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Sample records for monocarbonyl cations neutrals

  1. Mass spectral analysis of cationic and neutral technetium complexes

    International Nuclear Information System (INIS)

    Unger, S.E.; McCormick, T.J.; Nunn, A.N.; Treher, E.N.

    1986-01-01

    Cationic and neutral technetium compounds have been characterized by mass spectrometry using a variety of ionization methods. These compounds include octahedral cationic complexes containing phosphorous and arsenic ligands such as DIPHOS and DIARS and neutral complexes containing PnAO and dimethylglyoxime, DMG, or cyclohexanedione dioxime, CDO, ligands. Boronate esters incorporating methyl and butyl derivatives of the DMG and CDO dioximes represent a new class of seven-coordinate Tc radiopharmaceuticals whose characterization by mass spectrometry has not previously been described. These complexes show promise as myocardial imaging agents. (author)

  2. Density functional study of carbon monoxide adsorption on small cationic, neutral, and anionic aluminum nitride clusters

    Science.gov (United States)

    Guo, Ling

    CO adsorption on small cationic, neutral, and anionic (AlN)n (n = 1-6) clusters has been investigated using density functional theory in the generalized gradient approximation. Among various possible CO adsorption sites, an N on-top (onefold coordinated) site is found to be the most favorable one, irrespective of the charge state of the clusters. The adsorption energies of CO on the anionic (AlN)nCO (n = 2-4) clusters are greater than those on the neutral and cationic complexes. The adsorption energies on the cationic and neutral complexes reflect the odd-even oscillations, and the adsorption energies of CO on the cationic (AlN)nCO (n = 5, 6) clusters are greater than those on the neutral and anionic complexes. The adsorption energies for the different charge states decrease with increasing cluster size.

  3. Photoinduced Dynamics of Neutral, Cationic, and Anionic Species

    DEFF Research Database (Denmark)

    Stephansen, Anne Boutrup

    . The investigations have primarily employed femtosecond time-resolved photoionization or photodetachment techniques. Intersystem crossing (ISC) in neutral organic species is conventionally assumed to be slow due to the spin-forbidden nature of the process; this assumption has been challenged during the past decade...

  4. CO hydrogenation on zeolite-supported Ru: Effect of neutralizing cations

    International Nuclear Information System (INIS)

    Oukaci, R.; Wu, J.C.S.; Goodwin, J.G. Jr.

    1986-01-01

    Previous results for zeolite-supported Ru prepared by ion exchange suggested a possible effect of the nature and concentration of the neutralizing cations in the zeolite on the catalytic properties of the metal. However, the interpretation of these results was complicated by the fact that a series of zeolites with different Si/Al ratios was used. The present study was undertaken to investigate systematically the influence of the nature of alkali neutralizing cations on CO hydrogenation over ion-exchanged Y-zeolite-supported ruthenium catalysts

  5. Biophysical mechanisms of endotoxin neutralization by cationic amphiphilic peptides.

    Science.gov (United States)

    Kaconis, Yani; Kowalski, Ina; Howe, Jörg; Brauser, Annemarie; Richter, Walter; Razquin-Olazarán, Iosu; Iñigo-Pestaña, Melania; Garidel, Patrick; Rössle, Manfred; Martinez de Tejada, Guillermo; Gutsmann, Thomas; Brandenburg, Klaus

    2011-06-08

    Bacterial endotoxins (lipopolysaccharides (LPS)) are strong elicitors of the human immune system by interacting with serum and membrane proteins such as lipopolysaccharide-binding protein (LBP) and CD14 with high specificity. At LPS concentrations as low as 0.3 ng/ml, such interactions may lead to severe pathophysiological effects, including sepsis and septic shock. One approach to inhibit an uncontrolled inflammatory reaction is the use of appropriate polycationic and amphiphilic antimicrobial peptides, here called synthetic anti-LPS peptides (SALPs). We designed various SALP structures and investigated their ability to inhibit LPS-induced cytokine secretion in vitro, their protective effect in a mouse model of sepsis, and their cytotoxicity in physiological human cells. Using a variety of biophysical techniques, we investigated selected SALPs with considerable differences in their biological responses to characterize and understand the mechanism of LPS inactivation by SALPs. Our investigations show that neutralization of LPS by peptides is associated with a fluidization of the LPS acyl chains, a strong exothermic Coulomb interaction between the two compounds, and a drastic change of the LPS aggregate type from cubic into multilamellar, with an increase in the aggregate sizes, inhibiting the binding of LBP and other mammalian proteins to the endotoxin. At the same time, peptide binding to phospholipids of human origin (e.g., phosphatidylcholine) does not cause essential structural changes, such as changes in membrane fluidity and bilayer structure. The absence of cytotoxicity is explained by the high specificity of the interaction of the peptides with LPS. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  6. Neutral glycoconjugated amide-based calix[4]arenes: complexation of alkali metal cations in water.

    Science.gov (United States)

    Cindro, Nikola; Požar, Josip; Barišić, Dajana; Bregović, Nikola; Pičuljan, Katarina; Tomaš, Renato; Frkanec, Leo; Tomišić, Vladislav

    2018-02-07

    Cation complexation in water presents a unique challenge in calixarene chemistry, mostly due to the fact that a vast majority of calixarene-based cation receptors is not soluble in water or their solubility has been achieved by introducing functionalities capable of (de)protonation. Such an approach inevitably involves the presence of counterions which compete with target cations for the calixarene binding site, and also rather often requires the use of ion-containing buffer solutions in order to control the pH. Herein we devised a new strategy towards the solution of this problem, based on introducing carbohydrate units at the lower or upper rim of calix[4]arenes which comprise efficient cation binding sites. In this context, we prepared neutral, water-soluble receptors with secondary or tertiary amide coordinating groups, and studied their complexation with alkali metal cations in aqueous and methanol (for the comparison purpose) solutions. Complexation thermodynamics was quantitatively characterized by UV spectrometry and isothermal titration calorimetry, revealing that one of the prepared tertiary amide derivatives is capable of remarkably efficient (log K ≈ 5) and selective binding of sodium cations among alkali metal cations in water. Given the ease of the synthetic procedure used, and thus the variety of accessible analogues, this study can serve as a platform for the development of reagents for diverse purposes in aqueous media.

  7. Optimizing cationic and neutral lipids for efficient gene delivery at high serum content.

    Science.gov (United States)

    Chan, Chia-Ling; Ewert, Kai K; Majzoub, Ramsey N; Hwu, Yeu-Kuang; Liang, Keng S; Leal, Cecília; Safinya, Cyrus R

    2014-01-01

    Cationic liposome (CL)-DNA complexes are promising gene delivery vectors with potential application in gene therapy. A key challenge in creating CL-DNA complexes for application is that their transfection efficiency (TE) is adversely affected by serum. In particular, little is known about the effects of a high serum content on TE, even though this may provide design guidelines for application in vivo. We prepared CL-DNA complexes in which we varied the neutral lipid [1,2-dioleoyl-sn-glycerophosphatidylcholine, glycerol-monooleate (GMO), cholesterol], the headgroup charge and chemical structure of the cationic lipid, and the ratio of neutral to cationic lipid; we then measured the TE of these complexes as a function of serum content and assessed their cytotoxicity. We tested selected formulations in two human cancer cell lines (M21/melanoma and PC-3/prostate cancer). In the absence of serum, all CL-DNA complexes of custom-synthesized multivalent lipids show high TE. Certain combinations of multivalent lipids and neutral lipids, such as MVL5(5+)/GMO-DNA complexes or complexes based on the dendritic-headgroup lipid TMVLG3(8+) exhibited high TE both in the absence and presence of serum. Although their TE still dropped to a small extent in the presence of serum, it reached or surpassed that of benchmark commercial transfection reagents, particularly at a high serum content. Two-component vectors (one multivalent cationic lipid and one neutral lipid) can rival or surpass benchmark reagents at low and high serum contents (up to 50%, v/v). We propose guidelines for optimizing the serum resistance of CL-DNA complexes based on a given cationic lipid. Copyright © 2014 John Wiley & Sons, Ltd.

