vyzkumny Ustav Veterinarniho Lekarstvi, Brno-Medlanky (Czechoslovakia); Fuska, J; Nemec, P [Slovenska Vysoka Skola Technicka, Bratislava (Czechoslovakia). Chemickotechnologicka Fakulta

1978-01-01

A study was made into the capacity of native and heat-denaturated mycelium to adsorb uranium salts from solutions and into the effect of uranium on the growth of the microorganism biomass. The presence of uranium did not inhibit the growth of Penicillium and Aspergillus strains used at a concentration of up to 5x10/sup -4/ M/dm/sup 3/. Uranium added to a nutrient medium produced complexes with phosphorus ions which were adsorbed on the surface of growing hyphae, thus the removal of the mycelium also removed uranium. The results of the experiments with denaturated mycelium of the same strains suggested that uranium was also bound to the biomass with chemical bonds so that mycelium acted as a ''multifunction ion exchanger'' from which adsorbed uranium can be removed step by step by elution. A sorbent of a three-dimensional structure could be prepared from a dried native mycelium using reinforcing resins, which prevented leakage of the biomass. Uranium sorption by biosorbents is a function of the concentration of the cation sorbed and of the pH of the solution.

Biological adsorbent for water decontamination from uranium

International Nuclear Information System (INIS)

Jilek, R.; Fuska, J.; Nemec, P.

1978-01-01

A study was made into the capacity of native and heat-denaturated mycelium to adsorb uranium salts from solutions and into the effect of uranium on the growth of the microorganism biomass. The presence of uranium did not inhibit the growth of Penicillium and Aspergillus strains used at a concentration of up to 5x10 -4 M/dm 3 . Uranium added to a nutrient medium produced complexes with phosphorus ions which were adsorbed on the surface of growing hyphae, thus the removal of the mycelium also removed uranium. The results of the experiments with denaturated mycelium of the same strains suggested that uranium was also bound to the biomass with chemical bonds so that mycelium acted as a ''multifunction ion exchanger'' from which adsorbed uranium can be removed step by step by elution. A sorbent of a three-dimensional structure could be prepared from a dried native mycelium using reinforcing resins, which prevented leakage of the biomass. Uranium sorption by biosorbents is a function of the concentration of the cation sorbed and of the pH of the solution. (author)

Characterisation of lignite as an industrial adsorbent

Energy Technology Data Exchange (ETDEWEB)

Ying Qi; Andrew F.A. Hoadley; Alan L. Chaffee; Gil Garnier [Monash University, Clayton, Vic. (Australia). Department of Chemical Engineering

2011-04-15

An alternative use of the abundant and inexpensive lignite (also known as brown coal) as an industrial adsorbent has been characterised. The adsorptive properties of two Victorian lignite without any pre-treatment were investigated using the cationic methylene blue dye as a model compound in aqueous solutions. Two commercial activated carbon products were also studied for comparison. The adsorption equilibrium of the four adsorbents was better described by the Langmuir isotherm model than the Freundlich model. The adsorption capacities of the two untreated lignite adsorbents, Loy Yang and Yallourn, calculated using Langmuir isotherms were 286 and 370 mg/g, respectively, higher than a coconut shell-based activated carbon (167 mg/g), but lower than a coal-based activated carbon (435 mg/g). Surface area results suggested that larger micropores and mesopores were important for achieving good methylene blue adsorption by the activated carbons. However, FTIR and cation exchange capacity analyses revealed that, for the lignite, chemical interactions between lignite surface functional groups and methylene blue molecules occurred, thereby augmenting its adsorption capacity. 63 refs., 3 figs., 7 tabs.

Converting untreated waste office paper and chitosan into aerogel adsorbent for the removal of heavy metal ions.

Science.gov (United States)

Li, Zhanying; Shao, Lin; Ruan, Zehai; Hu, Wenbin; Lu, Lingbin; Chen, Yongjun

2018-08-01

The utilization of waste paper, an obsolete recyclable resource, helps to save resources and protect environment. In this paper, an aerogel was prepared to convert the waste paper into a useful material, which was used to adsorb heavy metal ions and handle water pollution. Combining waste office paper and chitosan, the aerogel obtained the enhanced mechanical strength, acid resistance and high adsorption capacity (up to 156.3 mg/g for Cu 2+ ). This adsorption process obeyed the pseudo-second order model and the Langmuir model. The research showed that a coordination compound was formed between amino group and Cu 2+ during the adsorption process. The adsorbent could be regenerated well in 0.1 M H 2 SO 4 with up to 98.3% desorption efficiency. The low cost, environmental friendliness, excellent adsorption capacity and regeneration ability made this novel aerogel a promising adsorbent for heavy metal ions. And this conversion is an effective reuse way of waste paper too. Copyright © 2018 Elsevier Ltd. All rights reserved.

Electron-Impact Excitation of Uracil Luminescence on a Ceramic Surface

Science.gov (United States)

Shafranyosh, I. I.; Mitropolskiy, I. E.; Kuzma, V. V.; Svyda, Yu. Yu.; Sukhoviya, M. I.

2018-03-01

Photoelectron spectroscopy was applied to pyrimidine nitrogenous bases, an important class of six-membered heterocyclic compounds incorporated into nucleic acids. The emission spectrum of uracil adsorbed on a ceramic surface that was obtained by bombardment with 600-eV electrons in a high vacuum was analyzed. Broad bands with maxima at 335, 435, and 495 nm were observed in the UV and visible regions. The strongest band (λ = 335 nm) was attributed to fluorescence and corresponded to a singlet-singlet transition from the first excited electronic state into the molecular ground state. Electronic transitions from a triplet T1 into the ground state formed a weaker phosphorescence band (λ = 435 nm). The nature of the band maximum at 495 nm is discussed. The obtained luminescence spectrum was compared with photoluminescence spectra in various phases.

Power system stabilization by superconducting magnetic energystorage connected to rotating exciter

OpenAIRE

Mitani, Yasunori; Tsuji, K

1993-01-01

The authors describe a combination of a rotating exciter and a superconducting magnetic energy storage (SMES) system for efficient power system stabilization. A SMES system connected to an exciter rotating with a turbine-rotor shaft is proposed. The exciter is installed exclusively to supply current for the SMES. Since electrical power output from the SMES is converted into a mechanical torque of the generator directly by the exciter, it is expected that power swings of the generator will be ...

The dynamics of highly excited hydrogen atoms in microwave fields: Application of the Floquet picture of quantum mechanics

International Nuclear Information System (INIS)

Holthaus, M.

1990-04-01

The study of short-time phenomena in strongly interacting quantum systems requires on the theoretical side the development of methods, which are both non-perturbative and 'dynamical', which thus regard the change of outer parameters in the slope of time. For systems with a periodic, fast and a further slow, parametric time dependence both requirements are fulfilled by the Floquet picture of quantum mechanics. This picture, which starts from the adiabatic evolution on effective quasi-energy surfaces, is presented in the first chapter of the present thesis, whereby especially the term of the adiabaticity for periodically time dependent systems is explained. In the second chapter the Floquet theory is applied to the description of microwave experiments with highly excited hydrogen atoms. Here it is shown that the Floquet picture permits to understand a manifold of experimental observations under a unified point of view. Really these microwave experiments offer an ideal possibility for the test of the Floquet picture: On the one hand there is the strength of the outer field of the same order of magnitude as that of the nuclear field, by which the highly excited electron is bound, on the other hand in the experiment an extremely precise control of amplitude, frequency, and pulse shape is possible, so that the conditions for a detailed comparison of theory and experiment are given. The insights, which model calculations yield in the dynamics of highly excited hydrogen atoms in strong alternating fields, allow a prediction of further effects, for which it is to be looked for in new experiments. In the following third chapter some further aspects of these model calculations are discussed, whereby also common properties of the dynamics of excited atoms in microwave fields and that of atoms under the influence of strong laser pulses are discussed. (orig./HSI) [de

Development of Silver-exchanged Adsorbents for the Removal of Fission Iodine from Alkaline Dissolution

International Nuclear Information System (INIS)

Kim, Taewoon; Lee, Seung-Kon; Lee, Suseung; Lee, Jun Sig

2015-01-01

Most of the iodine exists in the caustic dissolution as iodide form. KAERI is developing LEU-based fission 99 Mo production process which is connected to the new research reactor, which is being constructed in Kijang, Busan, Korea. In KAERI process, silver-exchanged adsorbent is used to adsorb iodide from the solution. Adsorbed iodide can be recovered and recycled for radiopharmaceuticals. In KAERI process, silver-exchanged adsorbent is used to adsorb iodide from the solution. Adsorbed iodide can be recovered and recycled for radiopharmaceuticals. Synthesis of silver-doped alumina is conducted in two ways. One is using the ascorbic acid as a reducing agent. However, this method is impossible to control

Analysis of Adsorbate-Adsorbate and Adsorbate-Adsorbent Interactions to Decode Isosteric Heats of Gas Adsorption.

Science.gov (United States)

Madani, S Hadi; Sedghi, Saeid; Biggs, Mark J; Pendleton, Phillip

2015-12-21

A qualitative interpretation is proposed to interpret isosteric heats of adsorption by considering contributions from three general classes of interaction energy: fluid-fluid heat, fluid-solid heat, and fluid-high-energy site (HES) heat. Multiple temperature adsorption isotherms are defined for nitrogen, T=(75, 77, 79) K, argon at T=(85, 87, 89) K, and for water and methanol at T=(278, 288, 298) K on a well-characterized polymer-based, activated carbon. Nitrogen and argon are subjected to isosteric heat analyses; their zero filling isosteric heats of adsorption are consistent with slit-pore, adsorption energy enhancement modelling. Water adsorbs entirely via specific interactions, offering decreasing isosteric heat at low pore filling followed by a constant heat slightly in excess of water condensation enthalpy, demonstrating the effects of micropores. Methanol offers both specific adsorption via the alcohol group and non-specific interactions via its methyl group; the isosteric heat increases at low pore filling, indicating the predominance of non-specific interactions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Effect of γ-ray irradiation on adsorbents used in organic waste treatment

International Nuclear Information System (INIS)

Unsworth, T.J.; Krishma, R.; Pimblott, S.M.

2015-01-01

Radioactive organic liquids (ROLs) are waste that require specific treatment. The Arvia process, developed by Arvia Technology Ltd., combines adsorption of organic material with electrochemical oxidation. This work focuses on the effect of γ-rays on the performance of adsorbents used in the Arvia process. Adsorbents used in this experimental study were provided by Arvia Technology Ltd. Specifically, Nyex 1000, a flake like carbon-based adsorbent, and Nyex 2105, a carbon-based adsorbent with a granular morphology. The γ-ray irradiation experiments were carried out using a Co-60 irradiator. The impact of irradiation on the microstructure, the adsorption capacity and the leaching of the 2 adsorbents were studied. The results show that no significant changes were detected in terms of structure, adsorption capacity and leaching of ions. The results of this paper are promising for the use of Nyex 1000 and Nyex 2105 as adsorbents in electrochemical waste treatment processes which involve high levels of γ-rays. The article is followed by the slides of the presentation

The Dynamics and Structures of Adsorbed Surfaces

DEFF Research Database (Denmark)

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

1978-01-01

. Elastic neutron diffraction measurements, determining the two-dimensional structural ordering of the adsorbed films, have been performed on layers of N2, Ar, H2, D2, O2, Kr, and He. Measurements on layers of larger molecules such as CD4 and ND3 have also been reported. Inelastic neutron scattering...... measurements, studying the dynamics of the adsorbed films are only possible in a few especially favourable cases such as 36Ar and D2 films, where the coherent phonon scattering cross-sections are very large. In other cases incoherent scattering from hydrogen can give information about e.g. the mobility...

First-principles study of SF_6 decomposed gas adsorbed on Au-decorated graphene

International Nuclear Information System (INIS)

Zhang, Xiaoxing; Yu, Lei; Gui, Yingang; Hu, Weihua

2016-01-01

Graphical abstract: - Highlights: • We theoretically investigated the decomposed gaseous components of sulfur hexafluoride (SF_6), namely, H_2S, SO_2, SOF_2, and SO_2F_2, adsorbed on pristine and Au-embedded graphene based on DFT-D, in which the van der Waals effect is considered. • H_2S, SO_2, SOF_2, and SO_2F_2 are chemisorption on Au-doped graphene, appreciably stronger than physisorption on pristine graphene in which the van der Waals dominates. • Only H_2S exhibits n-type doping to Au-graphene, whereas the rest gases exhibit p-type doping. The n-type and p-type sensing behaviors that Au-doped graphene displays to different gases play a crucial role in selective sensing application. • Magnetic moments fluctuate substantially in the original Au-graphene when H_2S and SO_2 are adsorbed. While the adsorption effects of SOF_2 and SO_2F_2 generate magnetism quenching. The different changes of magnetic moments in every adsorption system provide another approach to selective detection. • The charge transfer mechanism is deeply discussed in this paper. - Abstract: We theoretically investigated the decomposed gaseous components of sulfur hexafluoride (SF_6), namely, H_2S, SO_2, SOF_2, and SO_2F_2, 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. SOF_2 and SO_2F_2 exhibit a strong chemisorption interaction with Au-graphene, while H_2S and SO_2 exhibit quasi-molecular binding

Excitation mechanisms in 1 mJ picosecond laser induced low pressure He plasma and the resulting spectral quality enhancement

Energy Technology Data Exchange (ETDEWEB)

Idris, Nasrullah; Lahna, Kurnia; Abdulmadjid, Syahrun Nur [Department of Physics, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Ramli, Muliadi [Department of Chemistry, Faculty of Mathematics and Natural Sciences, Syiah Kuala University, Darussalam, Banda Aceh 23111, NAD (Indonesia); Suyanto, Hery [Department of Physics, Faculty of Mathematics and Natural Sciences, Udayana University, Kampus Bukit Jimbaran, Denpasar 80361, Bali (Indonesia); Marpaung, Alion Mangasi [Department of Physics, Faculty of Mathematics and Natural Sciences, Jakarta State University, 10 Rawamangun, Jakarta (Indonesia); Pardede, Marincan [Department of Electrical Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Jobiliong, Eric [Department of Industrial Engineering, University of Pelita Harapan, 1100 M.H. Thamrin Boulevard, Lippo Village, Tangerang 15811 (Indonesia); Hedwig, Rinda; Lie, Zener Sukra [Department of Computer Engineering, Bina Nusantara University, 9 K.H. Syahdan, Jakarta 14810 (Indonesia); Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Jakarta 11630 (Indonesia); Suliyanti, Maria Margaretha [Research Center for Physics, Indonesia Institute of Sciences, Kawasan PUSPIPTEK, Serpong, Tangerang Selatan 15314, Banten (Indonesia); Lie, Tjung Jie; Kurniawan, Koo Hendrik, E-mail: kurnia18@cbn.net.id [Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Jakarta 11630 (Indonesia); Kagawa, Kiichiro [Fukui Science Education Academy, Takagi Chuou 2 choume, Fukui 910-0804 (Japan); Tjia, May On [Research Center of Maju Makmur Mandiri Foundation, 40/80 Srengseng Raya, Jakarta 11630 (Indonesia); Physics of Magnetism and Photonics Group, Faculty of Mathematics and Natural Sciences, Bandung Institute of Technology, 10 Ganesha, Bandung 40132 (Indonesia)

2015-06-14

We report in this paper the results of an experimental study on the spectral and dynamical characteristics of plasma emission induced by 1 mJ picoseconds (ps) Nd-YAG laser using spatially resolved imaging and time resolved measurement of the emission intensities of copper sample. This study has provided the experimental evidence concerning the dynamical characteristics of the excitation mechanisms in various stages of the plasma formation, which largely consolidate the basic scenarios of excitation processes commonly accepted so far. However, it is also clearly shown that the duration of the shock wave excitation process induced by ps laser pulses is much shorter than those observed in laser induced breakdown spectroscopy employing nanosecond laser at higher output energy. This allows the detection of atomic emission due exclusively to He assisted excitation in low pressure He plasma by proper gating of the detection time. Furthermore, the triplet excited state associated with He I 587.6 nm is shown to be the one most likely involved in the process responsible for the excellent spectral quality as evidenced by its application to spectrochemical analysis of a number of samples. The use of very low energy laser pulses also leads to minimal destructive effect marked by the resulted craters of merely about 10 μm diameter and only 10 nm deep. It is especially noteworthy that the excellent emission spectrum of deuterium detected from D-doped titanium sample is free of spectral interference from the undesirable ubiquitous water molecules without a precleaning procedure as applied previously and yielding an impressive detection limit of less than 10 μg/g. Finally, the result of this study also shows a promising application to depth profiling of impurity distribution in the sample investigated.

Adsorbents for radioactive organic solvent wastes

International Nuclear Information System (INIS)

Ichinose, Shigeo; Kiribayashi, Takehiko.

1986-01-01

Purpose: To enable to settle radioactive solvents such as tributyl phosphate (TBP) and n-dodecane as they are without using hydrophobicizing agent such as quaternary ammonium salts. Constitution: The adsorbents are prepared by replacing interlaminer ions of swelling-type synthetic mica with alkaline earth metals or metal ions. For instance, synthetic micas introduced with Zr 4+ or Ca 2+ between the layers provide quite different functions from those of starting materials due to the properties of ions introduced between the layers. That is, they provide an intense affinity to organic phosphates such as TBP and transform into material showing a property of adsorbing and absorbing them. Particularly, the fixing nature to the phosphor content constituting TBP is significantly increased. (Horiuchi, T.)

The formation and decay of triply excited He- states in e-He scattering

International Nuclear Information System (INIS)

Heideman, H.G.M.