  8. Synthesis, Structure and Reactivity of a Borylene Cation [(NHSi)2B(CO)]+ Stabilized by Three Neutral Ligands.

    Science.gov (United States)

    Wang, Hao; Wu, Linlin; Lin, Zhenyang; Xie, Zuowei

    2017-10-04

    A borylene cation stabilized by bis(silylene) and carbon monoxide was prepared and structurally characterized via the reaction of bis(silylene)-stabilized bromoborylene with W(CO) 6 . This is the first example of a borylene cation coordinated by three neutral ligands, which can be viewed as a cationic form of a long-sought Lewis base-stabilized zerovalent boron compound. This cation can cleave dihydrogen.

  9. A density functional study of carbon monoxide adsorption on small cationic, neutral, and anionic gold clusters

    Science.gov (United States)

    Wu, X.; Senapati, L.; Nayak, S. K.; Selloni, A.; Hajaligol, M.

    2002-08-01

    CO adsorption on small cationic, neutral, and anionic Aun (n=1-6) clusters has been investigated using density functional theory in the generalized gradient approximation. Among various possible CO adsorption sites, the on-top (one-fold coordinated) is found to be the most favorable one, irrespective of the charge state of the cluster. In addition, planar structures are preferred by both the bare and the CO-adsorbed clusters. The adsorption energies of CO on the cationic clusters are generally greater than those on the neutral and anionic complexes, and decrease with size. The adsorption energies on the anions, instead, increase with cluster size and reach a local maximum at Au5CO-, in agreement with recent experiment. The differences in adsorption energies for the different charge states decrease with increasing cluster size.

  10. Photodegradable neutral-cationic brush block copolymers for nonviral gene delivery.

    Science.gov (United States)

    Hu, Xianglong; Li, Yang; Liu, Tao; Zhang, Guoying; Liu, Shiyong

    2014-08-01

    We report on the fabrication of a photodegradable gene-delivery vector based on PEO-b-P(GMA-g-PDMAEMA) neutral-cationic brush block copolymers that possess cationic poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA) brushes for DNA compaction, poly(ethylene oxide) (PEO) as a hydrophilic block, and poly(glycidyl methacrylate) (PGMA) as the backbone. The PEO-b-P(GMA-g-PDMAEMA) copolymers were synthesized through the combination of reversible addition-fragmentation transfer (RAFT) polymerization and postmodification. A photocleavable PEO-based macroRAFT agent was first synthesized; next, the PEO-b-PGMA block copolymer was prepared by RAFT polymerization of GMA; this was followed by a click reaction to introduce the RAFT initiators on the side chains of the PGMA block; then, RAFT polymerization of DMAEMA afforded the PEO-b-P(GMA-g-PDMAEMA) copolymer. The obtained neutral-cationic brush block copolymer could effectively complex plasmid DNA (pDNA) into nanoparticles at an N/P ratio (i.e., the number of nitrogen residues per DNA phosphate) of 4. Upon UV irradiation, pDNA could be released owing to cleavage of the pDNA-binding cationic PDMAEMA side chains as well as the nitrobenzyl ester linkages at the diblock junction point. In addition, in vitro gene transfection results demonstrated that the polyplexes could be effectively internalized by cells with good transfection efficiency, and the UV irradiation protocol could considerably enhance the efficiency of gene transfection. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Gas-Phase Energetics of Actinide Oxides: An Assessment of Neutral and Cationic Monoxides and Dioxides from Thorium to Curium

    Science.gov (United States)

    Marçalo, Joaquim; Gibson, John K.

    2009-09-01

    An assessment of the gas-phase energetics of neutral and singly and doubly charged cationic actinide monoxides and dioxides of thorium, protactinium, uranium, neptunium, plutonium, americium, and curium is presented. A consistent set of metal-oxygen bond dissociation enthalpies, ionization energies, and enthalpies of formation, including new or revised values, is proposed, mainly based on recent experimental data and on correlations with the electronic energetics of the atoms or cations and with condensed-phase thermochemistry.

  12. Non-Cationic Proteins Are Associated with HIV Neutralizing Activity in Genital Secretions of Female Sex Workers.

    Science.gov (United States)

    Birse, Kenzie D M; Cole, Amy L; Hirbod, Taha; McKinnon, Lyle; Ball, Terry B; Westmacott, Garrett R; Kimani, Joshua; Plummer, Frank; Cole, Alexander M; Burgener, Adam; Broliden, Kristina

    2015-01-01

    Cationic proteins found in cervicovaginal secretions (CVS) are known to contribute to the early antiviral immune response against HIV-infection in vitro. We here aimed to define additional antiviral factors that are over-expressed in CVS from female sex workers at high risk of infection. CVS were collected from Kenyan HIV-seronegative (n = 34) and HIV-seropositive (n = 12) female sex workers, and were compared with those from HIV-seronegative low-risk women (n = 12). The highly exposed seronegative (HESN) sex workers were further divided into those with less (n = 22) or more (n = 12) than three years of documented sex work. Cationic protein-depleted CVS were assessed for HIV-neutralizing activity by a PBMC-based HIV-neutralizing assay, and then characterized by proteomics. HIV neutralizing activity was detected in all unprocessed CVS, however only CVS from the female sex worker groups maintained its HIV neutralizing activity after cationic protein-depletion. Differentially abundant proteins were identified in the cationic protein-depleted secretions including 26, 42, and 11 in the HESN>3 yr, HESNHIV-positive groups, respectively. Gene ontology placed these proteins into functional categories including proteolysis, oxidation-reduction, and epidermal development. The proteins identified in this study include proteins previously associated with the HESN phenotype in other cohorts as well as novel proteins not yet associated with anti-HIV activities. While cationic proteins appear to contribute to the majority of the intrinsic HIV neutralizing activity in the CVS of low-risk women, a broader range of non-cationic proteins were associated with HIV neutralizing activity in HESN and HIV-positive female sex workers. These results indicate that novel protein factors found in CVS of women with high-risk sexual practices may have inherent antiviral activity, or are involved in other aspects of anti-HIV host defense, and warrant further exploration into their mode of action.

  13. Electrogenerated chemiluminescence of a cationic cyclometalated iridium complex–Nafion modified electrode in neutral aqueous solution

    International Nuclear Information System (INIS)

    Dong, YongPing; Ni, ZiYue; Zhang, Jing; Tong, BiHai; Chu, XiangFeng

    2013-01-01

    Electrogenerated chemiluminescence (ECL) of a cationic cyclometalated iridium complex, [(pqcm) 2 Ir(bpy)](PF 6 ) (1, pqcmH=2-phenyl-quinoline-4-carboxylic acid methyl ester, bpy=2,2′-bipyridine), was investigated at a bare glassy carbon electrode in CH 3 CN solution and 4 ECL peaks were observed. Then, the ECL of the iridium complex was studied in neutral phosphate buffer solution (PBS) by immobilizing it on a glassy carbon electrode. Two closely located ECL peaks were obtained at 1.07 and 1.40 V when the potential was scanned from −3.00 V to 2.20 V, while only one broad ECL peak located around −2.0 V was obtained when the potential was scanned from 2.20 V to −3.00 V. In the presence of oxalate, one ECL peak located around 1.22 V could be obtained except the broad ECL peak located at −2.00 V. The ECL peak at positive potential range was enhanced more than one magnitude in the presence of Nafion and was nearly 5-times higher than that of Ru(bpy) 3 2+ –Nafion modified electrode, suggesting that the synthesized iridium complex has great application potential in ECL detection. The ECL spectra of iridium complex were identical to its photoluminescence spectrum, indicating the same metal-to-ligand charge transfer (MLCT) excited states. The mechanisms of ECL were proposed based on the experimental results. The present ECL sensor gave a linear response for the oxalate concentration from 1.0×10 −6 to 1.0×10 −4 mol L −1 with a detection limit (S/N=3) of 9.1×10 −7 mol L −1 . -- Graphical abstract: Electrochemiluminescence (ECL) of immobilized novel cationic cyclometalated iridium complex in neutral phosphate buffer solution is reported for the first time. The intensity of iridium complex ECL is 5-times higher than that of Ru(bpy) 3 2+ ECL. Highlights: ► Cationic cyclometalated iridium complex was modified on a bare electrode. ► Electrochemiluminescence (ECL) of the modified electrode was studied. ► The ECL intensity is higher than that of Ru