1988-01-01

A description is given of doubly and triply excited negative-ion states and their effects on the electron impact excitation of atomic states. Mechanisms for indirect excitation of singly excited states are discussed with respect to:- negative-ion resonance, autoionisation and post-collision interaction, and excitation of an autoionising state via a negative ion resonance. A classification of doubly excited states is considered. Experimental results on the excitation of the n'S states of helium as a function of the incident electron energy are presented, along with theoretical PCI (post collision interaction) profiles in excitation functions, and an interpretation of the results. (UK)

Selective recovery of Ag(I) coordination anion from simulate nickel electrolyte using corn stalk based adsorbent modified by ammonia–thiosemicarbazide

Energy Technology Data Exchange (ETDEWEB)

Xiong, Ying, E-mail: xiongying_1977@hotmail.com; Wan, Li; Xuan, Jing; Wang, Yongwei; Xing, Zhiqing; Shan, Weijun; Lou, Zhenning

2016-01-15

Highlights: • We developed a “green” corn stalk adsorbent treated by thiosemicarbazide–glutaraldehyde. • Adsorption mechanism of AgCl{sub i}{sup 1−i} could be electrostatic interaction with C−SH{sup +}−N and C=SH{sup +} group. • The gel could selectively adsorb AgCl{sub i}{sup 1−i} coordination anion from the Ag(I)–Cu(II)–Ni(II) simulate nickel electrolyte. - Abstract: In nickel electrolyte, Ag(I) was present at trace level concentration (10–20 mg L{sup −1}) and existed in the form of AgCl{sub i}{sup 1−i} coordination anion, instead of Ag{sup +} positive ion usually in several sources. In the present study, TSC-NH{sub 3}-OCS adsorbent based on natural corn stalk modified by ammonia (NH{sub 3})–thiosemicarbazide (TSC) was synthesized and characterized using some instrumental techniques. The TSC-NH{sub 3}-OCS adsorbent could selectively adsorb Ag(I) as AgCl{sub i}{sup 1−i} coordination anion from the Ag(I)–Cu(II)–Ni(II) simulate nickel electrolyte, especially in the case of the very high levels of Cu(II) and Ni(II), which significantly outperforms the commercial available resins. The adsorption mechanism was believed to be electrostatic interaction of the protonated bands of AgCl{sub 4}{sup 3−} with protonated thiol form of the thioamide units by FTIR and XPS analysis. The maximum adsorption capacity in the Ag(I) single and Ag(I)–Cu(II)–Ni(II) ternary system were obtained and calculated as 153.54 and 46.69 mg g{sup −1}, respectively. The reasons that the maximum adsorption capacity of AgCl{sub i}{sup 1−i} from the single and ternary system varied widely could be explained by adsorption kinetic and thermodynamic results. In addition, three successive sorption/desorption cycle runs from ternary system were performed which indicated that the TSC-NH{sub 3}-OCS adsorbent has a good performance for recovery Ag(I) from simulate nickel electrolyte.

Synthesis of adsorbent from Tamarix hispida and modified by lanthanum metal for fluoride ions removal from wastewater: Adsorbent characteristics and real wastewater treatment data

Directory of Open Access Journals (Sweden)

Nasim Habibi

2017-08-01

Full Text Available This data article describes a facile method for production of an adsorbent from Tamarix hispida wasted wood and modified by lanthanum metal for fluoride ions removal from wastewater. The main characteristics of the adsorbent consist of BET surface area, functional groups, and elemental analysis is presented. The data for attenuating the pollutants from a real wastewater treatment which was provided from a glass factory is also represented. More than 90% of fluoride content of the real wastewater was treated by the adsorbent. Generally, these data would be informative for extend research aim to industrial wastewater treatment and those who work in the wastewater treatment plants.

Scanning tunneling spectroscopy of Co adsorbates on superconducting Pb nanostructures

Energy Technology Data Exchange (ETDEWEB)

Decker, Regis; Caminale, Michael; Oka, Hirofumi; Stepniak, Agnieszka; Leon Vanegas, Augusto A.; Sander, Dirk; Kirschner, Juergen [Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, 06120 Halle (Germany)

2015-07-01

Superconductivity in low-dimensional structures has become an active research area. In order to understand the superconducting pairing, long-standing work has been devoted to the pair breaking effect, where magnetic impurities break Cooper pair singlets. We performed scanning tunneling spectroscopy at low temperature on Co adsorbates on superconducting Pb nanoislands. On the Co adsorbates, we observe spectral features in the superconductor's energy gap, which we attribute to magnetic impurity induced bound states, a hallmark of the pair breaking effect. We discuss the response of the superconducting islands to the presence of Co adsorbates.

Picosecond transient absorption spectra of aminosalicylates in confirmation of the triple excitation mechanism

International Nuclear Information System (INIS)

Gormin, D.

1989-01-01

Using picosecond transient absorption studies, it is shown that the twisted intramolecular charge-transfer state (TICT) and the excited intramolecular proton-transfer state (ESIPT or PT) of specific aminosalicylates both contribute to the long-wavelength fluorescence band, F 2 , observed as an unresolved band to the red of the normal fluorescence band, F 1 . The transient absorption band for 2-hydroxy-4-(dimethylamino)benzoic acid methyl ester (PDASE) is shown to be a composite of the two excited-state absorption modes: S n double-prime(TICT) left-arrow S 1 double-prime (TICT) and S n '(PT)left-arrow S 1 '(PT). This corroborates previous steady-state fluorescence studies of the unresolved F 2 band. The assignments are based on comparison with the excited-state absorption spectra of various substituted aminosalicylates in polar and nonpolar solvents

Development of ultrafiltration and inorganic adsorbents: January--March 1977

International Nuclear Information System (INIS)

Koenst, J.W. Jr.

1977-01-01

Ultrafiltration media with and without the assistance of bone char filters were evaluated to determine their effectiveness in removing radionuclides from contaminated solutions. Precipitants, resin, adsorbents, and inorganic adsorbents were studied to determine their effectiveness in decontaminating solutions. A study of the effects of radiation on ultrafiltration media was initiated. An ultrafiltration media pilot plant was ordered and is being installed

Live microbial cells adsorb Mg2+ more effectively than lifeless organic matter

Science.gov (United States)

Qiu, Xuan; Yao, Yanchen; Wang, Hongmei; Duan, Yong

2018-03-01

The Mg2+ content is essential in determining different Mg-CaCO3 minerals. It has been demonstrated that both microbes and the organic matter secreted by microbes are capable of allocating Mg2+ and Ca2+ during the formation of Mg-CaCO3, yet detailed scenarios remain unclear. To investigate the mechanism that microbes and microbial organic matter potentially use to mediate the allocation of Mg2+ and Ca2+ in inoculating systems, microbial mats and four marine bacterial strains ( Synechococcus elongatus, Staphylococcus sp., Bacillus sp., and Desulfovibrio vulgaris) were incubated in artificial seawater media with Mg/Ca ratios ranging from 0.5 to 10.0. At the end of the incubation, the morphology of the microbial mats and the elements adsorbed on them were analyzed using scanning electronic microscopy (SEM) and energy diffraction spectra (EDS), respectively. The content of Mg2+ and Ca2+ adsorbed by the extracellular polysaccharide substances (EPS) and cells of the bacterial strains were analyzed with atomic adsorption spectroscopy (AAS). The functional groups on the surface of the cells and EPS of S. elongatus were estimated using automatic potentiometric titration combined with a chemical equilibrium model. The results show that live microbial mats generally adsorb larger amounts of Mg2+ than Ca2+, while this rarely is the case for autoclaved microbial mats. A similar phenomenon was also observed for the bacterial strains. The living cells adsorb more Mg2+ than Ca2+, yet a reversed trend was observed for EPS. The functional group analysis indicates that the cell surface of S. elongatus contains more basic functional groups (87.24%), while the EPS has more acidic and neutral functional groups (83.08%). These features may be responsible for the different adsorption behavior of Mg2+ and Ca2+ by microbial cells and EPS. Our work confirms the differential Mg2+ and Ca2+ mediation by microbial cells and EPS, which may provide insight into the processes that microbes use to

Elementary spin excitations in ultrathin itinerant magnets

Energy Technology Data Exchange (ETDEWEB)

Zakeri, Khalil, E-mail: zakeri@mpi-halle.de

2014-12-10

Elementary spin excitations (magnons) play a fundamental role in condensed matter physics, since many phenomena e.g. magnetic ordering, electrical (as well as heat) transport properties, ultrafast magnetization processes, and most importantly electron/spin dynamics can only be understood when these quasi-particles are taken into consideration. In addition to their fundamental importance, magnons may also be used for information processing in modern spintronics. Here the concept of spin excitations in ultrathin itinerant magnets is discussed and reviewed. Starting with a historical introduction, different classes of magnons are introduced. Different theoretical treatments of spin excitations in solids are outlined. Interaction of spin-polarized electrons with a magnetic surface is discussed. It is shown that, based on the quantum mechanical conservation rules, a magnon can only be excited when a minority electron is injected into the system. While the magnon creation process is forbidden by majority electrons, the magnon annihilation process is allowed instead. These fundamental quantum mechanical selection rules, together with the strong interaction of electrons with matter, make the spin-polarized electron spectroscopies as appropriate tools to excite and probe the elementary spin excitations in low-dimensional magnets e.g ultrathin films and nanostructures. The focus is put on the experimental results obtained by spin-polarized electron energy loss spectroscopy and spin-polarized inelastic tunneling spectroscopy. The magnon dispersion relation, lifetime, group and phase velocity measured using these approaches in various ultrathin magnets are discussed in detail. The differences and similarities with respect to the bulk excitations are addressed. The role of the temperature, atomic structure, number of atomic layers, lattice strain, electronic complexes and hybridization at the interfaces are outlined. A possibility of simultaneous probing of magnons and phonons

Surface-enhanced vibrational spectroscopy of B vitamins: what is the effect of SERS-active metals used?

Science.gov (United States)

Kokaislová, A; Matějka, P

2012-05-01

Surface-enhanced Raman scattering (SERS) spectroscopy and surface-enhanced infrared absorption (SEIRA) spectroscopy are analytical tools suitable for the detection of small amounts of various analytes adsorbed on metal surfaces. During recent years, these two spectroscopic methods have become increasingly important in the investigation of adsorption of biomolecules and pharmaceuticals on nanostructured metal surfaces. In this work, the adsorption of B-group vitamins pyridoxine, nicotinic acid, folic acid and riboflavin at electrochemically prepared gold and silver substrates was investigated using Fourier transform SERS spectroscopy at an excitation wavelength of 1,064 nm. Gold and silver substrates were prepared by cathodic reduction on massive platinum targets. In the case of gold substrates, oxidation-reduction cycles were applied to increase the enhancement factor of the gold surface. The SERS spectra of riboflavin, nicotinic acid, folic acid and pyridoxine adsorbed on silver substrates differ significantly from SERS spectra of these B-group vitamins adsorbed on gold substrates. The analysis of near-infrared-excited SERS spectra reveals that each of B-group vitamin investigated interacts with the gold surface via a different mechanism of adsorption to that with the silver surface. In the case of riboflavin adsorbed on silver substrate, the interpretation of surface-enhanced infrared absorption (SEIRA) spectra was also helpful in investigation of the adsorption mechanism.

Can Measured Synergy Excitations Accurately Construct Unmeasured Muscle Excitations?

Science.gov (United States)

Bianco, Nicholas A; Patten, Carolynn; Fregly, Benjamin J

2018-01-01

Accurate prediction of muscle and joint contact forces during human movement could improve treatment planning for disorders such as osteoarthritis, stroke, Parkinson's disease, and cerebral palsy. Recent studies suggest that muscle synergies, a low-dimensional representation of a large set of muscle electromyographic (EMG) signals (henceforth called "muscle excitations"), may reduce the redundancy of muscle excitation solutions predicted by optimization methods. This study explores the feasibility of using muscle synergy information extracted from eight muscle EMG signals (henceforth called "included" muscle excitations) to accurately construct muscle excitations from up to 16 additional EMG signals (henceforth called "excluded" muscle excitations). Using treadmill walking data collected at multiple speeds from two subjects (one healthy, one poststroke), we performed muscle synergy analysis on all possible subsets of eight included muscle excitations and evaluated how well the calculated time-varying synergy excitations could construct the remaining excluded muscle excitations (henceforth called "synergy extrapolation"). We found that some, but not all, eight-muscle subsets yielded synergy excitations that achieved >90% extrapolation variance accounted for (VAF). Using the top 10% of subsets, we developed muscle selection heuristics to identify included muscle combinations whose synergy excitations achieved high extrapolation accuracy. For 3, 4, and 5 synergies, these heuristics yielded extrapolation VAF values approximately 5% lower than corresponding reconstruction VAF values for each associated eight-muscle subset. These results suggest that synergy excitations obtained from experimentally measured muscle excitations can accurately construct unmeasured muscle excitations, which could help limit muscle excitations predicted by muscle force optimizations.

Excited, bound and resonant positron-atom systems

Energy Technology Data Exchange (ETDEWEB)

Bromley, M W J [Department of Physics and Computational Science Research Center, San Diego State University, San Diego CA 92182 (United States); Mitroy, J, E-mail: mbromley@physics.sdsu.ed [ARC Centre for Antimatter-Matter Studies and Faculty of Education, Health and Science, Charles Darwin University, Darwin NT 0909 (Australia)

2010-01-01

Calculations have demonstrated that eleven neutral atoms can bind positrons, while many more can bind positronium. This is a short review of recent progress made in understanding some of the underlying mechanisms. The emphasis here being on configuration interaction calculations with excited state configurations. These have demonstrated the existence of a {sup 2}P{sup o} excited state of e{sup +}Ca, which consists predominantly of a positronium cluster orbiting the Ca{sup +} ion in the L = 1 partial wave. Preliminary results are presented of excited state positron binding to a model alkali atom, where the excited {sup 1}P{sup o} states are stable over a limited region. Implications for the unnatural parity, {sup 2,4}S{sup o}, states of PsH, LiPs, NaPs and KPs are also discussed. The e{sup +}Mg, e{sup +}Cu, e{sup +}Zn and e{sup +}Cd systems show a lack of a {sup 2}P{sup o} excited state, each instead possessing a low-energy p-wave shape resonance of varying strength.

Black Sprayable Molecular Adsorber Coating Project

Data.gov (United States)

National Aeronautics and Space Administration — The main objective of this technology project is to develop, optimize, and flight qualify a black version of the molecular adsorber coating and a conductive version...

Dissociative Excitation of Thymine by Electron Impact

Science.gov (United States)

McConkey, William; Tiessen, Collin; Hein, Jeffrey; Trocchi, Joshuah; Kedzierski, Wladek

2014-05-01

A crossed electron-gas beam system coupled to a VUV spectrometer has been used to investigate the dissociation of thymine (C5H6N2O2) into excited atomic fragments in the electron-impact energy range from threshold to 375 eV. A special stainless steel oven is used to vaporize the thymine and form it into a beam where it is intersected by a magnetically collimated electron beam, typical current 50 μA. The main features in the spectrum are the H Lyman series lines. The probability of extracting excited C or N atoms from the ring is shown to be very small. In addition to spectral data, excitation probability curves as a function of electron energy will be presented for the main emission features. Possible dissociation channels and excitation mechanisms in the parent molecule will be discussed. The authors thank NSERC (Canada) for financial support.

Adsorption removal of hydrogen sulfide gas. IV. Characteristics of adsorbents for the adsorption removal of hydrogen sulfide gas

Energy Technology Data Exchange (ETDEWEB)

Boki, K

1974-10-25

The amount of hydrogen sulfide gas adsorbed was affected by the surface properties (surface pH, acid strength, acid amount, and basic amount), the surface structure (pore volume), and the surface form (scanning electron microscopic observation) of 32 tested adsorbents. In general, the amount adsorption increased in the following order, amount of H/sub 2/S adsorbed on the silicate adsorbents, on the active carbon adsorbents, and on the zeolite adsorbents. The amount of H/sub 2/S adsorbed on magnesium silicate and silica gel adsorbents was mainly affected by the surface structure, and the amount adsorbed on the aluminum silicate adsorbents was affected by the distinctions on the surface forms of the adsorbents. The amount of H/sub 2/S adsorbed on 10 kinds of active carbon was determined by the surface properties and the surface structures of the adsorbents. The amount adsorbed on 12 kinds of zeolites was determined by either the surface properties or by the surface structures of the adsorbents. The amount of H/sub 2/S adsorbed on the silicate, active carbon, and zeolite adsorbents interacted with the heat of adsorption, and among the same kinds of adsorbents, the amount adsorbed was linearly related to the heat of adsorption.

Retention of radium from thermal waters on sand filters and adsorbents

Energy Technology Data Exchange (ETDEWEB)

Elejalde, C. [Dpto. de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria, Alameda de Urquijo s/n, 48013 Bilbao (Spain)]. E-mail: inpelsac@bi.ehu.es; Herranz, M. [Dpto. de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Idoeta, R. [Dpto. de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Legarda, F. [Dpto. de Ingenieria Nuclear y Mecanica de Fluidos, Escuela Tecnica Superior de Ingenieria, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Romero, F. [Dpto. de Ingenieria Quimica y del Medio Ambiente, Escuela Tecnica Superior de Ingenieria, Alameda de Urquijo s/n, 48013 Bilbao (Spain); Baeza, A. [Dpto. de Fisica, Facultad de Veterinaria, Universidad de Extremadura, Avda. Universidad s/n, 10071 Caceres (Spain)

2007-06-18

This study was focussed on laboratory experiences of retention of radium from one thermal water on sand filters and adsorbents, trying to find an easy method for the elimination in drinkable waters polluted with this natural radio-nuclide. A thermal water from Cantabria (Spain) was selected for this work. Retention experiences were made with columns of 35 mm of diameter containing 15 cm layers of washed river sand or 4 cm layers of zeolite A3, passing known volumes of thermal water at flows between 4 and 40 ml/min with control of the retained radium by determining the amount in the water after the treatment. The statistical analysis of data suggests that retention depends on the flow and the volume passed through the columns. As additional adsorbents were used kaolin and a clay rich in illite. Jar-test experiences were made agitating known weights of adsorbents with the selected thermal water, with addition of flocculants and determination of radium in filtrated water after the treatment. Data suggest that retention is related to the weight of adsorbent used, but important quantities of radium seem remain in solution for higher amounts of adsorbents, according to the statistical treatment of data. The elution of retained radium from columns or adsorbents, previously used in experiences, should be the aim of a future research.

Retention of radium from thermal waters on sand filters and adsorbents

International Nuclear Information System (INIS)

Elejalde, C.; Herranz, M.; Idoeta, R.; Legarda, F.; Romero, F.; Baeza, A.

2007-01-01

This study was focussed on laboratory experiences of retention of radium from one thermal water on sand filters and adsorbents, trying to find an easy method for the elimination in drinkable waters polluted with this natural radio-nuclide. A thermal water from Cantabria (Spain) was selected for this work. Retention experiences were made with columns of 35 mm of diameter containing 15 cm layers of washed river sand or 4 cm layers of zeolite A3, passing known volumes of thermal water at flows between 4 and 40 ml/min with control of the retained radium by determining the amount in the water after the treatment. The statistical analysis of data suggests that retention depends on the flow and the volume passed through the columns. As additional adsorbents were used kaolin and a clay rich in illite. Jar-test experiences were made agitating known weights of adsorbents with the selected thermal water, with addition of flocculants and determination of radium in filtrated water after the treatment. Data suggest that retention is related to the weight of adsorbent used, but important quantities of radium seem remain in solution for higher amounts of adsorbents, according to the statistical treatment of data. The elution of retained radium from columns or adsorbents, previously used in experiences, should be the aim of a future research

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.

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.

Foam-based adsorbents having high adsorption capacities for recovering dissolved metals and methods thereof

Science.gov (United States)

Janke, Christopher J.; Dai, Sheng; Oyola, Yatsandra

2015-06-02

Foam-based adsorbents and a related method of manufacture are provided. The foam-based adsorbents include polymer foam with grafted side chains and an increased surface area per unit weight to increase the adsorption of dissolved metals, for example uranium, from aqueous solutions. A method for forming the foam-based adsorbents includes irradiating polymer foam, grafting with polymerizable reactive monomers, reacting with hydroxylamine, and conditioning with an alkaline solution. Foam-based adsorbents formed according to the present method demonstrated a significantly improved uranium adsorption capacity per unit weight over existing adsorbents.

An experimental study of the effects of adsorbing and non-adsorbing gases on friction and permeability evolution in clay-rich fault gouge

Science.gov (United States)

Lisabeth, H. P.; Zoback, M. D.

2017-12-01

Understanding the flow of fluids through fractures in clay-rich rocks is fundamental to a number of geoengineering enterprises, including development of unconventional hydrocarbon resources, nuclear waste storage and geological carbon sequestration. High clay content tends to make rocks plastic, low-porosity and anisotropic. In addition, some gasses adsorb to clay mineral surfaces, resulting in swelling and concomitant changes in physical properties. These complexities can lead to coupled behaviors that render prediction of fluid behavior in the subsurface difficult. We present the results of a suite of triaxial experiments on binary mixtures of quartz and illite grains to separate and quantify the effects of hydrostatic pressure, differential stress, clay content and gas chemistry on the evolution of mechanical and hydraulic characteristics of the gouge material during deformation. Tests are run on saw-cut samples prepared with gouge at 20 MPa confining pressure, 10 MPa pore pressure and at room temperature. Argon or carbon dioxide is used as pore fluid. Sample permeability, stress and strain are monitored continuously during hydrostatic and axial deformation. We find that pressure and shearing both lead to reductions in permeability. Adsorbing gas leads to swelling and promotes permeability reduction, but appears to have no effect on frictional properties. These results indicate that the seal integrity of clay-rich caprocks may not be compromised by shear deformation, and that depletion and shear deformation of unconventional reservoirs is expected to result in production declines.

Studies of spin excitations with electromagnetic and hadronic probes

International Nuclear Information System (INIS)

Lindgren, R.A.; Petrovich, F.

1982-01-01

Excitation of unnatural parity states, predominantly of high spin, using electromagnetic and hadronic probes, is discussed. Spectroscopic strengths are deduced from studies of (e,e'), (p,p'), (π.π'), and (p,n) for states whose doorway is the stretched particle-hole configuration. These levels are excited primarily through the isovector electromagnetic-nucleon magnetization coupling, nucleon-nucleon tensor coupling, and pion-nucleon spin-orbit coupling. The extracted isovector spectroscopic strength is typically 38% of the extreme single particle-hole model and about 66% of that predicted by more realistic nuclear structure calculations. The observed isoscalar strength is only about one half of the isovector strength. The results obtained with the three different probes are quite consistent. The primary conclusion is that the missing strength for these high spin excitations is at least as large as for the low spin M1 and GT excitations. This implies the existence of other important quenching mechanisms since the Δ-N -1 mechanism involved in the discussion of the low spin excitation affects only the isovector transitions and contributes little to high spin excitations. A method for using (e,e') and π + /π - cross section ratios to separate and determine the absolute isoscalar and isovector spin densities for T 0 to T 0 transitions in N is not equal to Z nuclei is also discussed and some comments on extracting information from (e,e') and (p,p') studies at high q on low spin 1 + and 2 - levels are presented. 78 references

Cryogenic exciter

Science.gov (United States)

Bray, James William [Niskayuna, NY; Garces, Luis Jose [Niskayuna, NY

2012-03-13

The disclosed technology is a cryogenic static exciter. The cryogenic static exciter is connected to a synchronous electric machine that has a field winding. The synchronous electric machine is cooled via a refrigerator or cryogen like liquid nitrogen. The static exciter is in communication with the field winding and is operating at ambient temperature. The static exciter receives cooling from a refrigerator or cryogen source, which may also service the synchronous machine, to selected areas of the static exciter and the cooling selectively reduces the operating temperature of the selected areas of the static exciter.

Natural waste materials containing chitin as adsorbents for textile dyestuffs: batch and continuous studies.

Science.gov (United States)

Figueiredo, S A; Loureiro, J M; Boaventura, R A

2005-10-01

In this work three natural waste materials containing chitin were used as adsorbents for textile dyestuffs, namely the Anodonta (Anodonta cygnea) shell, the Sepia (Sepia officinalis) and the Squid (Loligo vulgaris) pens. The selected dyestuffs were the Cibacron green T3G-E (CI reactive green 12), and the Solophenyl green BLE 155% (CI direct green 26), both from CIBA, commonly used in cellulosic fibres dyeing, the most used fibres in the textile industry. Batch equilibrium studies showed that the materials' adsorption capacities increase after a simple and inexpensive chemical treatment, which increases their porosity and chitin relative content. Kinetic studies suggested the existence of a high internal resistance in both systems. Fixed bed column experiments performed showed an improvement in adsorbents' behaviour after chemical treatment. However, in the column experiments, the biodegradation was the main mechanism of dyestuff removal, allowing the materials' bioregeneration. The adsorption was strongly reduced by the pore clogging effect of the biomass. The deproteinised Squid pen (grain size 0.500-1.41 mm) is the adsorbent with highest adsorption capacity (0.27 and 0.037 g/g, respectively, for the reactive and direct dyestuffs, at 20 degrees C), followed by the demineralised Sepia pen and Anodonta shell, behaving like pure chitin in all experiments, but showing inferior performances than the granular activated carbon tested in the column experiments.

Experimental study on the basic characteristics of a novel silica-based CMPO adsorbent

International Nuclear Information System (INIS)

Wei, Yuezhou; Arai, Tsuyoshi; Zhang, Anyun; Hoshi, Harutaka; Koma, Yoshikazu; Watanabe, Masayuki

2002-01-01

In order to establish the extraction chromatography process for recovery of minor actinides from HLLW with a novel silica-based CMPO (octyl(phenyl)-N, N-diisobutylcarbamoylmethylphosphine oxide) adsorbent, some basic characteristics, such as dissolving behavior of CMPO from the adsorbent, thermal decomposition of the adsorbent and treatment method of organic wastes, were examined. It was found that the leakage of CMPO from the adsorbent in contact with an aqueous solution is the result of the solubility of CMPO in the solution. About 40-50 ppm of CMPO constantly leaked into the effluent from the adsorbent packed column using 0.01 M (M=mol/dm 3 ) HNO 3 as a mobile phase. The leakage of CMPO from the adsorbent could be effectively depressed with the utilization of the aqueous solution saturated by CMPO. TG-DTA thermal analysis results indicate that CMPO in the adsorbent decomposed at 20degC and the SDB-polymer at 290degC. The impregnated CMPO could be completely dissolved out from the support with acetone. Furthermore, the organic wastes such as CMPO, oxalic acid and DTPA those come from the elution procedure could be effectively decomposed with the Fenton reagent. (author)

Band mapping of surface states vs. adsorbate coverage

International Nuclear Information System (INIS)

Rotenberg, E.; Kevan, S.D.; Denlinger, J.D.; Chung, Jin-Wook

1997-01-01

The theory of electron bands, which arises from basic quantum mechanical principles, has been the cornerstone of solid state physics for over 60 years. Simply put, an energy band is an electron state in a solid whose energy varies with its momentum (similar to, but with a more complicated dependence than, how a free electron's energy is proportional to its momentum squared). Much attention over the last 15 years has been given to the study of band structure of surfaces and interfaces, especially as the applications of these two-dimensional systems have become increasingly important to industry and science. The ultraESCA endstation at beamline 7.01 at the Advanced Light Source was developed for very high-energy - (∼50 meV) and angular - ( 12 photons/sec) makes the detailed study of the evolution of bands possible. The authors are interested in learning how, when one forms a chemical bond between a metal and an overlaying atom or molecule, the resulting charge transfer to or from the adsorbate affects the surface bands. In some cases of interest, intermediate coverages lead to different band structure than at the extremes of clean and saturated surfaces. Surfaces of tungsten are particularly interesting, as their atomic geometry has been shown to be exquisitely sensitive to both the surface vibrational and electronic properties. In this study, the authors looked at the surface bands of tungsten ((110) surface), as a function both of coverage and mass of overlaying atoms. The adsorbed atoms were hydrogen and the alkali atoms lithium and cesium

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.

Green Adsorbents for Wastewaters: A Critical Review

Science.gov (United States)

Kyzas, George Z.; Kostoglou, Margaritis

2014-01-01

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. PMID:28788460

Oil palm biomass-based adsorbents for the removal of water pollutants--a review.

Science.gov (United States)

Ahmad, Tanweer; Rafatullah, Mohd; Ghazali, Arniza; Sulaiman, Othman; Hashim, Rokiah

2011-07-01

This article presents a review on the role of oil palm biomass (trunks, fronds, leaves, empty fruit bunches, shells, etc.) as adsorbents in the removal of water pollutants such as acid and basic dyes, heavy metals, phenolic compounds, various gaseous pollutants, and so on. Numerous studies on adsorption properties of various low-cost adsorbents, such as agricultural wastes and its based activated carbons, have been reported in recent years. Studies have shown that oil palm-based adsorbent, among the low-cost adsorbents mentioned, is the most promising adsorbent for removing water pollutants. Further, these bioadsorbents can be chemically modified for better efficiency and can undergo multiple reuses to enhance their applicability at an industrial scale. It is evident from a literature survey of more than 100 recent papers that low-cost adsorbents have demonstrated outstanding removal capabilities for various pollutants. The conclusion is been drawn from the reviewed literature, and suggestions for future research are proposed.

Cost analysis of seawater uranium recovered by a polymeric adsorbent system

International Nuclear Information System (INIS)

Schneider, E.; Lindner, H.; Sachde, D.; Flicker, M.

2014-01-01

In tandem with its adsorbent development and marine testing efforts, the United States Department of Energy, Office of Nuclear Energy, routinely updates and expands its cost analysis of technologies for extracting uranium from seawater. If informed by repeatable data from field tests, a rigorous cost analysis can convincingly establish seawater uranium as a “backstop” to conventional uranium resources. A backstop provides an essentially unlimited supply of an otherwise exhaustible resource. Its role is to remove the uncertainty around the long-term sustainability of the resource. The cost analysis ultimately aims to demonstrate a uranium production cost that is sustainable for the nuclear power industry, with no insurmountable technical or environmental roadblocks. It is also a tool for guiding further R&D, identifying inputs and performance factors where further development would offer the greatest reduction in costs and/or uncertainties. A life cycle discounted cash flow methodology is used to calculate the uranium production cost and its uncertainty from the costs of fundamental inputs including chemicals and materials, labor, equipment, energy carriers and facilities. The inputs themselves are defined by process flow models of the adsorbent fabrication and grafting, mooring at sea, recovery, and elution and purification steps in the seawater uranium recovery process. Pacific Northwest National Laboratory (PNNL) has carried out marine tests of the Oak Ridge National Laboratory amidoxime grafted polymer adsorbent in natural seawater. Multiple test campaigns demonstrated that after 60 days of immersion the uranium uptake averaged 3090 ± 310 μg U/g of adsorbent. Past ocean experiments on similar material by the Japan Atomic Energy Agency (JAEA) demonstrated that the adsorbent may be used in the sea six times before being replaced, with 5% uptake degradation per reuse. The mooring and recovery system envisioned for the adsorbent is similar to one proposed by

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

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...

Evaluating of arsenic(V) removal from water by weak-base anion exchange adsorbents.

Science.gov (United States)

Awual, M Rabiul; Hossain, M Amran; Shenashen, M A; Yaita, Tsuyoshi; Suzuki, Shinichi; Jyo, Akinori

2013-01-01

Arsenic contamination of groundwater has been called the largest mass poisoning calamity in human history and creates severe health problems. The effective adsorbents are imperative in response to the widespread removal of toxic arsenic exposure through drinking water. Evaluation of arsenic(V) removal from water by weak-base anion exchange adsorbents was studied in this paper, aiming at the determination of the effects of pH, competing anions, and feed flow rates to improvement on remediation. Two types of weak-base adsorbents were used to evaluate arsenic(V) removal efficiency both in batch and column approaches. Anion selectivity was determined by both adsorbents in batch method as equilibrium As(V) adsorption capacities. Column studies were performed in fixed-bed experiments using both adsorbent packed columns, and kinetic performance was dependent on the feed flow rate and competing anions. The weak-base adsorbents clarified that these are selective to arsenic(V) over competition of chloride, nitrate, and sulfate anions. The solution pH played an important role in arsenic(V) removal, and a higher pH can cause lower adsorption capacities. A low concentration level of arsenic(V) was also removed by these adsorbents even at a high flow rate of 250-350 h(-1). Adsorbed arsenic(V) was quantitatively eluted with 1 M HCl acid and regenerated into hydrochloride form simultaneously for the next adsorption operation after rinsing with water. The weak-base anion exchange adsorbents are to be an effective means to remove arsenic(V) from drinking water. The fast adsorption rate and the excellent adsorption capacity in the neutral pH range will render this removal technique attractive in practical use in chemical industry.

Ionization and excitation of lithium atoms by fast charged particle impact: identification of mechanisms for double K-shell vacancy production as a function of the projectile charge and velocity

International Nuclear Information System (INIS)

Rangama, J.

2002-11-01

Ionization and excitation of lithium atoms by fast charged particle impact: identification of mechanisms for double K-shell vacancy production as a function of projectile charge and velocity. Auger electron spectroscopy is used for an experimental investigation of ionization and excitation of lithium atoms by ions (Kr34 + and Ar18 + ) and electrons at high impact velocities (from 6 to 60 a.u.). In particular, relative contributions of the mechanisms responsible for lithium K-shell ionization-excitation are determined for various projectile charges Zp and velocities vp. A large range of perturbation parameters |Zp|/vp is explored (|Zp|/vp = 0,05 - 0,7 a.u.). From single K-shell excitation results, it appears that the projectile-electron interaction gives mainly rise to a dipole-like transition 1s -> np Concerning K-shell ionization-excitation, the separation of the TS2 (two independent projectile-electron interactions) and TS1 (one projectile-electron interaction) mechanisms responsible for the formation of the 2snp 1,3P and 2sns 1,3S lithium states is performed. In TS1 process, the projectile-electron interaction can be followed by an electron-electron interaction (dielectronic process) or by an internal rearrangement of the residual target after a sudden potential change (shake process). From Born theory, ab initio calculations are performed. The good agreement between theoretical and experimental results confirms the mechanism identification. For the production of P states, TS1 is found to be strongly dominant for small |Zp|/vp values and TS2 is found to be most important for large |Zp|/vp values. Since P states cannot be formed significantly via a shake process, the TS1 and TS2 separation provides a direct signature of the dielectronic process. On the other hand, the TS1 process is shown to be the unique process for producing the S states. At the moment, only the shake aspect of the TS1 process can explain the fact that the 2s3s configuration is preferentially

Microporous carbonaceous adsorbents for CO2 separation via selective adsorption

KAUST Repository

Zhao, Yunfeng

2015-01-01

Selective adsorption of CO2 has important implications for many energy and environment-related processes, which require the separation of CO2 from other gases (e.g. N2 and CH4) with high uptakes and selectivity. The development of high-performance adsorbents is one of the most promising solutions to the success of these processes. The present review is focused on the state-of-the-art of carbon-based (carbonaceous) adsorbents, covering microporous inorganic carbons and microporous organic polymers, with emphasis on the correlation between their textural and compositional properties and their CO2 adsorption/separation performance. Special attention is given to the most recently developed materials that were not covered in previous reviews. We summarize various effective strategies (N-doping, surface functionalization, extra-framework ions, molecular design, and pore size engineering) for enhancing the CO2 adsorption capacity and selectivity of carbonaceous adsorbents. Our discussion focuses on CO2/N2 separation and CO2/CH4 separation, while including an introduction to the methods and criteria used for evaluating the performance of the adsorbents. Critical issues and challenges regarding the development of high-performance adsorbents as well as some overlooked facts and misconceptions are also discussed, with the aim of providing important insights into the design of novel carbonaceous porous materials for various selective adsorption based applications. This journal is © The Royal Society of Chemistry.