  14. Kinetics of ion-ion mutual neutralization: Halide anions with polyatomic cations

    Energy Technology Data Exchange (ETDEWEB)

    Shuman, Nicholas S.; Wiens, Justin P.; Miller, Thomas M.; Viggiano, Albert A., E-mail: rvborgmailbox@kirtland.af.mil [Space Vehicles Directorate, Air Force Research Laboratory, Kirtland Air Force Base, Albuquerque, New Mexico 87117 (United States)

    2014-06-14

    The binary mutual neutralization (MN) of a series of 17 cations (O{sub 2}{sup +}, NO{sup +}, NO{sub 2}{sup +}, CO{sup +}, CO{sub 2}{sup +}, Cl{sup +}, Cl{sub 2}{sup +}, SO{sub 2}{sup +}, CF{sub 3}{sup +}, C{sub 2}F{sub 5}{sup +}, NH{sub 3}{sup +}, H{sub 3}{sup +}, D{sub 3}{sup +}, H{sub 2}O{sup +}, H{sub 3}O{sup +}, ArH{sup +}, ArD{sup +}) with 3 halide anions (Cl{sup −}, Br{sup −}, I{sup −}) has been investigated in a flowing afterglow-Langmuir probe apparatus using the variable electron and neutral density attachment mass spectrometry technique. The MN rate constants of atom-atom reactions are dominated by the chemical nature of the system (i.e., the specific locations of curve crossings). As the number of atoms in the system increases, the MN rate constants become dominated instead by the physical nature of the system (e.g., the relative velocity of the reactants). For systems involving 4 or more atoms, the 300 K MN rate constants are well described by 2.7 × 10{sup −7} μ{sup −0.5}, where the reduced mass is in Da and the resulting rate constants in cm{sup 3} s{sup −1}. An upper limit to the MN rate constants appears well described by the complex potential model described by Hickman assuming a cross-section to neutralization of 11 000 Å{sup 2} at 300 K, equivalent to 3.5 × 10{sup −7} μ{sup −0.5}.

  15. Antibacterial activity and safety of commercial veterinary cationic steroid antibiotics and neutral superoxidized water.

    Directory of Open Access Journals (Sweden)

    Benjamin E Bergstrom

    Full Text Available Antibiotic resistance of bacteria common to the ocular surface is an evolving problem. Thus, novel treatment options with new modes of action are required. We investigated the antibacterial activity and safety of three commercially available topical veterinary ophthalmic products (cationic steroid antibiotics, products A and B, and a neutral superoxidized water, product C to determine their potential use as antimicrobial alternatives. The minimum inhibitory concentrations (MIC of the three products were determined against 17 antibiotic resistant bacterial clinical isolates from the ocular surface. Using a standard cytotoxicity assay, the products at varying concentrations were evaluated with a corneal fibroblast cell line and a macrophage-like cell line to determine their potential toxic effect in vitro. The commercial ophthalmic solutions, ofloxacin 0.3%, tobramycin 0.3% and gentamicin 0.3% were used as positive controls for the MIC and tobramycin 0.3% was used as positive control for the cytotoxicity assays. For the MIC, Product C showed no inhibition of growth for any organisms, while Products A and B showed inhibition of growth similar to slightly less than the positive controls. For the cytotoxicity assays, Product C exhibited minimal toxicity while Products A and B exhibited toxicity similar to the controls. In conclusion, Product C had no antibacterial activity in these assays, while Products A and B had antibacterial profiles similar to slightly less than common topical ophthalmic antibiotics and cytotoxicity profiles similar to common topical ophthalmic antibiotics. To our knowledge, this is the first report on the antibacterial activity and safety of the cationic steroid antibiotics and superoxidized water.

  16. Methyl Cation Affinities of Neutral and Anionic Maingroup-Element Hydrides: Trends Across the Periodic Table and Correlation with Proton Affinities

    NARCIS (Netherlands)

    Mulder, R. Joshua; Guerra, Celia Fonseca; Bickelhaupt, F. Matthias

    2010-01-01

    We have computed the methyl cation affinities in the gas phase of archetypal anionic and neutral bases across the periodic table using ZORA-relativistic density functional theory (DFT) at BP86/QZ4P//BP86/TZ2P. The main purpose of this work is to provide the methyl cation affinities (and

  17. Catalytic Hydroamination of Alkynes and Norbornene with Neutral and Cationic Tantalum Imido Complexes

    Science.gov (United States)

    Anderson, Laura L.; Arnold, John; Bergman, Robert G.

    2005-01-01

    Several tantalum imido complexes have been synthesized and shown to efficiently catalyze the hydroamination of internal and terminal alkynes. An unusual hydroamination/hydroarylation reaction of norbornene catalyzed by a highly electrophilic cationic tantalum imido complex is also reported. Factors affecting catalyst activity and selectivity are discussed along with mechanistic insights gained from stoichiometric reactions. PMID:15255680

  18. Pearl-necklace complexes of flexible polyanions with neutral-cationic diblock copolymers

    NARCIS (Netherlands)

    Golinska, M.D.; Wolf, de F.A.; Cohen Stuart, M.A.; Hernandez Garcia, A.; Vries, de R.J.

    2013-01-01

    We study the complexation of very asymmetric diblock copolymers (consisting of a cationic block of 12 lysines connected to a 400 amino acid long hydrophilic polypeptide block with a net charge that is nearly zero) with oppositely charged sodium poly(acrylic acid) (NaPAA) with a range of molar masses

  19. Effect of the Cationic Block Structure on the Characteristics of Sludge Flocs Formed by Charge Neutralization and Patching

    Directory of Open Access Journals (Sweden)

    Huaili Zheng

    2017-05-01

    Full Text Available In this study, a template copolymer (TPAA of (3-Acrylamidopropyl trimethylammonium chloride (AATPAC and acrylamide (AM was successfully synthesized though ultrasonic-initiated template copolymerization (UTP, using sodium polyacrylate (PAAS as a template. TPAA was characterized by an evident cationic microblock structure which was observed through the analyses of the reactivity ratio, Fourier transform infrared spectroscopy (FTIR, 1H (13C nuclear magnetic resonance spectroscopy (1H (13C NMR, and thermogravimetry/differential scanning calorimetry (TG/DSC. The introduction of the template could improve the monomer (AATPAC reactivity ratio and increase the length and amount of AATPAC segments. This novel cationic microblock structure extremely enhanced the ability of charge neutralization, patching, and bridging, thus improving the activated sludge flocculation performance. The experiments of floc formation, breakage, and regrowth revealed that the cationic microblock structure in the copolymer resulted in large and compact flocs, and these flocs had a rapid regrowth when broken. Finally, the larger and more compact flocs contributed to the formation of more channels and voids, and therefore the specific resistance to filtration (SRF reached a minimum.

  20. Cationic and neutral copper(I) iodide cluster MOFs derived from ...

    Indian Academy of Sciences (India)

    Ashok Yadav

    These reactions yielded two new cluster-MOFs 2 and 3. While the ..... (a) Ortep plots at 50% ellipsoid probabilities for the cationic segments of 2; (b) View of the. 3D-MOF assembly of 2 ... identical emission colour of 2 at 298 K and 77 K under the. UV-lamp. .... C 2013 A multi-metal-cluster MOF with Cu4I4 and. Cu6S6 as ...

  1. A Study of Complexation-ability of Neutral Schiff Bases to Some Metal Cations

    OpenAIRE

    Topal, Giray; Tümerdem, Recep; Basaran, Ismet; Gümüş, Arzu; Cakir, Umit

    2007-01-01

    The constants of the extraction equilibrium and the distribution for dichloromethane as an organic solvent having low dielectric constant of metal cations with chiral Schiff bases, benzaldehydene-(S)-2-amino-3-phenylpropanol (I), ohydroxybenzaldehydene-( S)-2-amino-3-phenyl-propanol (II), benzaldehydene-(S)-2- amino-3-methylbutanol (III) with anionic dyes [4-(2-pyridylazo)-resorcinol mono sodium monohydrate (NaPar), sodium picrat (NaPic) and potassium picrat (KPic)] and some heavy metal chlor...

  2. Double hydrogen atom transfer in lactamide radical cations via ion-neutral complexes

    Science.gov (United States)

    Friedrichs, Heike; McGibbon, Graham A.; Schwarz, Helmut

    1996-02-01

    Tandem mass spectrometry experiments on lactamide and deuterium-labelled isotopomers show that the reaction of metastable ions CH3CH(OH)CONH2·+ --> CH3CO· + HC(OH)NH2+ occurs via ion-neutral complexes. The experimental findings are complemented by density functional theory calculations.

  3. Structure and spectroscopic properties of neutral and cationic tetratomic [C,H,N,Zn] isomers: A theoretical study

    Science.gov (United States)

    Redondo, Pilar; Largo, Antonio; Vega-Vega, Álvaro; Barrientos, Carmen

    2015-05-01

    The structure and spectroscopic parameters of the most relevant [C,H,N,Zn] isomers have been studied employing high-level quantum chemical methods. For each isomer, we provide predictions for their molecular structure, thermodynamic stabilities as well as vibrational and rotational spectroscopic parameters which could eventually help in their experimental detection. In addition, we have carried out a detailed study of the bonding situations by means of a topological analysis of the electron density in the framework of the Bader's quantum theory of atoms in molecules. The analysis of the relative stabilities and spectroscopic parameters suggests two linear isomers of the neutral [C,H,N,Zn] composition, namely, cyanidehydridezinc HZnCN (1Σ) and hydrideisocyanidezinc HZnNC (1Σ), as possible candidates for experimental detections. For the cationic [C,H,N,Zn]+ composition, the most stable isomers are the ion-molecule complexes arising from the direct interaction of the zinc cation with either the nitrogen or carbon atom of either hydrogen cyanide or hydrogen isocyanide, namely, HCNZn+ (2Σ) and HCNZn+ (2Σ).

  4. Structure and spectroscopic properties of neutral and cationic tetratomic [C,H,N,Zn] isomers: A theoretical study

    International Nuclear Information System (INIS)

    Redondo, Pilar; Largo, Antonio; Vega-Vega, Álvaro; Barrientos, Carmen

    2015-01-01

    The structure and spectroscopic parameters of the most relevant [C,H,N,Zn] isomers have been studied employing high-level quantum chemical methods. For each isomer, we provide predictions for their molecular structure, thermodynamic stabilities as well as vibrational and rotational spectroscopic parameters which could eventually help in their experimental detection. In addition, we have carried out a detailed study of the bonding situations by means of a topological analysis of the electron density in the framework of the Bader’s quantum theory of atoms in molecules. The analysis of the relative stabilities and spectroscopic parameters suggests two linear isomers of the neutral [C,H,N,Zn] composition, namely, cyanidehydridezinc HZnCN ( 1 Σ) and hydrideisocyanidezinc HZnNC ( 1 Σ), as possible candidates for experimental detections. For the cationic [C,H,N,Zn] + composition, the most stable isomers are the ion-molecule complexes arising from the direct interaction of the zinc cation with either the nitrogen or carbon atom of either hydrogen cyanide or hydrogen isocyanide, namely, HCNZn + ( 2 Σ) and HCNZn + ( 2 Σ)

  5. Structure and spectroscopic properties of neutral and cationic tetratomic [C,H,N,Zn] isomers: A theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Redondo, Pilar; Largo, Antonio; Vega-Vega, Álvaro; Barrientos, Carmen, E-mail: cbb@qf.uva.es [Departamento de Química Física y Química Inorgánica, Facultad de Ciencias, Universidad de Valladolid, 47011 Valladolid (Spain)

    2015-05-14

    The structure and spectroscopic parameters of the most relevant [C,H,N,Zn] isomers have been studied employing high-level quantum chemical methods. For each isomer, we provide predictions for their molecular structure, thermodynamic stabilities as well as vibrational and rotational spectroscopic parameters which could eventually help in their experimental detection. In addition, we have carried out a detailed study of the bonding situations by means of a topological analysis of the electron density in the framework of the Bader’s quantum theory of atoms in molecules. The analysis of the relative stabilities and spectroscopic parameters suggests two linear isomers of the neutral [C,H,N,Zn] composition, namely, cyanidehydridezinc HZnCN ({sup 1}Σ) and hydrideisocyanidezinc HZnNC ({sup 1}Σ), as possible candidates for experimental detections. For the cationic [C,H,N,Zn]{sup +} composition, the most stable isomers are the ion-molecule complexes arising from the direct interaction of the zinc cation with either the nitrogen or carbon atom of either hydrogen cyanide or hydrogen isocyanide, namely, HCNZn{sup +} ({sup 2}Σ) and HCNZn{sup +} ({sup 2}Σ)

  6. A Study of Complexation-ability of Neutral Schiff Bases to Some Metal Cations

    Directory of Open Access Journals (Sweden)

    Umit Cakir

    2007-09-01

    Full Text Available The constants of the extraction equilibrium and the distribution fordichloromethane as an organic solvent having low dielectric constant of metal cations withchiral Schiff bases, benzaldehydene-(S-2-amino-3-phenylpropanol (I, o- benzaldehydene-(S-2-hydroxybenzaldehydene-(S-2-amino-3-phenyl-propanol (II,amino-3-methylbutanol (III with anionic dyes [4-(2-pyridylazo-resorcinol mono sodiummonohydrate (NaPar, sodium picrat (NaPic and potassium picrat (KPic] and some heavymetal chlorides were determined at 25 oC. All the ligands have given strongestcomplexation for NaPar. In contrast, similar behaviour for both alkali metal picrates is notapparent in the complexation of corresponding ligands.

  7. Expedient Syntheses of Neutral and Cationic Au(I)–NHC Complexes

    KAUST Repository

    Veenboer, Richard M. P.

    2017-09-08

    The synthesis and isolation of gold(I) precatalysts often requires the generation of several isolable intermediates as well as numerous purification steps. New protocols for the expedient synthesis of neutral [Au(OH)(NHC)] and [Au(CH2COCH3)(NHC)] species from [AuCl(NHC)] or [AuCl(DMS)] precursors bearing a variety of N-heterocyclic carbene (NHC) ligands are presented. These methods can be employed in a telescoping manner for the synthesis of catalytically relevant [Au(NTf2)(NHC)] and [Au(NHC)(NCCH3)][BF4] complexes. These attractive methods are straightforward and practical leading to various complexes in high isolated yields and purity.

  8. Expedient Syntheses of Neutral and Cationic Au(I)–NHC Complexes

    KAUST Repository

    Veenboer, Richard M. P.; Gasperini, Danila; Nahra, Fady; Cordes, David B.; Slawin, Alexandra M. Z.; Cazin, Catherine S. J.; Nolan, Steven P.

    2017-01-01

    The synthesis and isolation of gold(I) precatalysts often requires the generation of several isolable intermediates as well as numerous purification steps. New protocols for the expedient synthesis of neutral [Au(OH)(NHC)] and [Au(CH2COCH3)(NHC)] species from [AuCl(NHC)] or [AuCl(DMS)] precursors bearing a variety of N-heterocyclic carbene (NHC) ligands are presented. These methods can be employed in a telescoping manner for the synthesis of catalytically relevant [Au(NTf2)(NHC)] and [Au(NHC)(NCCH3)][BF4] complexes. These attractive methods are straightforward and practical leading to various complexes in high isolated yields and purity.

  9. Methyl cation affinities of neutral and anionic maingroup-element hydrides: trends across the periodic table and correlation with proton affinities.