Adsorption behavior of lithium from seawater using manganese oxide adsorbent

International Nuclear Information System (INIS)

Wajima, Takaaki; Munakata, Kenzo; Uda, Tatsuhiko

2012-01-01

The deuterium-tritium (D-T) fusion reactor system is expected to provide the main source of electricity in the future. Large amounts of lithium will be required, dependent on the reactor design concept, and alternative resources should be found to provide lithium inventories for nuclear fusion plants. Seawater has recently become an attractive source of this element and the separation and recovery of lithium from seawater by co-precipitation, solvent extraction and adsorption have been investigated. Amongst these techniques, the adsorption method is suitable for recovery of lithium from seawater, because certain inorganic ion-exchange materials, especially spinel-type manganese oxides, show extremely high selectivity for the lithium ion. In this study, we prepared a lithium adsorbent (HMn 2 O 4 ) by elution of spinel-type lithium di-manganese-tetra-oxide (LiMn 2 O 4 ) and examined the kinetics of the adsorbent for lithium ions in seawater using a pseudo-second-order kinetic model. The intermediate, LiMn 2 O 4 , can be synthesized from LiOH·H 2 O and Mn 3 O 4 , from which the lithium adsorbent can subsequently be prepared via acid treatment., The adsorption kinetics become faster and the amount of lithium adsorbed on the adsorbent increases with increasing solution temperature. The thermodynamic values, ΔG 0 , ΔH 0 and ΔS 0 , indicate that adsorption is an endothermic and spontaneous process. (author)

Kinetics of conformational changes of fibronectin adsorbed onto model surfaces.

Science.gov (United States)

Baujard-Lamotte, L; Noinville, S; Goubard, F; Marque, P; Pauthe, E

2008-05-01

Fibronectin (FN), a large glycoprotein found in body fluids and in the extracellular matrix, plays a key role in numerous cellular behaviours. We investigate FN adsorption onto hydrophilic bare silica and hydrophobic polystyrene (PS) surfaces using Fourier transform infrared spectroscopy-attenuated total reflection (FTIR-ATR) in aqueous medium. Adsorption kinetics using different bulk concentrations of FN were followed for 2h and the surface density of adsorbed FN and its time-dependent conformational changes were determined. When adsorption occurs onto the hydrophilic surface, FN molecules keep their native conformation independent of the adsorption conditions, but the amount of adsorbed FN increases with time and the bulk concentration. Although the protein surface density is the same on the hydrophobic PS surface, this has a strong impact on the average conformation of the adsorbed FN layer. Indeed, interfacial hydration changes induced by adsorption onto the hydrophobic surface lead to a decrease in unhydrated beta-sheet content and cause an increase in hydrated beta-strand and hydrated random domain content of adsorbed FN. This conformational change is mainly dependent on the bulk concentration. Indeed, at low bulk concentrations, the secondary structures of adsorbed FN molecules undergo strong unfolding, allowing an extended and hydrated conformation of the protein. At high bulk concentrations, the molecular packing reduces the unfolding of the stereoregular structures of the FN molecules, preventing stronger spreading of the protein.

Prefrontal Neuronal Excitability Maintains Cocaine-Associated Memory During Retrieval

Directory of Open Access Journals (Sweden)

James M. Otis

2018-06-01

Full Text Available Presentation of drug-associated cues provokes craving and drug seeking, and elimination of these associative memories would facilitate recovery from addiction. Emotionally salient memories are maintained during retrieval, as particular pharmacologic or optogenetic perturbations of memory circuits during retrieval, but not after, can induce long-lasting memory impairments. For example, in rats, inhibition of noradrenergic beta-receptors, which control intrinsic neuronal excitability, in the prelimbic medial prefrontal cortex (PL-mPFC can cause long-term memory impairments that prevent subsequent cocaine-induced reinstatement. The physiologic mechanisms that allow noradrenergic signaling to maintain drug-associated memories during retrieval, however, are unclear. Here we combine patch-clamp electrophysiology ex vivo and behavioral neuropharmacology in vivo to evaluate the mechanisms that maintain drug-associated memory during retrieval in rats. Consistent with previous studies, we find that cocaine experience increases the intrinsic excitability of pyramidal neurons in PL-mPFC. In addition, we now find that this intrinsic plasticity positively predicts the retrieval of a cocaine-induced conditioned place preference (CPP memory, suggesting that such plasticity may contribute to drug-associated memory retrieval. In further support of this, we find that pharmacological blockade of a cAMP-dependent signaling cascade, which allows noradrenergic signaling to elevate neuronal excitability, is required for memory maintenance during retrieval. Thus, inhibition of PL-mPFC neuronal excitability during memory retrieval not only leads to long-term deficits in the memory, but this memory deficit provides protection against subsequent cocaine-induced reinstatement. These data reveal that PL-mPFC intrinsic neuronal excitability maintains a cocaine-associated memory during retrieval and suggest a unique mechanism whereby drug-associated memories could be targeted

Preparation and adsorption characteristics for heavy metals of active silicon adsorbent from leaching residue of lead-zinc tailings.

Science.gov (United States)

Lei, Chang; Yan, Bo; Chen, Tao; Xiao, Xian-Ming

2018-05-19

To comprehensively reuse the leaching residue obtained from lead-zinc tailings, an active silicon adsorbent (ASA) was prepared from leaching residue and studied as an adsorbent for copper(II), lead(II), zinc(II), and cadmium(II) in this paper. The ASA was prepared by roasting the leaching residue with either a Na 2 CO 3 /residue ratio of 0.6:1 at 700 °C for 1 h or a CaCO 3 /residue ratio of 0.8:1 at 800 °C for 1 h. Under these conditions, the available SiO 2 content of the ASA was more than 20%. The adsorption behaviors of the metal ions onto the ASA were investigated and the Langmuir, Freundlich, and Dubinin-Radushkevich isotherm models were used to analyze the adsorption isotherm. The result showed that the maximum adsorption capacities of copper(II), lead(II), cadmium(II), and zinc(II) calculated by the Langmuir model were 3.40, 2.83, 0.66, and 0.62 mmol g -1 , respectively. The FT-IR spectra of the ASA and the mean free adsorption energies indicated that ion exchange was the mechanism of copper(II), lead(II), and cadmium(II) adsorption and that chemical reaction was the mechanism of zinc(II) adsorption. These results provide a method for reusing the leaching residue obtained from lead-zinc tailings and show that the ASA is an effective adsorbent for heavy metal pollution remediation.

Magnetic copper-based metal organic framework as an effective and recyclable adsorbent for removal of two fluoroquinolone antibiotics from aqueous solutions.

Science.gov (United States)

Wu, Gege; Ma, Jiping; Li, Shuang; Guan, Jing; Jiang, Bo; Wang, Liyan; Li, Jinhua; Wang, Xiaoyan; Chen, Lingxin

2018-05-30

Fe 3 O 4 /HKUST-1 magnetic copper based metal-organic frameworks (MOF) were synthesized by a simple and facile method and applied as an effective and recyclable adsorbent for the adsorptive removal of two widely used ciprofloxacin (CIP) and norfloxacin (NOR) fluoroquinolone antibiotics (FQAs) from aqueous solutions. Fe 3 O 4 /HKUST-1 was thoroughly characterized, and the major influence factors including solution pH, adsorbent amount and salt concentration were investigated. Compared to the reported adsorbents, Fe 3 O 4 /HKUST-1 has a very high adsorption rate, and it is found that CIP and NOR could be removed within 30 min. Moreover, the maximum adsorption capacities of the magnetic composites toward CIP and NOR reached as high as 538 mg g -1 and 513 mg g -1 , respectively, much higher than those of most of the reported adsorbents for these two FQAs. The saturation magnetization value of Fe 3 O 4 /HKUST-1 was 44 emu g -1 , which was sufficient for the separation of the Fe 3 O 4 /HKUST-1adsorbent from the aqueous solution by the application of an external magnetic field. Additionally, this magnetic material showed a good reusability with the adsorption capability decreasing only slightly after reuse for ten cycles. These results indicated that the magnetic composites Fe 3 O 4 /HKUST-1 may be a promising adsorbent in the decontamination of FQAs from wastewater due to its high adsorption capability, fast kinetics, easy separation from water, and excellent recyclability. The adsorption mechanism was proposed based on the effects of pH on adsorption and on the zeta potential of the adsorbent. For the adsorption of CIP and NOR by Fe 3 O 4 /HKUST-1, both electrostatic and π-π interactions may be important. Copyright © 2018 Elsevier Inc. All rights reserved.

Fate of Trace Organic Compounds in Granular Activated Carbon (GAC Adsorbers for Drinking Water Treatment

Directory of Open Access Journals (Sweden)

Alexander Sperlich

2017-06-01

Full Text Available Granular activated carbon (GAC adsorbers for drinking water treatment were operated for approx. 14 months and the breakthrough of dissolved organic carbon (DOC and trace organic chemicals (TOrCs was monitored. Effluent concentration profiles of gabapentin and valsartan acid increase already at throughputs of <10,000 BV. The corresponding breakthrough curves flatten out without reaching the influent concentration level. This strongly indicates biological degradation of these substances in the GAC adsorbers under aerobic conditions, contributing to a more efficient use of GAC. The observed biodegradation in pilot GAC adsorbers also confirms recent reports of biodegradation of gabapentin and valsartan acid during managed aquifer recharge. Oxypurinol is comparatively well adsorbed and no breakthrough was observed during the experimental period. Adsorption capacity and breakthrough characteristics of oxypurinol appear very similar to carbamazepine. Breakthrough of GAC adsorbers operated with drinking water was compared to those of groundwater-fed adsorbers. The results show, that it is generally advisable to use previously aerated influents for GAC fixed-bed adsorbers because this can substantially improve biological removal of otherwise poorly adsorbable compounds and ensure full GAC accessibility for adsorbates by avoiding the undesirable formation of inorganic precipitates on adsorption sites.

Laser pulses for coherent xuv Raman excitation

Science.gov (United States)

Greenman, Loren; Koch, Christiane P.; Whaley, K. Birgitta

2015-07-01

We combine multichannel electronic structure theory with quantum optimal control to derive femtosecond-time-scale Raman pulse sequences that coherently populate a valence excited state. For a neon atom, Raman target populations of up to 13% are obtained. Superpositions of the ground and valence Raman states with a controllable relative phase are found to be reachable with up to 4.5% population and arbitrary phase control facilitated by the pump pulse carrier-envelope phase. Analysis of the optimized pulse structure reveals a sequential mechanism in which the valence excitation is reached via a fast (femtosecond) population transfer through an intermediate resonance state in the continuum rather than avoiding intermediate-state population with simultaneous or counterintuitive (stimulated Raman adiabatic passage) pulse sequences. Our results open a route to coupling valence excitations and core-hole excitations in molecules and aggregates that locally address specific atoms and represent an initial step towards realization of multidimensional spectroscopy in the xuv and x-ray regimes.

Extraction of uranium from sea water by means of fibrous complex adsorbents

International Nuclear Information System (INIS)

Miyamatsu, Tokuhisa; Oguchi, Noboru; Kanchiku, Yoshihiko; Aoyagi, Takanobu

1982-01-01

Fibrous complex adsorbents for uranium extraction from sea water were prepared by introducing titanic acid or basic zinc carbonate as effective constituents into fibrous ion exchangers. A fibrous chelate type adsorbent was also tested. Among the adsorbents examined, the following ones demonstrated excellent properties for the recovery of uranium from sea water. a) A fibrous, weakly acidic cation exchanger was treated with titanyl sulfate in aqueous sulfuric acid solution, which was followed by neutralization to afford a fibrous adsorbent containing titanic acid (QC-1f(Ti)). The adsorption capacity for uranium in sea water was estimated by extrapolation to be 50μg-U/g-Ad or 1170 μg-U/g-Ti. b) A fibrous, strongly acidic cation exchanger was treated in a similar way to afford another type of fibrous adsorbent with titanic acid incorporated (QCS-Ti). The adsorption capacity was estimated by extrapolation to be 20-30 μg-U/g-Ad. (author)

Simulations of the Static Friction Due to Adsorbed Molecules

OpenAIRE

He, Gang; Robbins, Mark O.

2001-01-01

The static friction between crystalline surfaces separated by a molecularly thin layer of adsorbed molecules is calculated using molecular dynamics simulations. These molecules naturally lead to a finite static friction that is consistent with macroscopic friction laws. Crystalline alignment, sliding direction, and the number of adsorbed molecules are not controlled in most experiments and are shown to have little effect on the friction. Temperature, molecular geometry and interaction potenti...

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 to frustra...... 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.......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...

Oil adsorbing package, also procedure to remove oil from a water surface

Energy Technology Data Exchange (ETDEWEB)

1971-05-01

A method is given to remove oil from water to prevent water pollution. Use is made of an oil-adsorbing packet having a specific gravity which is lower than the specific gravity of water. The hull is manufactured from any material which is not a water-insoluble nonpolar material. The hull is partly permeable to water and encloses a solid oil-adsorbing compound having a large adsorbing surface. (10 claims)

Molecular-alignment dependence in the transfer excitation of H2

International Nuclear Information System (INIS)

Wang, Y.D.; McGuire, J.H.; Weaver, O.L.; Corchs, S.E.; Rivarola, R.D.

1993-01-01

Molecular-alignment effects in the transfer excitation of H 2 by high-velocity heavy ions are studied using a two-step mechanism with amplitudes evaluated from first-order perturbation theory. Two-electron transfer excitation is treated as a result of two independent collision processes (excitation and electron transfer). Cross sections for each one-electron subprocess as well as the combined two-electron process are calculated as functions of the molecular-alignment angle. Within the independent-electron approximation, the dynamic roles of electron excitation and transfer in conjunction with molecular alignment are explored. While both excitation and transfer cross sections may strongly depend on molecular alignment, it is electron transfer that is largely responsible for the molecular-alignment dependence in the transfer excitation process. Interpretation of some experimental observations based on this model will also be discussed

Adjuvant effects of aluminium hydroxide-adsorbed allergens and allergoids - differences in vivo and in vitro.

Science.gov (United States)

Heydenreich, B; Bellinghausen, I; Lund, L; Henmar, H; Lund, G; Adler Würtzen, P; Saloga, J

2014-06-01

Allergen-specific immunotherapy (SIT) is a clinically effective therapy for immunoglobulin (Ig)E-mediated allergic diseases. To reduce the risk of IgE-mediated side effects, chemically modified allergoids have been introduced. Furthermore, adsorbance of allergens to aluminium hydroxide (alum) is widely used to enhance the immune response. The mechanisms behind the adjuvant effect of alum are still not completely understood. In the present study we analysed the effects of alum-adsorbed allergens and allergoids on their immunogenicity in vitro and in vivo and their ability to activate basophils of allergic donors. Human monocyte derived dendritic cells (DC) were incubated with native Phleum pratense or Betula verrucosa allergen extract or formaldehyde- or glutaraldehyde-modified allergoids, adsorbed or unadsorbed to alum. After maturation, DC were co-cultivated with autologous CD4(+) T cells. Allergenicity was tested by leukotriene and histamine release of human basophils. Finally, in-vivo immunogenicity was analysed by IgG production of immunized mice. T cell proliferation as well as interleukin (IL)-4, IL-13, IL-10 and interferon (IFN)-γ production were strongly decreased using glutaraldehyde-modified allergoids, but did not differ between alum-adsorbed allergens or allergoids and the corresponding unadsorbed preparations. Glutaraldehyde modification also led to a decreased leukotriene and histamine release compared to native allergens, being further decreased by adsorption to alum. In vivo, immunogenicity was reduced for allergoids which could be partly restored by adsorption to alum. Our results suggest that adsorption of native allergens or modified allergoids to alum had no consistent adjuvant effect but led to a reduced allergenicity in vitro, while we observed an adjuvant effect regarding IgG production in vivo. © 2014 British Society for Immunology.

Adsorption of Mefenamic Acid From Water by Bentonite Poly urea formaldehyde Composite Adsorbent

Directory of Open Access Journals (Sweden)

Basma Abbas Abdel Majeed

2017-07-01

Full Text Available Poly urea formaldehyde –Bentonite (PUF-Bentonite composite was tested as new adsorbent for removal of mefenamic acid (MA from simulated wastewater in batch adsorption procedure. Developed a method for preparing poly urea formaldehyde gel in basic media by using condensation polymerization. Adsorption experiments were carried out as a function of water pH, temperature, contact time, adsorbent dose and initial MA concentration .Effect of sharing surface with other analgesic pharmaceuticals at different pH also studied. The adsorption of MA was found to be strongly dependent to pH. The Freundlich isotherm model showed a good fit to the equilibrium adsorption data. From Dubinin–Radushkevich model the mean free energy (E was calculated and the value of 5 KJ/mole indicated that the main mechanism governing the adsorption of MA on PUF-Bentonite composite was physical in nature. The kinetics of adsorption tested for first order, pseudo second order models and Elovich’s equation, results showed the adsorption followed the pseudo-second-order model

Investigations into the Reusability of Amidoxime-Based Polymeric Adsorbents for Seawater Uranium Extraction

Energy Technology Data Exchange (ETDEWEB)

Kuo, Li-Jung [Marine; Pan, Horng-Bin [Department; Wai, Chien M. [Department; Byers, Margaret F. [Nuclear; Schneider, Erich [Nuclear; Strivens, Jonathan E. [Marine; Janke, Christopher J. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831, United States; Das, Sadananda [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831, United States; Mayes, Richard T. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831, United States; Wood, Jordana R. [Marine; Schlafer, Nicholas [Marine; Gill, Gary A. [Marine

2017-09-29

The ability to re-use amidoxime-based polymeric adsorbents is a critical component in reducing the overall cost of the technology to extract uranium from seawater. This report describes an evaluation of adsorbent reusability in multiple re-use (adsorption/stripping) cycles in real seawater exposures with potassium bicarbonate (KHCO3) elution using several amidoxime-based polymeric adsorbents. The KHCO3 elution technique achieved ~100% recovery of uranium adsorption capacity in the first re-use. Subsequent re-uses showed significant drops in adsorption capacity. After the 4th re-use with the ORNL AI8 adsorbent, the 56-day adsorption capacity dropped to 28% of its original capacity. FTIR spectra revealed that there was a conversion of the amidoxime ligands to carboxylate groups during extended seawater exposure, becoming more significant with longer the exposure time. Ca and Mg adsorption capacities also increased with each re-use cycle supporting the hypothesis that long term exposure resulted in converting amidoxime to carboxylate, enhancing the adsorption of Ca and Mg. Shorter seawater exposure (adsorption/stripping) cycles (28 vs. 42 days) had higher adsorption capacities after re-use, but the shorter exposure cycle time did not produce an overall better performance in terms of cumulative exposure time. Recovery of uranium capacity in re-uses may also vary across different adsorbent formulations. Through multiple re-use the adsorbent AI8 can harvest 10 g uranium/kg adsorbent in ~140 days, using a 28-day adsorption/stripping cycle, a performance much better than would be achieved with a single use of the adsorbent through very long-term exposure (saturation capacity = 7.4 g U/kg adsorbent). A time dependent seawater exposure model to evaluate the cost associated with reusing amidoxime-based adsorbents in real seawater exposures was developed. The cost to extract uranium from seawater ranged from $610-830/kg U was predicted. Model simulation suggests that a short

Stochastic stability of mechanical systems under renewal jump process parametric excitation

DEFF Research Database (Denmark)

Iwankiewicz, R.; Nielsen, Søren R.K.; Larsen, Jesper Winther

2005-01-01

independent, negative exponential distributed variables; hence, the arrival process may be termed as a generalized Erlang renewal process. The excitation process is governed by the stochastic equation driven by two independent Poisson processes, with different parameters. If the response in a single mode...