    Science.gov (United States)

    Mulder, R Joshua; Guerra, Célia Fonseca; Bickelhaupt, F Matthias

    2010-07-22

    We have computed the methyl cation affinities in the gas phase of archetypal anionic and neutral bases across the periodic table using ZORA-relativistic density functional theory (DFT) at BP86/QZ4P//BP86/TZ2P. The main purpose of this work is to provide the methyl cation affinities (and corresponding entropies) at 298 K of all anionic (XH(n-1)(-)) and neutral bases (XH(n)) constituted by maingroup-element hydrides of groups 14-17 and the noble gases (i.e., group 18) along the periods 2-6. The cation affinity of the bases decreases from H(+) to CH(3)(+). To understand this trend, we have carried out quantitative bond energy decomposition analyses (EDA). Quantitative correlations are established between the MCA and PA values.

  10. Quantum chemical study of the interaction of elemental Hg with small neutral, anionic and cationic Aun (n = 1–6) clusters

    International Nuclear Information System (INIS)

    Siddiqui, Shamoon Ahmad; Bouarissa, Nadir; Rasheed, Tabish; Al-Assiri, M.S.

    2013-01-01

    Graphical abstract: Binding energies as a function of cluster size for Au n Hg, Au n Hg + and Au n Hg − complexes. Highlights: ► Hg adsorption of neutral and charged Au n (n = 1–6) clusters has been discussed. ► Size and charged state of cluster significantly affect the Hg adsorption. ► Transfer of electron mainly found from s orbital of Hg to s orbital of Au. - Abstract: Adsorption of elemental mercury (Hg) on small neutral, cationic and anionic gold clusters (Au n , n = 1–6) has been studied by using the density functional theory (DFT). Results of this investigation show that frontier molecular orbital theory is a useful tool to predict the selectivity of Hg adsorption. It is found that adsorption of Hg on neutral, cationic and anionic Au n (n = 1–6) clusters are thermodynamically favorable. The binding energies of Hg on the cationic Au n clusters are greater than those on the neutral and anionic clusters. Natural bond orbital (NBO) analysis indicates that the flow of electrons in the neutral and charged clusters is mainly due to the s orbitals of Hg and Au. Results of NBO analysis also indicate that the binding energy of Hg with Au n clusters is directly proportional to the charge transfer, i.e. greater is the charge transfer, higher is the binding energy

  11. Neutralization of methyl cation via chemical reactions in low-energy ion-surface collisions with fluorocarbon and hydrocarbon self-assembled monolayer films.

    Science.gov (United States)

    Somogyi, Arpád; Smith, Darrin L; Wysocki, Vicki H; Colorado, Ramon; Lee, T Randall

    2002-10-01

    Low-energy ion-surface collisions of methyl cation at hydrocarbon and fluorocarbon self-assembled monolayer (SAM) surfaces produce extensive neutralization of CH3+. These experimental observations are reported together with the results obtained for ion-surface collisions with the molecular ions of benzene, styrene, 3-fluorobenzonitrile, 1,3,5-triazine, and ammonia on the same surfaces. For comparison, low-energy gas-phase collisions of CD3+ and 3-fluorobenzonitrile molecular ions with neutral n-butane reagent gas were conducted in a triple quadrupole (QQQ) instrument. Relevant MP2 6-31G*//MP2 6-31G* ab initio and thermochemical calculations provide further insight in the neutralization mechanisms of methyl cation. The data suggest that neutralization of methyl cation with hydrocarbon and fluorocarbon SAMs occurs by concerted chemical reactions, i.e., that neutralization of the projectile occurs not only by a direct electron transfer from the surface but also by formation of a neutral molecule. The calculations indicate that the following products can be formed by exothermic processes and without appreciable activation energy: CH4 (formal hydride ion addition) and C2H6 (formal methyl anion addition) from a hydrocarbon surface and CH3F (formal fluoride addition) from a fluorocarbon surface. The results also demonstrate that, in some cases, simple thermochemical calculations cannot be used to predict the energy profiles because relatively large activation energies can be associated with exothermic reactions, as was found for the formation of CH3CF3 (formal addition of trifluoromethyl anion).

  12. G2(+)M study on N-alkylamino cation affinities of neutral main-group element hydrides: trends across the periodic table.

    Science.gov (United States)

    Geng, Song; Wu, Ding-Lu; Yang, Jing; Wei, Xi-Guang; Zhu, Jun; Zhang, Hai-Bo; Ren, Yi; Lau, Kai-Chung

    2014-05-08

    We have made an extensive theoretical exploration of gas-phase N-alkylamino cation affinities (NAAMCA), including amino cation affinities (AMCA) and N-dimethylamino cation affinities (NDMAMCA), of neutral main-group element hydrides of groups 15-17 and periods 2-4 in the periodic table by using the G2(+)M method. Some similarities and differences are found between NAAMCA and the corresponding alkyl cation affinities (ACA) of H(n)X. Our calculations show that the AMCA and NDMAMCA are systematically lower than the corresponding proton affinities (PA) for H(n)X. In general, there is no linear correlation between NAAMCA and PA of H(n)X. Instead, the correlations exist only within the central elements X in period 2, or periods 3-4, which is significantly different from the reasonable correlations between ACA and PA for all H(n)X. NAAMCA (H(n)X) are weaker than NAAMCA (H(n-1)X(-)) by more than 700 kJ/mol and generally stronger than ACA (H(n)X), with three exceptions: H2ONR2(+)(R = H, Me) and HFNH2(+). These new findings can be rationalized by the negative hyperconjugation and Pauli repulsion.

  13. Molecular basis for endotoxin neutralization by amphipathic peptides derived from the alpha-helical cationic core-region of NK-lysin.

    Science.gov (United States)

    Brandenburg, Klaus; Garidel, Patrick; Fukuoka, Satoshi; Howe, Jörg; Koch, Michel H J; Gutsmann, Thomas; Andrä, Jörg

    2010-08-01

    An analysis of the interaction of the NK-lysin derived peptide NK-2 and of analogs thereof with bacterial lipopolysaccharide (LPS, endotoxin) was performed to determine the most important biophysical parameters for an effective LPS neutralization. We used microcalorimetry, FTIR spectroscopy, Zeta potential measurements, and small-angle X-ray scattering to analyze the peptide:LPS binding enthalpy, the accessible LPS surface charge, the fluidity of the LPS hydrocarbon chains, their phase transition enthalpy change, the aggregate structure of LPS, and how these parameters are modulated by the peptides. We conclude that (i) a high peptide:LPS binding affinity, which is facilitated by electrostatic and hydrophobic interactions and which leads to a positive Zeta potential, (ii) the formation of peptide-enriched domains, which destabilize the lipid packing, demonstrated by a drastic decrease of phase transition enthalpy change of LPS, and (iii) the multilamellarization of the LPS aggregate structure are crucial for an effective endotoxin neutralization by cationic peptides.

  14. Fragmentation characteristics of the unstable [CH3 CO][radical sign] radicals generated by neutralization of [CH3CO]+ cations

    Science.gov (United States)

    Hop, C. E. C. A.; Holmes, J. L.

    1991-03-01

    The stability and fragmentation characteristics of [CH3 CO][radical sign] radicals, generated by vertical charge exchange between acetyl cations and permanent gases or metal vapours (He, Xe, NO, Cd, Na and K), were examined mass spectrometrically. Two dissociation reactions were observed, the losses of CH[radical sign]3 and H[radical sign]. The H[radical sign] loss reaction, the higher energy dissociation, became of greater importance as the exothermicity of the charge exchange was increased. Based on the analysis of the kinetic energy releases it was concluded that these decompositions arose from the population of two excited states of the [CH3 CO][radical sign] radical.

  15. Eliminating the Heart from the Curcumin Molecule: Monocarbonyl Curcumin Mimics (MACs)

    Science.gov (United States)

    Shetty, Dinesh; Kim, Yong Joon; Shim, Hyunsuk; Snyder, James P.