Copper and zinc removal from roof runoff: from research to full-scale adsorber systems.

Science.gov (United States)

Steiner, M; Boller, M

2006-01-01

Large, uncoated copper and zinc roofs cause environmental problems if their runoff is infiltrated into the underground or discharged into receiving waters. Since source control is not always feasible, barrier systems for efficient copper and zinc removal are recommended in Switzerland. During the last few years, research carried out in order to test the performance of GIH-calcite adsorber filters as a barrier system. Adsorption and mass transport processes were assessed and described in a mathematical model. However, this model is not suitable for practical design, because it does not give explicit access to design parameters such as adsorber diameter and adsorber bed depth. Therefore, for e.g. engineers, an easy to use design guideline for GIH-calcite adsorber systems was developed, mainly based on the mathematical model. The core of this guideline is the design of the depth of the GIH-calcite adsorber layer. The depth is calculated by adding up the GIH depth for sorption equilibrium and the depth for the mass transfer zone (MTZ). Additionally, the arrangement of other adsorber system components such as particle separation and retention volume was considered in the guideline. Investigations of a full-scale adsorber confirm the successful application of this newly developed design guideline for the application of GIH-calcite adsorber systems in practice.

Ni-Ni ion pair excitation transfer in D sub(3h) symmetry

International Nuclear Information System (INIS)

Terrile, M.C.

1990-01-01

The mechanisms contributing to excitation transfer are examined for Ni-Ni ion pairs in order to explain the delocalized character of electronic excitations observed in CsNiF sub(3). Using both first-and second-order perturbation theory and from symmetry arguments, the kind of interactions giving matrix elements between states connecting different sites for the position of the excitation are discussed. (author)

Comparative study of selenite adsorption on carbon based adsorbents and activated alumina.

Science.gov (United States)

Jegadeesan, G; Mondal, K; Lalvani, S B

2003-08-01

The sorption characteristics of carbon-based adsorbents such as activated carbon and chitin for the removal of selenite, Se (IV), an anionic, hazardous contaminant, are compared with those of alpha and gamma alumina. Batch experiments were conducted to determine the influence of pH, concentration of adsorbate, adsorbent loading and temperature on the sorption characteristics of the adsorbents. Generally, low pH of the solution resulted in favorable selenium removal. With the exception of activated carbon, uptakes decreased with increase in temperature. In comparison, chitin was found to be far less effective for the removal of Se (IV) from aqueous solutions. The data also showed that gamma alumina provided higher selenium removal percentages (99%) compared to alpha alumina (94%), activated carbon (87%) and chitin (49%). The selenite removal was found to decrease with increasing initial Se (IV) concentration in the solution. Adsorption capacities of the adsorbents are reported in terms of their Langmuir adsorption isotherms. The adsorption capacity (on unit mass basis) of the adsorbents for selenite is in the order: chitin (specific area (sa) = 9.58 m2 g(-1)) activated carbon (sa = 96.37 m2 g(-1)) < alpha alumina (sa = 6 m2 g(-1)) < gamma alumina (sa = 150 m2 g(-1)).

The recombination channels of luminescence excitation in YAG:Yb single crystalline films

International Nuclear Information System (INIS)

Zakharko, Ya.M.; Luchechko, A.P.; Ubizskii, S.B.; Syvorotka, I.I.; Martynyuk, N.V.; Syvorotka, I.M.

2007-01-01

Absorption and emission spectra, luminescence decay kinetics and thermostimulated luminescence of X-ray irradiated YAG:Yb single crystalline films were studied. Two emission bands peaked at 420 and 488 nm have been detected in the investigated films. The strong thermal quenching of luminescence band at 488 nm was observed above 160 K. The influence of growth conditions and annealing in air on the lifetime of Yb 3+ ion excited state in the IR spectral region have been revealed. The recombination mechanisms of the f-f transition at Yb 3+ ion excitation, as well as the mechanism of lifetime shortening for the excited Yb 3+ luminescence have been discussed

Solid adsorbents for removal of hydrogen sulphide from hot gas

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.; Yumura, Motoo

1986-04-01

A wide range of solids have been tested as potential adsorbents for H/sub 2/S removal from hot gas. These solids can be divided into two main groups, i.e., the adsorbents containing alkaline earth metals and those containing transition metals. Among the former, calcium oxide and naturally occurring materials such as limestone, dolomite and calcium silicate have attracted a great deal of attention. The adsorbents of the second group include iron oxide alone or in combination with some supports, zinc oxide, zinc ferrite and manganese oxide. The materials containing both the alkaline earth metals and transition metals, e.g., manganese nodules, fly ash and the reject from the aluminium industry (red mud) have been evaluated as well.

Citrus paradisi: an effective bio-adsorbent for arsenic (v) remediation

International Nuclear Information System (INIS)

Khaskheli, M.I.; Memon, S.Q.; Parveen, S.

2014-01-01

In the present study As(V) was removed by citrus paradise (grape fruit) peel. Kinetics of the adsorption reaction was analyzed by the Pseudo second order and Morris-weber equations. Freundlich and Langmuir isotherm models were utilized for understanding of the relationship between the arsenic ions and citrus paradise peel adsorbent. The maximum measured uptake capacity of citrus paradise was 37.76 mg.g/sup -1/ at pH 4. FT-IR characterization of unloaded and As (V) loaded citrus paradisi peel adsorbent showed the participation of carbonyl (CO) and hydroxyl (OH) groups in adsorption process. The proposed citrus paradis peel adsorbent with optimized parameters was used for the removal of arsenic from arsenic contaminated real water samples. (author)

Heterogeneous Reactions of Limonene on Mineral Dust: Impacts of Adsorbed Water and Nitric Acid.

Science.gov (United States)

Lederer, Madeline R; Staniec, Allison R; Coates Fuentes, Zoe L; Van Ry, Daryl A; Hinrichs, Ryan Z

2016-12-08

Biogenic volatile organic compounds (BVOCs), including the monoterpene limonene, are a major source of secondary organic aerosol (SOA). While gas-phase oxidation initiates the dominant pathway for BVOC conversion to SOA, recent studies have demonstrated that biogenic hydrocarbons can also directly react with acidic droplets. To investigate whether mineral dust may facilitate similar reactive uptake of biogenic hydrocarbons, we studied the heterogeneous reaction of limonene with mineral substrates using condensed-phase infrared spectroscopy and identified the formation of irreversibly adsorbed organic products. For kaolinite, Arizona Test Dust, and silica at 30% relative humidity, GC-MS identified limonene-1,2-diol as the dominant product with total organic surface concentrations on the order of (3-5) × 10 18 molecules m -2 . Experiments with 18 O-labeled water support a mechanism initiated by oxidation of limonene by surface redox sites forming limonene oxide followed by water addition to the epoxide to form limonenediol. Limonene uptake on α-alumina, γ-alumina, and montmorillonite formed additional products in high yield, including carveol, carvone, limonene oxide, and α-terpineol. To model tropospheric processing of mineral aerosol, we also exposed each mineral substrate to gaseous nitric acid prior to limonene uptake and identified similar surface adsorbed products that were formed at rates 2 to 5 times faster than without nitrate coatings. The initial rate of reaction was linearly dependent on gaseous limonene concentration between 5 × 10 12 and 5 × 10 14 molecules cm -3 (0.22-20.5 ppm) consistent with an Eley-Rideal-type mechanism in which gaseous limonene reacts directly with reactive surface sites. Increasing relative humidity decreased the amount of surface adsorbed products indicating competitive adsorption of surface adsorbed water. Using a laminar flow tube reactor we measured the uptake coefficient for limonene on kaolinite at 25% RH to range from

Electron-impact excitation autoionization of Ga II

International Nuclear Information System (INIS)

Pindzola, M.S.; Griffin, D.C.; Bottcher, C.

1982-01-01

The general-reaction theory of Feshbach is applied, within the framework of the distorted-wave approximation, to the calculation of excitation-autoionization resonances in the electron-impact ionization of Ga + . Although the spectrum of autoionizing levels for Ga + is quite complex, we focus our attention on the important 3d 10 4s 2 → 3d 9 4s 2 4p inner-shell excitations. For excitation of the 3d 9 4s 2 4p 1 P 1 autoionizing level we make a general-reaction-theory calculation for the dominant partial-wave cross section and compute a typical resonance profile in the ejected-electron differential cross section. We find that the quantum-mechanical interference between the direct and indirect processes has a small effect on the total ionization cross section. Employing an independent-processes approximation we calculate excitation-autoionization contributions to all twelve levels of the 3d 9 4s 2 4p configuration. Using the results of our calculations and their comparison with a recent crossed-beam experiment by Rogers et al., we discuss the accuracy of the distorted-wave method and the effects of configuration interaction on energy levels and excitation cross sections

An eco-friendly approach for heavy metal adsorbent regeneration using CO2-responsive molecular octopus.

Science.gov (United States)

Bai, Yu; Liang, Yen Nan; Hu, Xiao

2017-10-01

Perennial problems of adsorption in wastewater treatment include adsorbent recycling, generation of waste sludge and secondary pollution because harmful concentrated acids, bases or strong chelators are often used for adsorbent regeneration and adsorbate recovery. We report, for the first time, an eco-friendly regeneration concept demonstrated with a CO 2 -responsive octopus-like polymeric adsorbent. Various heavy metals can be scavenged at very high Q e by such adsorbent through coordination. Most importantly, the rapid and complete regeneration of the adsorbent and recovery of the heavy metal ions can be readily achieved by CO 2 bubbling within a few minutes under mild conditions, i.e., room temperature and atmospheric pressure. The adsorbent can then be restored to its adsorptive state and reused upon removal of CO 2 by simply bubbling another gas. This eco-friendly, effective, ultra-fast and repeatable CO 2 -triggered regeneration process using CO 2 -responsive adsorbent with versatile structure, morphology or form can be incorporated into a sustainable closed-loop wastewater treatment process to solve the perennial problems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Single stage batch adsorber design for efficient Eosin yellow removalby polyaniline coated ligno-cellulose

CSIR Research Space (South Africa)

Debnath, S

2015-01-01

Full Text Available Polyaniline-coated lignin-based adsorbent (PLC) was synthesized and used for uptake of reactive dye eosin yellow (EY) from aqueous solution. The adsorption capability of the adsorbent was found to be more effective than the unmodified adsorbent (LC...

Starlight excitation of permitted lines in the Orion Nebula

International Nuclear Information System (INIS)

Grandi, S.A.

1975-01-01

From an idealized model of the Orion Nebula and from an analysis of line ratios it is shown that direct starlight excitation of the permitted O I line dominates over recombination and Lyman line fluorescence. The line strengths predicted by this mechanism agree reasonably well with those observed in the Orion Nebula. The application of direct starlight excitation to other ions is also discussed

Learning Enhances Intrinsic Excitability in a Subset of Lateral Amygdala Neurons

Science.gov (United States)

Sehgal, Megha; Ehlers, Vanessa L.; Moyer, James R., Jr.

2014-01-01

Learning-induced modulation of neuronal intrinsic excitability is a metaplasticity mechanism that can impact the acquisition of new memories. Although the amygdala is important for emotional learning and other behaviors, including fear and anxiety, whether learning alters intrinsic excitability within the amygdala has received very little…

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

KAUST Repository

Chakraborty, Anutosh; Saha, Bidyut Baran; Ng, Kim Choon; Koyama, Shigeru; Srinivasan, Kandadai

2009-01-01

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

Lithium. Effects on excitable cell membranes

NARCIS (Netherlands)

Ploeger, Egbert Johan

1974-01-01

LITHIUM: Effects on excitable cell membranes. Lithium salts have been used in the treatment of manic-depressive psychosis for many years but their mechanism of action is not well understood. Many workers assume that the action of lithium on catecholamine metabolism and/or on electrolyte distribution

The synthesis of a new type adsorbent for the removal of toxic gas by radiation-induced graft polymerization

International Nuclear Information System (INIS)

Okamoto, Jiro; Sugo, Takanobu

1990-01-01

A new type of adsorbent containing sulfuric acid group for the removal of ammonia gas was synthesized by radiation-induced graft polymerization of styrene onto fibrous and nonwoven type polypropylene followed by sulufonation with chlorosulfonic acid. The rate of the adsorption of ammonia gas by H-type adsorbent is independent of the ion-exchange capacity. The amount of ammonia gas adsorbed by the chemical adsorption was dependent on the ion-exchange capacity of H-type fibrous adsorbent and was kept constant value in spite of the equilibrium pressure of ammonia gas. Cu(II)- and Ni(II)-types fibrous adsorbent were prepared by the ion exchange reaction of Na-type fibrous adsorbent with metal nitrate solutions. Although, the rate of adsorption of ammonia gas by metal-type fibrous adsorbent is lower than that of H-type adsorbent, the amount of ammonia gas adsorbed increases compared to H-type adsorbent with the same ion exchange capacity. It was related to the highest coordination number of metal ion. The ratio of the number of ammonia molecules adsorbed chemically and the number of metal ion adsorbed in fibrous adsorbent was 4 for Cu-type and 6 for Ni-type fibrous adsorbent, respectively. (author)

Specific binding-adsorbent assay method and test means

International Nuclear Information System (INIS)

1981-01-01

A description is given of an improved specific binding assay method and test means employing a nonspecific adsorbent for the substance to be determined, particularly hepatitis B surface (HBsub(s)) antigen, in its free state or additionally in the form of its immune complex. The invention is illustrated by 1) the radioimmunoadsorbent assay for HBsub(s) antigen, 2) the radioimmunoadsorbent assay for HBsub(s) antigen in the form of immune complex with antibody, 3) a study of adsorption characteristics of various anion exchange materials for HBsub(s) antigen, 4) the use of hydrophobic adsorbents in a radioimmunoadsorbent assay for HBsub(s) antigen and 5) the radioimmunoadsorbent assay for antibody to HBsub(s) antigen. The advantages of the present method for detecting HBsub(s) antigen compared to previous methods include the manufacturing advantages of eliminating the need for insolubilised anti-HBsub(s) and the advantages of a single incubation step, fewer manipulations, storability of adsorbent materials, increased sensitivity and versatility of detecting HBsub(s) antigen in the form of its immune complex if desired. (U.K.)

Production of adsorbent from palm shell for radioactive iodine scrubbing process

International Nuclear Information System (INIS)

Mohamad Azman Che Mat Isa; Ku Halim Ku Hamid; Muhd Noor Muhd Yunus; Mohamad Puad Abu; Abdul Halim Badaruddin; Mohammad Nizammudin Abd Aziz; Muhd Ridwan Abdul Rahim

2010-01-01

The biggest biomass source in Malaysia comes from oil palm industry. According to the statistic of year 2004, Malaysia produced 40 million tones per year of biomass which 30 million tones of biomass originated from the oil palm industries. Therefore, the biomass waste such as palm kernel shell can be used to produce granular adsorbent for radioactive materials. For that reason, a newly system, called Rocking Kiln - Fluidized Bed (RK - FB) was developed to utilize large amount of the biomass to produce high value added product. Charcoal or chemically produced activated carbon could be produced by using the kiln. Washing process was introduced to remove particles, minerals and volatile matters from charcoal produced and then would create more surface area in the adsorbent by creating more active sites. In this research, the adsorbent produced was used to scrub iodine 131. In nuclear power reactor, iodine isotope 131 is produced during nuclear fission, and this elementary radioactive iodine may pollute exhaust air streams that could cause thyroid cancer. For removal of radioactive iodine, normally a potassium iodide - impregnated activated carbon (KI - AC) is used. Thus, a process will be developed to produce KI - AC and this product will be used to calculate the efficiency to remove the radioactive iodine 131.The results obtain show that adsorbent produced has a high potential to be used in radioactive adsorbing and likely more economics. This paper will elaborate further the experimental set-up of in Kiln - Fluidized Bed (RK - FB), adsorbent quality and radioactive scrubbing process. (author)

Laser amplification in excited dielectrics

DEFF Research Database (Denmark)

Winkler, Thomas; Haahr-Lillevang, Lasse; Sarpe, Cristian

2018-01-01

Wide-bandgap dielectrics such as glasses or water are transparent at visible and infrared wavelengths. This changes when they are exposed to ultrashort and highly intense laser pulses. Different interaction mechanisms lead to the appearance of various transient nonlinear optical phenomena. Using...... these, the optical properties of dielectrics can be controlled from the transparent to the metal-like state. Here we expand this range by a yet unexplored mechanism in excited dielectrics: amplification. In a two-colour pump-probe experiment, we show that a 400nm femtosecond laser pulse is coherently...

Screening of natural adsorbents for removal of radio-contaminants from aqueous effluents

International Nuclear Information System (INIS)

Thorat, Vidya; Katarni, V.G.; Kaushik, C.P.; Kaushik, Chander P.; Sharma, J.K.

2010-01-01

The present paper is a summary of studies carried out to examine the uptake potential of some of the bio/natural adsorbents for removal of radiocontaminants from aqueous effluents. Three different bio/natural materials namely coconut coir pith, sugarcane bagasse and saw dust were selected as adsorbents. Preliminary characterisations of the above adsorbents were carried out and percentage of removal of 239 Pu and 241 Am from aqueous solutions were checked using batch equilibration method. (author)

Photoionization dynamics of excited molecular states

International Nuclear Information System (INIS)

Dehmer, J.L.; O'Halloran, M.A.; Tomkins, F.S.; Dehmer, P.M.; Pratt, S.T.

1987-01-01

Resonance Enhanced Multiphoton Ionization (REMPI) utilizes tunable dye lasers to ionize an atom or molecule by first preparing an excited state by multiphoton absorption and then ionizing that state before it can decay. This process is highly selective with respect to both the initial and resonant intermediate states of the target, and it can be extremely sensitive. In addition, the products of the REMPI process can be detected as needed by analyzing the resulting electrons, ions, fluorescence, or by additional REMPI. This points to a number of opportunities for exploring excited state physics and chemistry at the quantum-state-specific level. Here we will first give a brief overview of the large variety of experimental approaches to excited state phenomena made possible by REMPI. Then we will examine in more detail, recent studies of the three photon resonant, four photon (3 + 1) ionization of H 2 via the C 'PI/sup u/ state. Strong non-Franck-Condon behavior in the photoelectron spectra of this nominally simple Rydberg state has led to the examination of a variety of dynamical mechanisms. Of these, the role of doubly excited autoionizing states now seems decisive. Progress on photoelectron studies of autoionizing states in H 2 , excited in a (2 + 1) REMPI process via the E, F 1 Σ/sub g/ + will also be briefly discussed. 26 refs., 7 figs

Effect of adsorbents and chemical treatments on the removal of strontium from aqueous solutions

International Nuclear Information System (INIS)

Ahmadpour, A.; Zabihi, M.; Tahmasbi, M.; Bastami, T. Rohani

2010-01-01

In the present investigation, three different solid wastes namely almond green hull, eggplant hull, and moss were initially treated and used as adsorbents for the adsorption of strontium ion from aqueous solutions. Adsorbent types and chemical treatments are proved to have effective roles on the adsorption of Sr(II) ion. Among the three adsorbents, almond green hull demonstrated strong affinity toward strontium ion in different solutions. The effectiveness of this new adsorbent was studied in batch adsorption mode under a variety of experimental conditions such as: different chemical treatments, various amounts of adsorbent, and initial metal-ion concentration. The optimum doses of adsorbent for the maximum Sr(II) adsorption were found to be 0.2 and 0.3 g for 45 and 102 mg L -1 solutions, respectively. High Sr(II) adsorption efficiencies were achieved only in the first 3 min of adsorbent's contact time. The kinetics of Sr(II) adsorption on almond green hull was also examined and it was observed that it follows the pseudo second-order behavior. Both Langmuir and Freundlich models well predicted the experimental adsorption isotherm data. The maximum adsorption capacity on almond green hull was found to be 116.3 mg g -1 . The present study also confirmed that these low cost agriculture byproducts could be used as efficient adsorbents for the removal of strontium from wastewater streams.

Differential Pair Distribution Function Study of the Structure of Arsenate Adsorbed on Nanocrystalline [gamma]-Alumina

Energy Technology Data Exchange (ETDEWEB)

Li, Wei; Harrington, Richard; Tang, Yuanzhi; Kubicki, James D.; Aryanpour, Masoud; Reeder, Richard J.; Parise, John B.; Phillips, Brian L. (SBU); (Penn)

2012-03-15

Structural information is important for understanding surface adsorption mechanisms of contaminants on metal (hydr)oxides. In this work, a novel technique was employed to study the interfacial structure of arsenate oxyanions adsorbed on {gamma}-alumina nanoparticles, namely, differential pair distribution function (d-PDF) analysis of synchrotron X-ray total scattering. The d-PDF is the difference of properly normalized PDFs obtained for samples with and without arsenate adsorbed, otherwise identically prepared. The real space pattern contains information on atomic pair correlations between adsorbed arsenate and the atoms on {gamma}-alumina surface (Al, O, etc.). PDF results on the arsenate adsorption sample on {gamma}-alumina prepared at 1 mM As concentration and pH 5 revealed two peaks at 1.66 {angstrom} and 3.09 {angstrom}, corresponding to As-O and As-Al atomic pair correlations. This observation is consistent with those measured by extended X-ray absorption fine structure (EXAFS) spectroscopy, which suggests a first shell of As-O at 1.69 {+-} 0.01 {angstrom} with a coordination number of 4 and a second shell of As-Al at 3.13 {+-} 0.04 {angstrom} with a coordination number of 2. These results are in agreement with a bidentate binuclear coordination environment to the octahedral Al of {gamma}-alumina as predicted by density functional theory (DFT) calculation.

Differential pair distribution function study of the structure of arsenate adsorbed on nanocrystalline γ-alumina.

Science.gov (United States)

Li, Wei; Harrington, Richard; Tang, Yuanzhi; Kubicki, James D; Aryanpour, Masoud; Reeder, Richard J; Parise, John B; Phillips, Brian L

2011-11-15

Structural information is important for understanding surface adsorption mechanisms of contaminants on metal (hydr)oxides. In this work, a novel technique was employed to study the interfacial structure of arsenate oxyanions adsorbed on γ-alumina nanoparticles, namely, differential pair distribution function (d-PDF) analysis of synchrotron X-ray total scattering. The d-PDF is the difference of properly normalized PDFs obtained for samples with and without arsenate adsorbed, otherwise identically prepared. The real space pattern contains information on atomic pair correlations between adsorbed arsenate and the atoms on γ-alumina surface (Al, O, etc.). PDF results on the arsenate adsorption sample on γ-alumina prepared at 1 mM As concentration and pH 5 revealed two peaks at 1.66 Å and 3.09 Å, corresponding to As-O and As-Al atomic pair correlations. This observation is consistent with those measured by extended X-ray absorption fine structure (EXAFS) spectroscopy, which suggests a first shell of As-O at 1.69 ± 0.01 Å with a coordination number of ~4 and a second shell of As-Al at ~3.13 ± 0.04 Å with a coordination number of ~2. These results are in agreement with a bidentate binuclear coordination environment to the octahedral Al of γ-alumina as predicted by density functional theory (DFT) calculation.

Cauliflower-like CuI nanostructures: Green synthesis and applications as catalyst and adsorbent

Energy Technology Data Exchange (ETDEWEB)

Jiang Yi [College of Chemistry and Environmental Science, Henan Normal University, Xinxiang, Henan 453007 (China); Gao Shuyan, E-mail: shuyangao@htu.cn [College of Chemistry and Environmental Science, Henan Normal University, Xinxiang, Henan 453007 (China); Li Zhengdao; Jia Xiaoxia; Chen Yanli [College of Chemistry and Environmental Science, Henan Normal University, Xinxiang, Henan 453007 (China)

2011-08-15

Highlights: > In this study we report a green, environment-friendly, efficient, and direct one-step process for the preparation of CuI cauliflower. > The as-formed CuI cauliflower shows excellent catalytic activity for coupling reaction between benzylamine and iodobenzene. > The cauliflower-like CuI nanostructures have been successfully demonstrated as adsorbent for Cd (II) with high removal capacity. > To the best of our knowledge, it is the first report that nanostructured CuI acts as catalyst for coupling reaction and adsorbent for heavy metal ion. > It is also a good example for the organic combination of green chemistry and functional materials. - Abstract: Cauliflower-like CuI nanostructures is realized by an ampicillin-assisted clean, nontoxic, environmentally friendly synthesis strategy at room temperature. The morphology, composition, and phase structure of as-prepared powders were characterized by field emission scanning electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. The results show that ampicillin plays dual roles, reducing and morphology-directing agents, in the formation of the products. A possible growth mechanism of the cauliflower-like CuI nanostructures is tentatively proposed. The preliminary investigations show that the cauliflower-like CuI structure not only exhibits high catalytic activity with respect to coupling reaction between benzylamine and iodobenzene but also possesses high removal capacity for Cd (II), which may be ascribed to the high specific surface area of the special configuration. To the best of our knowledge, it is the first report that cauliflower-like CuI nanoparticles act as catalyst for coupling reaction and adsorbent for heavy metal ion.

Application of the Real-Time Time-Dependent Density Functional Theory to Excited-State Dynamics of Molecules and 2D Materials

Science.gov (United States)

Miyamoto, Yoshiyuki; Rubio, Angel

2018-04-01

We review our recent developments in the ab initio simulation of excited-state dynamics within the framework of time-dependent density functional theory (TDDFT). Our targets range from molecules to 2D materials, although the methods are general and can be applied to any other finite and periodic systems. We discuss examples of excited-state dynamics obtained by real-time TDDFT coupled with molecular dynamics (MD) and the Ehrenfest approximation, including photoisomerization in molecules, photoenhancement of the weak interatomic attraction of noble gas atoms, photoenhancement of the weak interlayer interaction of 2D materials, pulse-laser-induced local bond breaking of adsorbed atoms on 2D sheets, modulation of UV light intensity by graphene nanoribbons at terahertz frequencies, and collision of high-speed ions with the 2D material to simulate the images taken by He ion microscopy. We illustrate how the real-time TDDFT approach is useful for predicting and understanding non-equilibrium dynamics in condensed matter. We also discuss recent developments that address the excited-state dynamics of systems out of equilibrium and future challenges in this fascinating field of research.

The synthesis of corncobs (zea mays) active charcoal and water hyacinth (eichornia crassipes) adsorbent to adsorb Pb(II) with it’s analysis using solid-phase spectrophotometry (sps)

Science.gov (United States)

Saputro, S.; Masykuri, M.; Mahardiani, L.; Kurniastuti, D.

2018-03-01

This research aim to examine the effect of the combination between corncobs and water hyacinth to adsorb lead (II), the most effective combination have determined by compared the ratio of corncobs adsorbent and water hyacinth to the increasing adsorption of the Pb(II), prove the effectiveness of the solid-phase spectrophotometry (sps) to determine the levels of Pb(II) as the result of the corncobs active charcoal adsorption and water hyacinth in the level of µg/L. The research method used is experimental method. The data collecting technique is carried out by several stages, which are carbonization using muffle furnace at a temperature of 350°C for 1.5 hours, activation of the corncobs charcoal and water hyacinth using HCl 1M and HCl 5M activator, contacting the adsorbent of corncobs active charcoal and water hyacinth with liquid waste simulation of Pb(II) using variation of corncobns and water hyacinth, 1:0; 0:1; 1:1; 2:1; 1:2, analysis of Pb(II) using an sps, characterization of corncobs active charcoal adsorbent and water hyacinth using FTIR. Research results show that the combined effect of activated charcoal corncobs and water hyacinth can increase the ability of the adsorbent to absorb Pb(II), the optimum adsorbent mass ratio of 1:1 with the absorption level of 90.33%, SPS is an effective method to analyze the decreasing level of Pb(II) as the adsorbtion result of the corncobs active charcoal and water hyacinth in the level of µg/L, with the limit of detection (LOD) of 0.06 µg/L.

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.

Enhanced eumelanin emission by stepwise three-photon excitation

Science.gov (United States)

Kerimo, Josef; Rajadhyaksha, Milind; DiMarzio, Charles A.

2011-03-01

Eumelanin fluorescence from Sepia officinalis and black human hair was activated with near-infrared radiation and multiphoton excitation. A third order multiphoton absorption by a step-wise process appears to be the underlying mechanism. The activation was caused by a photochemical process since it could not be reproduced by simple heating. Both fluorescence and brightfield imaging indicate the near-infrared irradiation caused photodamage to the eumelanin and the activated emission originated from the photodamaged region. At least two different components with about thousand-fold enhanced fluorescence were activated and could be distinguished by their excitation properties. One component was excited with wavelengths in the visible region and exhibited linear absorption dependence. The second component could be excited with near-infrared wavelengths and had a third order dependence on the laser power. The third order dependence is explained by a step-wise excited state absorption (ESA) process since it could be observed equally with the CW and femtosecond lasers. The new method for photoactivating the eumelanin fluorescence was used to map the melanin content in human hair.

Citrus paradisi: An Effective bio-adsorbent for Arsenic (V Remediation

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Mazhar I. Khaskheli

2014-06-01

Full Text Available In the present study As (V was removed by citrus paradisi (grape fruit peel. Kinetics of the adsorption reaction was analyzed by the Pseudo second order and Morris-weber equations. Freundlich and Langmuir isotherm models were utilized for understanding of the relationship between the arsenic ions and citrus paradisi peel adsorbent. The maximum measured uptake capacity of citrus paradisi was 37.76 mg.g-1 at pH 4. FT-IR characterization of unloaded and As (V loaded citrus paradisi peel adsorbent showed the participation of carbonyl (CO and hydroxyl (OH groups in adsorption process. The proposed citrus paradisi peel adsorbent with optimized parameters was used for the removal of arsenic from arsenic contaminated real water samples.

Metal Adsorbent Prepared from Poly(Methyl Acrylate)-Grafted Cassava Starch via Gamma Irradiation

Energy Technology Data Exchange (ETDEWEB)

Suwanmala, P; Hemvichian, K; Srinuttrakul, W [Nuclear Research and Development Group, Thailand Institute of Nuclear Technology, Bangkok (Thailand)

2012-09-15

Metal adsorbent containing hydroxamic acid groups was successfully synthesized by radiation-induced graft copolymerization of methyl acrylate (MA) onto cassava starch. The optimum conditions for grafting were studied in terms of % degree of grafting (Dg). Conversion of the ester groups present in poly(methyl acrylate)-grafted-cassava starch copolymer into hydroxamic acid was carried out by treatment with hydroxylamine (HA) in the presence of alkaline solution. The maximum percentage conversion of the ester groups of the grafted copolymer, %Dg = 191 (7.63 mmol/g of MA), into the hydroxamic groups was 70% (5.35 mmol/g of MA) at the optimum conditions: in a mixture solution of 20% HA (w/v) and methanol solution (methanol:H{sub 2}O = 5:1) 300 mL, pH 13, reaction time 2 h, and 20 g of grafted copolymer. The adsorbent was characterized by FTIR, TGA, and DSC. The presence of electron donating groups in adsorbent containing hydroxamic acid groups gives the ability to form polycomplexes with metal ions. The ability of the adsorbent to adsorb various metals was investigated in order to evaluate the possibility of its use in metal adsorption. The adsorbent exhibited a remarkable % adsorption for Cd{sup 2+}, Al{sup 3+}, UO{sub 2} {sup 2+}, V{sup 5+} and Pb{sup 2+} at pH 3, 4, 5, 4, and 3, respectively. The adsorbent of 191%Dg had total adsorption capacities of 2.6, 1.46, 1.36, 1.15, and 1.6 mmol/g adsorbent for Cd{sup 2+}, Al{sup 3+}, UO{sub 2} {sup 2+}, V{sup 5+} and Pb{sup 2+}, respectively, in the batch mode adsorption. (author)

High performance of a unique mesoporous polystyrene-based adsorbent for blood purification.

Science.gov (United States)

Chen, Jian; Han, Wenyan; Chen, Jie; Zong, Wenhui; Wang, Weichao; Wang, Yue; Cheng, Guanghui; Li, Chunran; Ou, Lailiang; Yu, Yaoting

2017-02-01

A multi-functional polystyrene based adsorbent (NKU-9) with a unique mesoporous and a high surface area was prepared by suspension polymerization for removal of therapeutic toxins in blood purification. The adsorbent produced had an almost equal amount of mesopore distribution in the range from 2 to 50 nm. The adsorption of serum toxins with different molecular weights were examined by in vitro adsorption assays and compared with some clinical currently used adsorbents such as HA-330, Cytosorb and BL-300 which are produced by China, America and Japan, respectively. Test results indicated that the adsorption rate for pentobarbital by NKU-9 was 81.24% which is nearly as high as HA-330 (81.44%). The latter adsorbent is currently used for acute detoxification treatment in China. To reach adsorption equilibrium, NKU-9 was faster than HA-330, which implies short treatment time. For the removal of middle molecular toxins such as β2-microglobulin (98.88%), NKU-9 performed better adsorptive selectivity than Cytosorb (92.80%). In addition, NKU-9 showed high performance for the removal of albumin-bound toxins (e.g., bilirubin), and its adsorption rate for total bilirubin (80.79%) in plasma was 8.4% higher than that of anion exchange resin BL-300 which is currently used to eliminate bilirubin in clinic. Therefore, our results indicate that the newly developed adsorbent with a wide distribution and almost equal amount of mesopores is a multifunctional adsorbent for high efficient removal of serum toxins with different molecular weights which might be an excellent blood purification adsorbent especially to treat diseases that conventional medical methods are low or not efficient.

Adsorption of Cr(VI) using silica-based adsorbent prepared by radiation-induced grafting

International Nuclear Information System (INIS)

Qiu Jingyi; Wang Ziyue; Li Huibo; Xu Ling; Peng Jing; Zhai Maolin; Yang Chao; Li Jiuqiang; Wei Genshuan

2009-01-01

Silica-based adsorbent was prepared by radiation-induced grafting of dimethylaminoethyl methacrylate (DMAEMA) onto the silanized silica followed by a protonation process. The FTIR spectra and XPS analysis proved that DMAEMA was grafted successfully onto the silica surface. The resultant adsorbent manifested a high ion exchange capacity (IEC) of ca. 1.30 mmol/g and the Cr(VI) adsorption behavior of the adsorbent was further investigated, revealing the recovery of Cr(VI) increased with the adsorbent feed and the equilibrium adsorption could be achieved within 40 min. The adsorption capacity, strongly depended on the pH of the solution, reached a maximum Cr(VI) uptake (ca. 68 mg/g) as the pH was in the range of 2.5-5.0. Furthermore, even in strong acidic (4.0 mol/L HNO 3 ) or alkaline media (pH 11.0), the adsorbent had a sound Cr(VI) uptake capacity (ca. 22 and 30 mg/g, respectively), and the adsorption followed Langmuir mode. The results indicated that this adsorbent, prepared via a convenient approach, is applicable for removing heavy-metal-ion pollutants (e.g. Cr(VI)) from waste waters.

Formation and role of excited states in radiolysis - a foreword

International Nuclear Information System (INIS)

Singh, A.