    2015-01-01

    Curcumin is a natural product with several thousand years of heritage. Its traditional Asian application to human ailments has been subjected in recent decades to worldwide pharmacological, biochemical and clinical investigations. Curcumin’s Achilles heel lies in its poor aqueous solubility and rapid degradation at pH ~ 7.4. Researchers have sought to unlock curcumin’s assets by chemical manipulation. One class of molecules under scrutiny are the monocarbonyl analogs of curcumin (MACs). A thousand plus such agents have been created and tested primarily against cancer and inflammation. The outcome is clear. In vitro, MACs furnish a 10–20 fold potency gain vs. curcumin for numerous cancer cell lines and cellular proteins. Similarly, MACs have successfully demonstrated better pharmacokinetic (PK) profiles in mice and greater tumor regression in cancer xenografts in vivo than curcumin. The compounds reveal limited toxicity as measured by murine weight gain and histopathological assessment. To our knowledge, MAC members have not yet been monitored in larger animals or humans. However, Phase 1 clinical trials are certainly on the horizon. The present review focuses on the large and evolving body of work in cancer and inflammation, but also covers MAC structural diversity and early discovery for treatment of bacteria, tuberculosis, Alzheimer’s disease and malaria. PMID:25547726

  16. Eliminating the Heart from the Curcumin Molecule: Monocarbonyl Curcumin Mimics (MACs

    Directory of Open Access Journals (Sweden)

    Dinesh Shetty

    2014-12-01

    Full Text Available Curcumin is a natural product with several thousand years of heritage. Its traditional Asian application to human ailments has been subjected in recent decades to worldwide pharmacological, biochemical and clinical investigations. Curcumin’s Achilles heel lies in its poor aqueous solubility and rapid degradation at pH ~ 7.4. Researchers have sought to unlock curcumin’s assets by chemical manipulation. One class of molecules under scrutiny are the monocarbonyl analogs of curcumin (MACs. A thousand plus such agents have been created and tested primarily against cancer and inflammation. The outcome is clear. In vitro, MACs furnish a 10–20 fold potency gain vs. curcumin for numerous cancer cell lines and cellular proteins. Similarly, MACs have successfully demonstrated better pharmacokinetic (PK profiles in mice and greater tumor regression in cancer xenografts in vivo than curcumin. The compounds reveal limited toxicity as measured by murine weight gain and histopathological assessment. To our knowledge, MAC members have not yet been monitored in larger animals or humans. However, Phase 1 clinical trials are certainly on the horizon. The present review focuses on the large and evolving body of work in cancer and inflammation, but also covers MAC structural diversity and early discovery for treatment of bacteria, tuberculosis, Alzheimer’s disease and malaria.

  17. Anticancer effects of monocarbonyl analogs of curcumin: oxidative stress, nuclear translocation and modulation of AP-1 and NF-κB

    Directory of Open Access Journals (Sweden)

    Brian Adams

    2015-01-01

    Full Text Available Purpose: In order to elucidate anticancer effects of monocarbonyl analogs of curcumin (MACs, we have undertaken the present study to obtain information regarding drug targets by using a microarray approach, and to study the cellular localization of EF24 and the activity of two key transcription factors, AP-1 and NF-κB, involved in complex cellular responses of cell survival and death. Methods: Cytotoxic activity of various drugs was evaluated using a Neutral Red Dye assay. Cellular localization of biotinylated EF24 (active and reduced EF24 (inactive was determined using light and confocal microscopy. Measurement of transcription factor binding was carried out using Transfactor ELISA kits (BD Clontech, Palo Alto, CA. Gene microarray processing was performed at Expression Analysis, Inc (Durham, NC using Affymetrix Human U133A Gene Chips.Results: In this study, we demonstrated that EF24 and UBS109 exhibit much more potent cytotoxic activity against pancreatic cancer than the current standard chemotherapeutic agent gemcitabine. EF24, rapidly localizes to the cell nucleus. The compound modulates the DNA binding activity of NF-κB and AP-1 in MDA-MB-231 human breast cancer cells and DU-145 human prostate cancer cells. Immunohistochemical studies utilizing biotinylated-EF24 and chemically-reduced EF24 show that the unsaturated compound and biotinylated EF24, but not reduced EF24, translocates to the nucleus within 30 minutes after the addition of drug. Through a gene microarray study, EF24 is shown to affect genes directly involved in cytoprotection, tumor growth, angiogenesis, metastasis and apoptosis. Conclusion: EF24 and UBS109 warrant further investigation for development of pancreatic cancer therapy. The dualistic modulations of gene expression may be a manifestation of the cell responses for survival against oxidative stress by EF24. However, the cytotoxic action of EF24 ultimately prevails to kill the cells.

  18. On the origin of bonding and vibrational frequency shifts for CO adsorbed on neutral, cationic and anionic gold clusters

    International Nuclear Information System (INIS)

    Bagus, P S; Pacchioni, G

    2008-01-01

    We report a detailed analysis of the electronic mechanisms which determine the bond strength and the vibrational frequency of CO molecules adsorbed on neutral or charged gold nanoparticles. To this end we have considered a simple cluster model, Au 5 CO q (q = +1, 0, -1), and decomposed the Au-CO interaction energy into the sum of various contributions according to a Constrained Space Orbital Variation approach. While the adsorption energy is relatively insensitive to the value of q, the C-O stretch frequency, ω e (CO), changes substantially, and allows the use of this molecule as a direct probe of the gold oxidation state. The results show that two major terms contribute to the red or blue shift of ω e (CO) as a function of q: the interaction with the electric field associated to the charged nanoparticle (Stark effect) and the Au → CO Φ back donation. The CO → Au σ donation is about half as important as the Φ back-donation and all other terms are much less important

  19. Formation of neutral and charged gold carbonyls on highly facetted gold nanostructures

    Science.gov (United States)

    Chau, Thoi-Dai; Visart de Bocarmé, Thierry; Kruse, Norbert; Wang, Richard L. C.; Kreuzer, Hans Jürgen

    2003-12-01

    We show that gold mono- and di-carbonyls are formed on gold field emitter tips during interaction with carbon monoxide gas at room temperature and in the presence of high electrostatic fields. The experiments are done in a time-of-flight atom probe to obtain mass spectra. The yield of monocarbonyl cations is about twice that of di-carbonyl ions. Density functional theory calculations are reported that explain the field stabilization of adsorbed carbonyls and the desorption yield of their cations.

  20. Actinide cation-cation complexes

    International Nuclear Information System (INIS)

    Stoyer, N.J.; Seaborg, G.T.

    1994-12-01

    The +5 oxidation state of U, Np, Pu, and Am is a linear dioxo cation (AnO 2 + ) with a formal charge of +1. These cations form complexes with a variety of other cations, including actinide cations. Other oxidation states of actinides do not form these cation-cation complexes with any cation other than AnO 2 + ; therefore, cation-cation complexes indicate something unique about AnO 2 + cations compared to actinide cations in general. The first cation-cation complex, NpO 2 + ·UO 2 2+ , was reported by Sullivan, Hindman, and Zielen in 1961. Of the four actinides that form AnO 2 + species, the cation-cation complexes of NpO 2 + have been studied most extensively while the other actinides have not. The only PuO 2 + cation-cation complexes that have been studied are with Fe 3+ and Cr 3+ and neither one has had its equilibrium constant measured. Actinides have small molar absorptivities and cation-cation complexes have small equilibrium constants; therefore, to overcome these obstacles a sensitive technique is required. Spectroscopic techniques are used most often to study cation-cation complexes. Laser-Induced Photacoustic Spectroscopy equilibrium constants for the complexes NpO 2 + ·UO 2 2+ , NpO 2 + ·Th 4+ , PuO 2 + ·UO 2 2+ , and PuO 2 + ·Th 4+ at an ionic strength of 6 M using LIPAS are 2.4 ± 0.2, 1.8 ± 0.9, 2.2 ± 1.5, and ∼0.8 M -1

  1. Heterocyclic cyclohexanone monocarbonyl analogs of curcumin can inhibit the activity of ATP-binding cassette transporters in cancer multidrug resistance.