1976-01-01

It is stated that the choice of contributions to the special issue of this Journal has been limited to those which bear on the details of the mechanisms of excited state formation and are likely to be useful to radiation chemists. Since more than half the energy deposited in radiolysis goes into excitation, studies on the fate of the excited species formed are very important. A brief reference is made to the subject matter of each of the fifteen contributions, and its significance to the development of the technique of radiolysis is outlined. (U.K.)

New adsorbents from oil shales. Preparation, characterization and U, Th isotope adsorption tests

International Nuclear Information System (INIS)

Khouya, E.; Andres, Y.; Naslain, R.; Pailler, R.; Nourredine, A.

2004-01-01

New activated adsorbents for radionuclides have been produced from Moroccan oil shales by pyrolysis of the natural material at 550 deg C flowed by a KMnO 4 activation. The texture and composition of the native rock and the adsorbents were studied before their use in tests for adsorption of radionuclides from standard solutions prepared from uranylnitrate and thorium nitrate in equilibrium with their daughters. The distribution coefficients between solutions containing U, Th and Ra and the adsorbents were evaluated by means of specific activities, measured by γ-ray spectrometry. The adsorbents were observed to eliminate U, Th, Ra, Ac and Tl from aqueous solutions. (author)

Terahertz Solitons in Biomolecular Systems and their Excitation by External Electromagnetic Field

Directory of Open Access Journals (Sweden)

Bugay А.N.

2015-01-01

Full Text Available Nonlinear dynamics of charge and acoustic excitations in cellular microtubules is considered. Different types of nonlinear solitary waves were studied taking account for dissipation. The mechanism of electro-acoustic pulse excitation by external electromagnetic field of terahertz frequency is recognized.

The EMP excitation of radiation by the pulsed relativistic electron beam

International Nuclear Information System (INIS)

Balakirev, V.A.; Sidelnikov, G.L.

1996-01-01

The mechanisms of excitation of ultra-wideband electromagnetic pulses (EMP) by short pulses of high-current relativistic electron beams were proposed and investigated. It is shown that the transformation efficiency of the bunch kinetic energy to the excited energy of the EMP can be very significant. (author). 2 figs., 4 refs

The EMP excitation of radiation by the pulsed relativistic electron beam

Energy Technology Data Exchange (ETDEWEB)

Balakirev, V A; Sidelnikov, G L [Kharkov Inst. of Physics and Technology (Russian Federation)

1997-12-31

The mechanisms of excitation of ultra-wideband electromagnetic pulses (EMP) by short pulses of high-current relativistic electron beams were proposed and investigated. It is shown that the transformation efficiency of the bunch kinetic energy to the excited energy of the EMP can be very significant. (author). 2 figs., 4 refs.

Vibrational dynamics of adsorbed molecules under conditions of photodesorption: Pump-probe SFG spectra of CO/Pt(111)

Science.gov (United States)

Fournier, Frédéric; Zheng, Wanquan; Carrez, Serge; Dubost, Henri; Bourguignon, Bernard

2004-09-01

Interaction of CO adsorbed on Pt(111) with electrons and phonons is studied experimentally by means of a pump-probe experiment where CO is probed by IR+visible sum frequency generation under a pump laser intensity that allows photodesorption. Vibrational spectra of CO internal stretch are obtained as a function of pump-probe delay. A two-temperature and anharmonic coupling model is used to extract from the spectra the real time variations of CO peak frequency and dephasing time. The main conclusions are the following: (i) The CO stretch is perturbed by two low-frequency modes, assigned to frustrated rotation and frustrated translation. (ii) The frustrated rotation is directly coupled to electrons photoexcited in Pt(111) by the pump laser. (iii) There is no evidence of Pt-CO stretch excitation in the spectra. The implications for the photodesorption dynamics are discussed.

Poorly crystalline hydroxyapatite: A novel adsorbent for enhanced fulvic acid removal from aqueous solution

Science.gov (United States)

Wei, Wei; Yang, Lei; Zhong, Wenhui; Cui, Jing; Wei, Zhenggui

2015-03-01

In this study, poorly crystalline hydroxyapatite (HAP) was developed as an efficient adsorbent for the removal of fulvic acid (FA) from aqueous solution. Surface functionality, crystallinity, and morphology of the synthetic adsorbent were studied by Fourier-transformation infrared (FT-IR) spectroscopy, powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of various parameters such as crystallinity of adsorbent, contact time, adsorbent dosage, pH, initial adsorbate concentration, temperature, ionic strength and the presence of alkaline earth metal ions on FA adsorption were investigated. Results indicated that the nanosized HAP calcined at lower temperature was poorly crystalline (Xc = 0.23) and had better adsorption capacity for FA than those (Xc = 0.52, 0.86) calcined at higher temperature. FA removal was increased with increases of adsorbent dosage, temperature, ionic strength and the presence of alkali earth metal ions, but decreased as the pH increased. Kinetic studies showed that pseudo-second-order kinetic model better described the adsorption process. Equilibrium data were best described by Sips models, and the estimated maximum adsorption capacity of poorly crystalline HAP was 90.20 mg/g at 318 K, displaying higher efficiency for FA removal than previously reported adsorbents. FT-IR results revealed that FA adsorption over the adsorbent could be attributed to the surface complexation between the oxygen atom of functional groups of FA and calcium ions of HAP. Regeneration studies indicated that HAP could be recyclable for a long term. Findings of the present work highlight the potential for using poorly crystalline HAP nanoparticles as an effective and recyclable adsorbent for FA removal from aqueous solution.

Adaptive transition rates in excitable membranes

Directory of Open Access Journals (Sweden)

Shimon Marom

2009-02-01

Full Text Available Adaptation of activity in excitable membranes occurs over a wide range of timescales. Standard computational approaches handle this wide temporal range in terms of multiple states and related reaction rates emanating from the complexity of ionic channels. The study described here takes a different (perhaps complementary approach, by interpreting ion channel kinetics in terms of population dynamics. I show that adaptation in excitable membranes is reducible to a simple Logistic-like equation in which the essential non-linearity is replaced by a feedback loop between the history of activation and an adaptive transition rate that is sensitive to a single dimension of the space of inactive states. This physiologically measurable dimension contributes to the stability of the system and serves as a powerful modulator of input-output relations that depends on the patterns of prior activity; an intrinsic scale free mechanism for cellular adaptation that emerges from the microscopic biophysical properties of ion channels of excitable membranes.

Graft copolymerization of polystyrene onto chitosan congress as an adsorbent for the removal of heavy metal ions

International Nuclear Information System (INIS)

Dela Mines, Remedel D.; Muncal, Danilet Vi A.

2013-01-01

Chitosan is primarily composed of glucosamine, 2-amino-2-deoxy-β-D-glucose. Chitosan has different types of reactive functional groups. Both hydroxyl and amino groups are possible sites for the reaction to incorporate new and desired functional groups. By modification of these groups various materials for different field of application can be achieved. Chitosan has been used as adsorbent for the removal of heavy metal ions from aqueous solution through adsorption process. Properties of chitosan, such as solubility, mechanical stability and adsorption compatibility, are enhanced by grafting. In this study, chitosan was graft copolymerized with polystyrene for wastewater treatment and evaluated its effectiveness in removing toxic heavy metals by adsorption. Chitosan-graft-polystyrene was characterized by FTIR spectroscopy, and SEM. Adsorption study of the copolymer is carried out as a function of adsorbent dose, pH, and contact time. Residual concentration was measured by Atomic Absorption Spectroscopy. To get an insight of the rate of adsorption and the rate limiting step of the transport mechanism, kinetic analysis was utilized. Langmuir equation/isotherm was used for proper quantification of the sorption equilibrium in the bio sorption process (author)

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

International Nuclear Information System (INIS)

Goncalves, M.R.; Marti, O.; Fabian Enderle, F.

2012-01-01

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. excitation: by far-field illumination of metal nanostructures or rough metal Raman scattering cross-section of gold-palladium target Temporal Fluctuation in SERS Temporal and spectral fluctuations.

Coulomb excitation

International Nuclear Information System (INIS)

McGowan, F.K.; Stelson, P.H.

1974-01-01

The theory of Coulomb excitation and a brief review of pertinent treatments of the Coulomb excitation process that are useful for the analysis of experiments are given. Examples demonstrating the scope of nuclear structure information obtainable from gamma spectroscopy are presented. Direct Elambda excitation of 232 Th is discussed in terms of the one phonon octupole vibrational spectrum. B(MI) reduced transition probabilities resulting from Coulomb excitation of odd-A deformed nuclei with heavy ions are presented as a test of the rotational model. The use of gamma ray coincidence and particle-gamma coincidence as tools for investigating Coulomb excitation is discussed. (U.S.)

Adjuvant effects of aluminium hydroxide-adsorbed allergens and allergoids – differences in vivo and in vitro

Science.gov (United States)

Heydenreich, B; Bellinghausen, I; Lund, L; Henmar, H; Lund, G; Adler Würtzen, P; Saloga, J

2014-01-01

Allergen-specific immunotherapy (SIT) is a clinically effective therapy for immunoglobulin (Ig)E-mediated allergic diseases. To reduce the risk of IgE-mediated side effects, chemically modified allergoids have been introduced. Furthermore, adsorbance of allergens to aluminium hydroxide (alum) is widely used to enhance the immune response. The mechanisms behind the adjuvant effect of alum are still not completely understood. In the present study we analysed the effects of alum-adsorbed allergens and allergoids on their immunogenicity in vitro and in vivo and their ability to activate basophils of allergic donors. Human monocyte derived dendritic cells (DC) were incubated with native Phleum pratense or Betula verrucosa allergen extract or formaldehyde-or glutaraldehyde-modified allergoids, adsorbed or unadsorbed to alum. After maturation, DC were co-cultivated with autologous CD4+ T cells. Allergenicity was tested by leukotriene and histamine release of human basophils. Finally, in-vivo immunogenicity was analysed by IgG production of immunized mice. T cell proliferation as well as interleukin (IL)-4, IL-13, IL-10 and interferon (IFN)-γ production were strongly decreased using glutaraldehyde-modified allergoids, but did not differ between alum-adsorbed allergens or allergoids and the corresponding unadsorbed preparations. Glutaraldehyde modification also led to a decreased leukotriene and histamine release compared to native allergens, being further decreased by adsorption to alum. In vivo, immunogenicity was reduced for allergoids which could be partly restored by adsorption to alum. Our results suggest that adsorption of native allergens or modified allergoids to alum had no consistent adjuvant effect but led to a reduced allergenicity in vitro, while we observed an adjuvant effect regarding IgG production in vivo. PMID:24528247

Kinetics of Cd2+ and Cr3+ Sorption from Aqueous Solutions Using Mercaptoacetic Acid Modified and Unmodified Oil Palm Fruit Fibre(Elaeis guineensis) Adsorbents

Institute of Scientific and Technical Information of China (English)

无

2007-01-01

The kinetics of the sorption of Cd2+ and Cr3+ from aqueous solutions by mercaptoacetic acid modified and unmodified oil palm fruit fibre adsorbents were investigated. The results indicate that sorption equilibrium was reached within 60 min for both metals. Also, the removal efficiency of the three adsorbents was observed to increase for both metals with stronger treatments with mercaptoacetic acid. This may be attributed to the influence of the thiolation of the adsorbents. Furthermore, Cr3+ had higher removal percentages than Cd2+ for all the adsorbents. The sorption mechanism based on the intraparticle diffusion model shows that Cd2+ sorption is better described than Cr3+. The intraparticle diffusion rate constants, K1d, for Cd2+are 62.04 min-1 (untreated), 67.01 min-1 (treated with 0.5 mol/L mercaptoacetic acid), and 71.43 min-1(treated with 1.0 mol/L mercaptocacetic acid) while those for Cr3+ are 63.41 min-1 (untreated), 65.79 min-1(0.5 mol/L acid treated), and 66.25 min-1 (1.0 mol/L acid treated).

Fibroblast proliferation alters cardiac excitation conduction and contraction: a computational study*

Science.gov (United States)

Zhan, He-qing; Xia, Ling; Shou, Guo-fa; Zang, Yun-liang; Liu, Feng; Crozier, Stuart

2014-01-01

In this study, the effects of cardiac fibroblast proliferation on cardiac electric excitation conduction and mechanical contraction were investigated using a proposed integrated myocardial-fibroblastic electromechanical model. At the cellular level, models of the human ventricular myocyte and fibroblast were modified to incorporate a model of cardiac mechanical contraction and cooperativity mechanisms. Cellular electromechanical coupling was realized with a calcium buffer. At the tissue level, electrical excitation conduction was coupled to an elastic mechanics model in which the finite difference method (FDM) was used to solve electrical excitation equations, and the finite element method (FEM) was used to solve mechanics equations. The electromechanical properties of the proposed integrated model were investigated in one or two dimensions under normal and ischemic pathological conditions. Fibroblast proliferation slowed wave propagation, induced a conduction block, decreased strains in the fibroblast proliferous tissue, and increased dispersions in depolarization, repolarization, and action potential duration (APD). It also distorted the wave-front, leading to the initiation and maintenance of re-entry, and resulted in a sustained contraction in the proliferous areas. This study demonstrated the important role that fibroblast proliferation plays in modulating cardiac electromechanical behaviour and which should be considered in planning future heart-modeling studies. PMID:24599687

Enhancement of deposition rate at cryogenic temperature in synchrotron radiation excited deposition of silicon film

International Nuclear Information System (INIS)

Nara, Yasuo; Sugita, Yoshihiro; Ito, Takashi; Kato, Hiroo; Tanaka, Ken-ichiro

1989-01-01

The authors have investigated the synchrotron radiation excited deposition of silicon films on the SiO 2 substrate by using SiH 4 /He mixture gas at BL-12C at Photon Factory. They used VUV light from the multilayer mirror with the center photon energy from 97 to 123eV, which effectively excites L-core electrons of silicon. Substrate temperature was widely varied from -178 degree C to 500 degree C. At -178 degree C, the deposition rate was as high as 400nm/200mAHr (normalized at the storage ring current at 200mA). As increasing the substrate temperature, the deposition rate was drastically decreased. The number of deposited silicon atoms is estimated to be 4 to 50% of incident photons, while the number of photo generated species in the gas phase within the mean free path from the surface is calculated as few as about 10 -3 of incident photons. These experimental results show that the deposition reaction is governed by the dissociation of surface adsorbates by the synchrotron radiation

Experimental Evaluation Use of Semifluidized Bed Adsorber for the Treatment of P-chlorophenol and O-cresol in Wastewater using Activated Carbon as Adsorbent

Directory of Open Access Journals (Sweden)

Saad Hanash Ammar

2015-12-01

Full Text Available In the present work the performance of semifluidized bed adsorber was evaluated for removal of phenolic compound from wastewater using commercial activated carbon as adsorbent. P-chlorophenol (4-Chlorophenol and o-cresol (2-methylphenol was selected as a phenolic compound for that purpose. The phenols percent removal, in term of breakthrough curves were studied as affected by hydrodynamics limitations which include minimum and maximum semifluidization velocities and packed bed formation in the column by varying various parameters such as inlet liquid superficial velocity (from Uminsf to 8Uminsf m/s, and retaining grid (sometimes referred to as adsorbent loading to initial static bed height ratio (from 3-4.5. Inlet phenols concentration (50-400 mg/l and initial pH of the liquid solutions feed (from 4 to 10 were also studied. The experimental semifluidized adsorber unit was designed and constructed in Chem. Eng. labs at Al-Nahrain University (consisted of a QVF glass tube 2.54 cm inside diameter, and 70cm length. The results showed that the initial percent removal of phenolic compounds (P-chlorophenol and o-cresol decrease with increasing the superficial liquid velocity while the time required reaching equilibrium state decreased. Also it slightly affected with the increase in the retaining grid height and the time required to reach the equilibrium value decreased.

Vanadium (4) complexing in phase of adsorbent with benzimidazole groups

International Nuclear Information System (INIS)

Shvoeva, O.P.; Kuchava, G.P.; Evtikova, G.A.; Belyaeva, V.K.; Myasoedova, G.V.; Marov, I.N.

1989-01-01

Equilibrium and kinetic characteristics of V 4+ sorption by POLYORGS XI-H adsorbent with benzimidazole groups (BIm) are investigated. Using ESR method it is stated that [VO 2+ ]:[BIm]1:2 complex, where VO 2+ is combined with nitrogen atoms of two imidazole groups, is formed in adsorbent phase. The highest distribution factor of 4.7x10 3 is attained at pH6

Stochastic Description of Activated Surface Diffusion with Interacting Adsorbates

Science.gov (United States)

Martínez-Casado, Ruth; Vega, José Luis; Sanz, Ángel S.; Miret-Artés, Salvador

Activated surface diffusion on metal surfaces is receiving much attention both experimentally and theoretically. One of the main theoretical problems in this field is to explain the line-shape broadening observed when the surface coverage is increased. Recently, we have proposed a fully stochastic model, the interacting single adsorbate (ISA) model, aimed at explaining and understanding this type of experiments, which essentially consists of considering the classical Langevin formulation with two types of noise forces: (i) a Gaussian white noise accounting for the substrate friction, and (ii) a shot noise simulating the interacting adsorbates at different coverages. No interaction potential between adsorbates is included because any trace of microscopic interaction seems to be wiped out in a Markovian regime. This model describes in a good approximation, and at a very low computational cost, the line-shape broadening observed experimentally. Furthermore, its mathematical simplicity also allows to derive some analytical expressions which are of much help in the interpretation of the physics underlying surface diffusion processes.