    Science.gov (United States)

    Revalde, Jezrael L; Li, Yan; Hawkins, Bill C; Rosengren, Rhonda J; Paxton, James W

    2015-02-01

    Curcumin (CUR) is a phytochemical that inhibits the xenobiotic ABC efflux transporters implicated in cancer multidrug resistance (MDR), such as P-glycoprotein (P-gp), breast cancer resistance protein (BCRP) and multidrug resistance-associated proteins 1 and 5 (MRP1 and MRP5). The use of CUR in the clinic however, is complicated by its instability and poor pharmacokinetic profile. Monocarbonyl analogs of CUR (MACs) are compounds without CUR's unstable β-diketone moiety and were reported to have improved stability and in vivo disposition. Whether the MACs can be used as MDR reversal agents is less clear, as the absence of a β-diketone may negatively impact transporter inhibition. In this study, we investigated 23 heterocyclic cyclohexanone MACs for inhibitory effects against P-gp, BCRP, MRP1 and MRP5. Using flow cytometry and resistance reversal assays, we found that many of these compounds inhibited the transport activity of the ABC transporters investigated, often with much greater potency than CUR. Overall the analogs were most effective at inhibiting BCRP and we identified three compounds, A12 (2,6-bis((E)-2,5-dimethoxy-benzylidene)cyclohexanone), A13 (2,6-bis((E)-4-hydroxyl-3-methoxybenzylidene)-cyclohexanone) and B11 (3,5-bis((E)-2-fluoro-4,5-dimethoxybenzylidene)-1-methylpiperidin-4-one), as the most promising BCRP inhibitors. These compounds inhibited BCRP activity in a non-cell line, non-substrate-specific manner. Their inhibition occurred by direct transporter interaction rather than modulating protein or cell surface expression. From these results, we concluded that MACs, such as the heterocyclic cyclohexanone analogs in this study, also have potential as MDR reversal agents and may be superior alternatives to the unstable parent compound, CUR. Copyright © 2014 Elsevier Inc. All rights reserved.

  2. Letter: OCCO*+, NNCO*+ and NNNN*+ radical cations.

    Science.gov (United States)

    Flammang, R; Srinivas, R; Nguyen, M T; Gerbaux, P

    2007-01-01

    Chemical ionization of a mixture of nitrogen and carbon monoxide produces three stable isobaric species at m/z 56: OCCO, OCNN and NNNN radical cations. Separated at increased resolution, these ions are readily identified by collisional activation. Neutralization-reionization experiments performed on two different mass spectrometers have not allowed the detection of any recovery signals for the corresponding neutrals.

  3. Selective Generation of the Radical Cation Isomers [CH3CN](•+) and [CH2CNH](•+) via VUV Photoionization of Different Neutral Precursors and Their Reactivity with C2H4.

    Science.gov (United States)

    Polášek, Miroslav; Zins, Emilie-Laure; Alcaraz, Christian; Žabka, Ján; Křížová, Věra; Giacomozzi, Linda; Tosi, Paolo; Ascenzi, Daniela

    2016-07-14

    Experimental and theoretical studies have been carried out to demonstrate the selective generation of two different C2H3N(+) isomers, namely, the acetonitrile [CH3CN](•+) and the ketenimine [CH2CNH](•+) radical cations. Photoionization and dissociative photoionization experiments from different neutral precursors (acetonitrile and butanenitrile) have been performed using vacuum ultraviolet (VUV) synchrotron radiation in the 10-15 eV energy range, delivered by the DESIRS beamline at the SOLEIL storage ring. For butanenitrile (CH3CH2CH2CN) an experimental ionization threshold of 11.29 ± 0.05 eV is obtained, whereas the appearance energy for the formation of [CH2CNH](•+) fragments is 11.52 ± 0.05 eV. Experimental findings are fully supported by theoretical calculations at the G4 level of theory (ZPVE corrected energies at 0 K), giving a value of 11.33 eV for the adiabatic ionization energy of butanenitrile and an exothermicity of 0.49 for fragmentation into [CH2CNH](•+) plus C2H4, hampered by an energy barrier of 0.29 eV. The energy difference between [CH3CN](•+) and [CH2CNH](•+) is 2.28 eV (with the latter being the lowest energy isomer), and the isomerization barrier is 0.84 eV. Reactive monitoring experiments of the [CH3CN](•+) and [CH2CNH](•+) isomers with C2H4 have been performed using the CERISES guided ion beam tandem mass spectrometer and exploiting the selectivity of ethylene that gives exothermic charge exchange and proton transfer reactions with [CH3CN](•+) but not with [CH2CNH](•+) isomers. In addition, minor reactive channels are observed leading to the formation of new C-C bonds upon reaction of [CH3CN](•+) with C2H4, and their astrochemical implications are briefly discussed.

  4. phenanthrolinium cation

    African Journals Online (AJOL)

    KEY WORDS: Phenanthroline, H-bonding, X-ray structure, π- π stacking .... Density(calc) g/cm3. 1.281. 1.507. 1.167. Absorption coefficient mm-1. 0.260 ... in Figure 3, where an unprotonated neutral molecule co-crystallizes along with the.

  5. Comparative study of the antioxidant properties of monocarbonyl curcumin analogues C66 and B2BrBC in isoproteranol induced cardiac damage.

    Science.gov (United States)

    Hadzi-Petrushev, Nikola; Bogdanov, Jane; Krajoska, Jovanka; Ilievska, Jovana; Bogdanova-Popov, Biljana; Gjorgievska, Elizabeta; Mitrokhin, Vadim; Sopi, Ramadan; Gagov, Hristo; Kamkin, Andre; Mladenov, Mitko

    2018-03-15

    To test the antioxidant properties of the newly synthesized (2E,6E)-2,6-bis(2-bromobenzylidene)cyclohexanone (B2BrBC) in parallel with C66 in rats with cardiac hypertrophy. The protective effects of both C66 and B2BrBC against oxidative stress in rats with cardiac hypertrophy, was studied by evaluating the activity of antioxidant enzymes, the relationship between the ratio of the activities of the antioxidant enzymes R = SOD/(GPx + CAT) and levels of thiols and lipid peroxidation in the heart. In order to gain better understanding of the antioxidant properties of the studied compounds, computational methods were utilized. The properties of selected structurally related derivatives were obtained on optimized geometries for ground states, using semi-empirical PM3 quantum mechanical calculations. The ratio R shows disequilibrium in rats with induced hypertrophy (p antioxidant. The obtained results indicated that the antioxidant ability of B2BrBC is positively associated with the catalytic SOD and GPx activities expressed through preserved t-SH levels. It seems plausible that for a compound to exhibit antioxidant activity, as most of the 2,6-bis(benzylidene)cyclohexanones do, they should be good electron donors. Understanding the relationship between cardiac hypertrophy induced oxidative injuries and supporters of endogenous reparatory machinery will help in establishing the beneficial role of adequate antioxidant supplementation. In this study reliable data on the preventive effects of newly synthesized symmetric monocarbonyl curcumin analogue B2BrBC and its role in the prevention of oxidative injuries on three levels (enzymatic, protein and lipid), in the heart hypertrophic onset, were obtained. Copyright © 2018 Elsevier Inc. All rights reserved.

  6. Complexing and analysis of cation selectivity of neutral phosphoryl-containing tripodaud of tris((0-diphenyl-phosphinoylmethyl)phenoxyethyl)amine to lithium sodium and potassium, in acetonitrile. Lithium selectivity and polymeclear compleses

    International Nuclear Information System (INIS)

    Baulin, V.E.; Solov'ev, V.P.; Strakhova, N.N.; Kazachenko, V.P.

    1996-01-01

    A new phosphoryl-containing tripodand-tris-[(0-diphenyl-phosphinoylmethyl)phenoxyethyl] amine-was synthesized. Constants of stability, enthalpy and entropy of reactions of tripodond complexing with lithium, sodium, potassium thiocyanates in acetonitrile at 298 k were determined. Investigation of complexing by the methods of calorimetry, 7 Li and 23 Na NMR, mass-spectrometry enabled to conclude that ligand formed polynuclear complexes with lithium thiocyanate of 2/1 and 3/1 composition along with 1/1 complex. High selectivity of podand to lithium cation in acetonitrile was conditioned by formation of polynuclear complexes. Refs. 29, figs. 3

  7. Synthesis and optimization of novel allylated mono-carbonyl analogs of curcumin (MACs) act as potent anti-inflammatory agents against LPS-induced acute lung injury (ALI) in rats.