Numerical study of friction of flake and adsorbed monolayer on atomically clean substrate

International Nuclear Information System (INIS)

Matsukawa, Hiroshi; Haraguchi, Kazuhiro; Ozaki, Shinsuke

2007-01-01

Frictional behaviors of flake and adsorbed monolayer on substrate can be observed by Frictional force microscope and Quartz crystal microbalance experiments and are typical problems in nano-friction. Computer simulations had been played important roles in understanding those behaviors, but in most of them the driving direction coincides with one of the crystal axes of the substrate. Here we report our numerical results of direction dependence of friction of flake and adsorbed monolayer. We found a new kind of dynamical phase transition in which flake and adsorbed monlayer change their structure relative to the substrate and make incommensurae structure to reduce kinetic frictional force after certain transition time. When the driving velocity is decreased the transition time tends to diverge at certain critical velocity for the flake. For the adsorbed monlayer the transition time tends to diverge at certain critical magnitudes of the external force or the interaction strength between adsorbates when they are decreased

Resonance of magnetization excited by voltage in magnetoelectric heterostructures

Science.gov (United States)

Yu, Guoliang; Zhang, Huaiwu; Li, Yuanxun; Li, Jie; Zhang, Dainan; Sun, Nian

2018-04-01

Manipulation of magnetization dynamics is critical for spin-based devices. Voltage driven magnetization resonance is promising for realizing low-power information processing systems. Here, we show through Finite Element Method (FEM) simulations that magnetization resonance in nanoscale magnetic elements can be generated by a radio frequency (rf) voltage via the converse magnetoelectric (ME) effect. The magnetization dynamics induced by voltage in a ME heterostructures is simulated by taking into account the magnetoelastic and piezoelectric coupling mechanisms among magnetization, strain and voltage. The frequency of the excited magnetization resonance is equal to the driving rf voltage frequency. The proposed voltage driven magnetization resonance excitation mechanism opens a way toward energy-efficient spin based device applications.

Robust structural design against self-excited vibrations

CERN Document Server

Spelsberg-Korspeter, Gottfried

2013-01-01

This book studies methods for a robust design of rotors against self-excited vibrations. The occurrence of self-excited vibrations in engineering applications if often unwanted and in many cases difficult to model. Thinking of complex systems such as machines with many components and mechanical contacts, it is important to have guidelines for design so that the functionality is robust against small imperfections. This book discusses the question on how to design a structure such that unwanted self-excited vibrations do not occur. It shows theoretically and practically that the old design rule to avoid multiple eigenvalues points toward the right direction and have optimized structures accordingly. This extends results for the well-known flutter problem in which equations of motion with constant coefficients occur to the case of a linear conservative system with arbitrary time periodic perturbations.

Quantitative relationship between adsorbed amount of solute and solvent composition

International Nuclear Information System (INIS)

Wang Yan; Geng Xindu; Zebolsky, Don M.

2003-01-01

A new adsorption isotherm that relates the amount of solute adsorbed to the solvent concentration is proposed. The new equation is derived from Geng and Shi's stoichiometric displacement model for adsorption (SDM-A). The obtained equation may be simplified to an expression containing two parameters. The equation with two parameters, valid for low concentrations of solute, is a logarithmically linear relationship. The intercept contains a thermodynamic equilibrium constant of the solute displacing solvent from the adsorbent. The slope is the negative value of the stoichiometric displacement parameter (Z), the average total number of solvent molecules displaced from an active site on the adsorbent and from the solute. Tests with a homologous series of aromatic alcohols by frontal analysis in reversed phase liquid chromatography demonstrate that experimental results fit the equation well

Advanced honeycomb adsorbent and scaling-up technique for thermal swing adsorptive VOC concentrator; Samarusuingu kyuchakushiki VOC noshuku sochiyo hanikamu kyuchakutai no kaizen to sukeru up gijutsu ni tsuite

Energy Technology Data Exchange (ETDEWEB)

Mitsuma, Y.; Kuwa, T.; Yamauchi, H. [Seibu Giken Co. Ltd., Fukuoka (Japan); Hirose, T. [Kumamoto Univ. (Japan). Faculty of Engineering

1998-03-01

On the honeycomb type adsorptive concentrator, a manufacturing method of the honeycomb adsorbent rotor, retention of mechanical strength corresponding with a large-scale processing and minimization of air leakage resulting in performance deterioration were technically examined. Honeycomb structure was formed from an alumina-silica fiber paper, and high silica-content zeolite was deposited in the fiber void of the matrix. The adsorbent rotor using sepiolite as an inorganic adhesive for honeycomb fabrication showed fracture strength of from 1.6 to 3.2 times the conventional adsorbent rotor. Two types of differently shaped fluorinated rubber seal were developed for the adsorbent rotor. Amount of air leakage from the seal between each zone as well as to outside was sufficiently small. A large-scale VOC concentrator with the 3950 mm diameter and 450 mm length was manufactured with the adsorbent rotor and seal structure in accordance with the aforementioned method. Results of the real machine operation showed same concentration performance at those of the small-scale experiment. 10 refs., 15 figs., 2 tabs.

Developing strategies for the regeneration of polyethylenimine based CO{sub 2} adsorbents

Energy Technology Data Exchange (ETDEWEB)

Trevor C. Drage; Karl M. Smith; Ana Arenillas; Colin E. Snape [University of Nottingham, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre, School of Chemical, Environmental and Mining Engineering

2007-07-01

Adsorption is considered to be one of the more promising technologies for capturing CO{sub 2} from flue gases. The efficient adsorption of CO{sub 2} at low partial pressures, associated with post-combustion capture, require chemical type adsorbents containing basic amine functional groups. It has been demonstrated that amine polymers, for example polyethylenimine (PEI), immobilised on various porous substrates, silica, zeolites and fly ash, are effective adsorbents for CO{sub 2}. When considering the use of adsorption for large scale CO{sub 2} capture, the ease of regeneration and the lifetime of the adsorbents are critical factors in determining their efficiency, cost and therefore feasibility for use. In this paper two approaches, thermal swing adsorption (TSA) cycles over a range of temperatures and time in an atmosphere of CO{sub 2} and thermally assisted pressure swing desorption, are explored for the regeneration of the PEI based adsorbents. The reactions occurring during the TSA regeneration of PEI based adsorbents in an atmosphere of CO{sub 2}, especially the formation of a thermostable complex between PEI and CO{sub 2} above 130{sup o}C are described. Identification of the complex by FTIR, XPS and 13C NMR and its attempted regeneration will be described. Overall, the results from this research have implications for the selection of regeneration strategies of all amine based CO{sub 2} adsorbents. 5 refs., 1 figs., 1 tab.

EDTA-functionalized clinoptilolite nanoparticles as an effective adsorbent for Pb(II) removal.

Science.gov (United States)

Eshraghi, Farahnaz; Nezamzadeh-Ejhieh, Alireza

2018-03-08

An efficient Pb(II) adsorbent was prepared by the modification of clinoptilolite nanoparticles (CpN) with ethylenediaminetetraacetic acid (EDTA). Samples were characterized by XRD, FT-IR, SEM, BET, TG-DTG, CHNS analyzer, and energy dispersive analysis X-ray spectroscopy (EDX). The experiments were designed by response surface methodology (RSM) based on central composite design (CCD) that suggested a quadratic model to predict the conditions and the interactions between the variables including adsorbent dosage, removal time, C Pb , and its solution pH. Adequacy of the suggested quadratic model was judged by ANOVA. The maximum Pb(II) removal of 0.27 mmol Pb(II) /g ads was achieved in optimal run including adsorbent dosage 2 g L -1 , removal time 271 min, C Pb 22.51 mmol L -1 , and Pb(II) solution pH 5.88. In binary metal cation systems including 1000 mg L -1 with respect to both Pb(II) and interfering cations, good selectivity of CpN-EDTA adsorbent was observed towards Pb(II) among the tested cations except Fe(III). Adsorption isotherm of lead removal by the adsorbent was well modeled by Langmuir equation, indicating a monolayer sorption of Pb(II) onto the adsorbent. The pseudo-second-order rate equation, indicating chemical reaction rate limiting step for the process, well modeled the kinetic of the process. An exothermic and spontaneous process was confirmed by the negative ∆H and ∆G.

Studies on some influential factors of the zinc-activated carbon composite adsorbent on adsorptivity for uranium

International Nuclear Information System (INIS)

Miyai, Yoshitaka; Kitamura, Takao; Takagi, Norio; Katoh, Shunsaku; Miyazaki, Hidetoshi

1978-01-01

Factors, which influence the uranium adsorption of powdery composite adsorbent of basic zinc carbonate and activated carbon were studied. In the range studied, zinc content of the adsorbent was the most influential factor on the uranium adsorption, and the second influential factor was sea water volume and the third factor was adsorption period. Interactive effects were observed between zinc content and sea water volume, and between zinc content and adsorption period, and it was deduced that there existed the optimum value of sea water volume and adsorption period respectively for the zinc content of the adsorbent. Maximum uranium adsorption of adsorbent with 40% zinc content was observed at sea water volume of 15 liters and adsorption period of 25 hrs. As for temperature in the range of 15 - 35 0 C, the lower the temperature, the larger amount of adsorbed uranium was. The powdery adsorbent was made into granule, and its strength and its uranium adsorptivity were studied in relation to the granulating conditions. By use of PVA with degree of polymerization above 1,700 as binder, the granular adsorbent with the same strength as commercial granular activated carbon was obtained. PVA amount and its degree of polymerization gave only small effect on uranium adsorption of the adsorbent. Effect of granule size on the uranium adsorption rate in the range of 1 - 4 mm was that the uranium adsorption rate changed proportionally to surface area of assumed sphere. As a test for practical use, five times repetitions of adsorption and desorption were carried out on the same granular adsorbent. During the repetition the amount of adsorbed uranium rather increased, and desorption ratio of adsorbed uranium was constant at 91 - 93%. The weight loss of the adsorbent in a cycle of adsorption and desorption was about 3%. (author)

Application of chitin and zeolite adsorbents for treatment of low level radioactive liquid wastes

International Nuclear Information System (INIS)

Moattar, F.; Hayeripour, S.

2004-01-01

Two types of shrimp chitin derivatives and two types of Iranian natural zeolite derivates were studied for adsorption and treatment of low-level radioactive liquid waste. Chitin with lowers than 10% and chitosan with higher than 90% deacetylation factor were selected as neutral organic adsorbents. Natural clinoptilolite of Firuzkooh area and Na from derivates of it were selected as natural inorganic adsorbents. The static and dynamic ion exchange experimental results show that the ad adsorption efficiency depend on particle size, Ph, adsorbent type, deacetylation factor ( in chitin adsorbents) and cation type. The best Cs adsorption occurred in Na from clinoptilolite. Nevertheless chitin derivatives, particularly chitosan, are more efficient than zeolite adsorbents for removing of radionuclides such as 137 Cs, 54 Mn, 90 Sr and 60 Co. Adsorption performance was discussed and compared with each other

ε-Polylysine-based thermo-responsive adsorbents for immunoglobulin adsorption-desorption under mild conditions.

Science.gov (United States)

Maruyama, Masashi; Shibuya, Keisuke

2017-08-22

Thermo-responsive adsorbents for immunoglobulin G (IgG) employing ε-polylysine (EPL) as a polymer backbone were developed. The introduction of mercaptoethylpyridine (MEP) as an IgG-binding ligand and hydrophobization of side chains afforded thermo-responsive IgG adsorbents, whose thermo-responsive IgG desorption ratio was up to 88% (EPL/MEP derivative 3m). The changes in surface densities of active MEP groups, which are caused by thermal conformational changes of the adsorbents, play key roles for IgG desorption. Although a trade-off of IgG adsorption capacity and IgG desorption ratio was observed, the present study offers a novel molecular design for thermo-responsive adsorbents with high synthetic accessibility and potentially low toxicity.

Removal of radium from aqueous solutions using adsorbent produced from coconut coir pith

International Nuclear Information System (INIS)

Zalina Laili; Muhamat Omar; Mohd Zaidi Ibrahim; Esther Phillip; Mohd Abdul Wahab Yusof; Hassan, A.

2008-08-01

A study was conducted to evaluate the potential use of the coconut coir pith as an adsorbent for the removal of radium from aqueous solutions. Experiments to establish adsorptions as a function of pH and contact time were carried out. The results showed that radium adsorption are dependent upon pH and contact time of coconut coir pith with aqueous solutions. 70-80% of radium were adsorbed in the neutral to alkaline pH range. The amount of radium adsorbed also increased with contact time, reaching an optimum after 250 min. Thus, it can be concluded that the coconut coir pith has the potential to be used as an adsorbent in radium removal from aqueous solutions. (Author)

Infrared Analysis Of Enzymes Adsorbed Onto Model Surfaces

Science.gov (United States)

Story, Gloria M.; Rauch, Deborah S.; Brode, Philip F.; Marcott, Curtis A.

1989-12-01

The adsorption of the enzymes, subtilisin BPN' and lysozyme, onto model surfaces was examined using attenuated total reflectance (ATR) infrared (IR) spectroscopy. Using a cylindrical internal reflection (CIRcle) cell with a Germanium (Ge) internal reflection element (IRE), model hydrophilic surfaces were made by plasma cleaning the IRE and model hydrophobic surfaces were made by precoating the IRE with a thin film of polystyrene. Gas chromatography (GC)-IR data collection software was used to monitor adsorption kinetics during the first five minutes after injection of the enzyme into the CIRcle cell. It was found that for both lysozyme and BPN', most of the enzyme that was going to adsorb onto the model surface did so within ten seconds after injection. Nearly an order-of-magnitude more BPN' adsorbed on the hydrophobic Ge surface than the hydrophilic one, while lysozyme adsorbed somewhat more strongly to the hydrophilic Ge surface. Overnight, the lysozyme layer continued to increase in thickness, while BPN' maintained its initial coverage. The appearance of carboxylate bands in some of the adsorbed BPN' spectra suggests the occurrence of peptide bond hydrolysis. A Au/Pd coating on the CIRcle cell o-rings had a significant effect on the adsorption of BPN'. (This coating was applied in an attempt to eliminate interfering Teflon absorption bands.) An apparent electrochemical reaction occurred, involving BPN', Ge, Au/Pd, and the salt solution used to stabilize BPN'. The result of this reaction was enhanced adsorption of the enzyme around the coated o-rings, etching of the Ge IRE at the o-ring site, and some autolysis of the enzyme. No such reaction was observed with lysozyme.

Synthesis and properties of a high-capacity iron oxide adsorbent for fluoride removal from drinking water

Science.gov (United States)

Zhang, Chang; Li, Yingzhen; Wang, Ting-Jie; Jiang, Yanping; Fok, Jason

2017-12-01

A novel iron oxide adsorbent with a high fluoride adsorption capacity was prepared by a facile wet-chemical precipitation method and ethanol treatment. The ethanol-treated adsorbent was amorphous and had a high specific surface area. The adsorption capacity of the treated adsorbent was much higher than that of untreated adsorbent. The Langmuir maximum adsorption capacity of the adsorbent prepared at a low final precipitation pH (≤9.0) and treated with ethanol reached 60.8 mg/g. A fast adsorption rate was obtained, and 80% of the adsorption equilibrium capacity was achieved within 2 min. The adsorbent had high fluoride-removal efficiency for water in a wide initial pH range of 3.5-10.3 and had a high affinity for fluoride in the presence of common co-anions. The ethanol treatment resulted in structure transformation of the adsorbent by inhibiting the crystallization of the nano-precipitates. The adsorption was confirmed to be ion exchange between fluoride ions and the hydroxyl groups on the adsorbent surface.

Fast Removal of Polybrominated Diphenyl Ethers from Aqueous Solutions by Using Low-Cost Adsorbents

Directory of Open Access Journals (Sweden)

Renin Chang

2017-01-01

Full Text Available 4-Dibromodiphenyl ether (BDE-3 and 4,4′-dibromodiphenyl ether (BDE-15 are two of the major polybrominated diphenyl ethers used as flame-retardant additives in computer main boards and in fireproof building materials. In this study, we evaluated the potential of three low-cost adsorbents, black tea, green tea, and coconut palm leaf powders, to adsorb BDE-3 and BDE-15 from aqueous solutions. The results showed that pressure steam washing of the adsorbents increased their capacities to adsorb BDE-3 and BDE-15. The maximum adsorption capacities of pressure steam–washed black tea, green tea, and coconut palm leaf powders were 21.85 mg·L−1, 14.56 mg·L−1 and 22.47 mg·L−1, respectively. The results also showed that the adsorption equilibrium (qe was achieved at 4 min. Moreover, 97.8% of BDE-3 and 98.5% of BDE-15 could be removed by adsorbents pretreated with pressure steam washing. The kinetic data fitted well with a pseudo-second-order equation. The adsorption rate constants (k2 of all pressure steam–washed adsorbents ranged from 8.16 × 10−3 to 6.61 × 10−2 g·(mg·L−1−1·s−1, and the amount adsorbed at qe by all pressure steam–washed adsorbents ranged from 4.21 to 4.78 mg·L−1. Green alga Chlorella vulgaris was used as the test organism and the median effective concentration values of BDE-3 and BDE-15 were 7.24 and 3.88 mg·L−1, respectively. After BDE-3 and BDE-15 were removed from the solution, their biotoxicities markedly decreased. These findings indicate that these low-cost adsorbents can be used to remove BDE-3 and BDE-15 from aqueous solutions and wastewater.

Development of Silver-exchanged Adsorbents for the Removal of Fission Iodine from Alkaline Dissolution

Energy Technology Data Exchange (ETDEWEB)

Kim, Tae Woon; Lee, Seung Kon; Lee, Su Seung; Lee, Jun Sig [KAERI, Daejeon (Korea, Republic of); Kim, Sang Wook [Dongguk University, Gyeongju (Korea, Republic of)

2016-05-15

{sup 99} Mo is extracted from the filtrate solution through column-based multistep separation and purification process. In the process, removal of radio-impurities from the solution is essential to acquire high-quality fission {sup 99} Mo. Iodine is the main impurity having about 15% of total radioactivity among the whole fission products. Most of the iodine exists in the caustic dissolution as iodide form. In this study, silver-exchanged adsorbent is used to adsorb iodide from the solution. Adsorbed iodide can be recovered and recycled for radiopharmaceuticals. Compound is dried again. After heating ascorbic acid solution, solution is added to dried compound. Heat the mixture. After removing supernatant, the mixture is washed with hot distilled water and then cool distilled water in the order named. Finally, the mixture is heated and then recovering by using the sieve. In this study, silver-exchanged adsorbent is used to adsorb iodide from the solution. Adsorbed iodide can be recovered and recycled for radiopharmaceuticals. Silver-doped DAW-70 alumina by using silver mirror reaction is less impurities and simpler than method using ascorbic acid.