    Science.gov (United States)

    Zhu, Heping; Xu, Tingting; Qiu, Chenyu; Wu, Beibei; Zhang, Yali; Chen, Lingfeng; Xia, Qinqin; Li, Chenglong; Zhou, Bin; Liu, Zhiguo; Liang, Guang

    2016-10-04

    A series of novel symmetric and asymmetric allylated mono-carbonyl analogs of curcumin (MACs) were synthesized using an appropriate synthetic route and evaluated experimentally thru the LPS-induced expression of TNF-α and IL-6. Most of the obtained compounds exhibited improved water solubility as a hydrochloride salt compared to lead molecule 8f. The most active compound 7a was effective in reducing the Wet/Dry ratio in the lungs and protein concentration in bronchoalveolar lavage fluid. Meanwhile, 7a also inhibited mRNA expression of several inflammatory cytokines, including TNF-α, IL-6, IL-1β, and VCAM-1, in Beas-2B cells after Lipopolysaccharide (LPS) challenge. These results suggest that 7a could be therapeutically beneficial for use as an anti-inflammatory agent in the clinical treatment of acute lung injury (ALI). Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  8. Effects of metallic cations in the beryl flotation

    International Nuclear Information System (INIS)

    Lima Leonel, C.M. de; Peres, A.E.C.

    1984-01-01

    The beryl zeta potential in microelectrophoretic cell is studied in the presence of neutral electrolyte, cations of calcium, magnesium and iron. The petroleum sulfonate is used how collector in Hallimond tube. Hydroxy complex of metallic cations seems activate the ore and precipitates of colloidal metallic hidroxies seems lower him when added to the mixture. (M.A.C.) [pt

  9. Base Cation Leaching From the Canopy of a Rubber ( Hevea ...

    African Journals Online (AJOL)

    Base cations are essential to the sustainability of forest ecosystems. They are important for neutralizing the acidifying effects of atmospheric deposition. There is the need for in-depth understanding of base cation depletion and leaching from forest canopy. This is important particularly due to the increasing acidification and ...

  10. Neutral currents

    International Nuclear Information System (INIS)

    Paschos, E.A.

    1977-01-01

    It is stated that over the past few years considerable progress has been made in the field of weak interactions. The existence of neutral currents involving leptons and hadrons has been established and some of the questions concerning their detailed structure have been answered. This imposes constraints on the gauge theories and has eliminated large classes of models. New questions have also been raised, one of which concerns the conservation laws obeyed by neutral currents. The wide range of investigations is impressive and is expected to continue with new results from particle, nuclear, and atomic physics. Headings include - various aspects of a gauge theory (choice of group, the symmetry breaking scheme, representation assignments for fermion fields); space-time structure; isospin structure; leptonic neutral currents; and atomic experiments. (U.K.)

  11. Neutral currents

    International Nuclear Information System (INIS)

    Aubert, B.

    1994-11-01

    The evidence for the existence of weak neutral current has been a very controverted topics in the early 1970's, as well as the muon did in the 1930's. The history is very rich considering the evolution of the experimental techniques in high energy particle physics. The history of the discovery and the study of weak neutral current is reviewed. Later the quest of the intermediate vector boson continues with the decision of the community to build a large proton antiproton collider. (K.A.). 14 refs., 1 fig

  12. Isomerization of propargyl cation to cyclopropenyl cation ...

    Indian Academy of Sciences (India)

    step) for isomeri- zation of the linear propargyl cation to ..... C3, C4 and C5. The ZPE corrections in each case are derived from the. B3LYP calculations. ..... the converse of which gives the relative capacity of the. LPD's to stabilize TS6 with respect ...

  13. Neutral anion receptors: design and application

    NARCIS (Netherlands)

    Antonisse, M.M.G.; Reinhoudt, David

    1998-01-01

    After the development of synthetic cation receptors in the late 1960s, only in the past decade has work started on the development of synthetic neutral anion receptors. Combination and preorganization of different anion binding groups, like amides, urea moieties, or Lewis acidic metal centers lead

  14. Cation exchange properties of zeolites in hyper alkaline aqueous media.

    Science.gov (United States)

    Van Tendeloo, Leen; de Blochouse, Benny; Dom, Dirk; Vancluysen, Jacqueline; Snellings, Ruben; Martens, Johan A; Kirschhock, Christine E A; Maes, André; Breynaert, Eric

    2015-02-03

    Construction of multibarrier concrete based waste disposal sites and management of alkaline mine drainage water requires cation exchangers combining excellent sorption properties with a high stability and predictable performance in hyper alkaline media. Though highly selective organic cation exchange resins have been developed for most pollutants, they can serve as a growth medium for bacterial proliferation, impairing their long-term stability and introducing unpredictable parameters into the evolution of the system. Zeolites represent a family of inorganic cation exchangers, which naturally occur in hyper alkaline conditions and cannot serve as an electron donor or carbon source for microbial proliferation. Despite their successful application as industrial cation exchangers under near neutral conditions, their performance in hyper alkaline, saline water remains highly undocumented. Using Cs(+) as a benchmark element, this study aims to assess the long-term cation exchange performance of zeolites in concrete derived aqueous solutions. Comparison of their exchange properties in alkaline media with data obtained in near neutral solutions demonstrated that the cation exchange selectivity remains unaffected by the increased hydroxyl concentration; the cation exchange capacity did however show an unexpected increase in hyper alkaline media.

  15. Cation Exchange Water Softeners

    Science.gov (United States)

    WaterSense released a notice of intent to develop a specification for cation exchange water softeners. The program has made the decision not to move forward with a spec at this time, but is making this information available.

  16. Structure and Intramolecular Proton Transfer of Alanine Radical Cations

    International Nuclear Information System (INIS)

    Lee, Gab Yong

    2012-01-01

    The structures of the four lowest alanine conformers, along with their radical cations and the effect of ionization on the intramolecular proton transfer process, are studied using the density functional theory and MP2 method. The energy order of the radical cations of alanine differs from that of the corresponding neutral conformers due to changes in the basicity of the NH 2 group upon ionization. Ionization favors the intramolecular proton transfer process, leading to a proton-transferred radical-cation structure, [NH 3 + -CHCH 3 -COO·], which contrasts with the fact that a proton-transferred zwitterionic conformer is not stable for a neutral alanine in the gas phase. The energy barrier during the proton transfer process is calculated to be about 6 kcal/mol

  17. Cation radicals of xanthophylls.

    Science.gov (United States)

    Galinato, Mary Grace I; Niedzwiedzki, Dariusz; Deal, Cailin; Birge, Robert R; Frank, Harry A

    2007-10-01

    Carotenes and xanthophylls are well known to act as electron donors in redox processes. This ability is thought to be associated with the inhibition of oxidative reactions in reaction centers and light-harvesting pigment-protein complexes of photosystem II (PSII). In this work, cation radicals of neoxanthin, violaxanthin, lutein, zeaxanthin, beta-cryptoxanthin, beta-carotene, and lycopene were generated in solution using ferric chloride as an oxidant and then studied by absorption spectroscopy. The investigation provides a view toward understanding the molecular features that determine the spectral properties of cation radicals of carotenoids. The absorption spectral data reveal a shift to longer wavelength with increasing pi-chain length. However, zeaxanthin and beta-cryptoxanthin exhibit cation radical spectra blue-shifted compared to that of beta-carotene, despite all of these molecules having 11 conjugated carbon-carbon double bonds. CIS molecular orbital theory quantum computations interpret this effect as due to the hydroxyl groups in the terminal rings selectively stabilizing the highest occupied molecular orbitals of preferentially populated s-trans-isomers. The data are expected to be useful in the analysis of spectral results from PSII pigment-protein complexes seeking to understand the role of carotene and xanthophyll cation radicals in regulating excited state energy flow, in protecting PSII reaction centers against photoinhibition, and in dissipating excess light energy absorbed by photosynthetic organisms but not used for photosynthesis.

  18. Identifi cation of Sectarianism

    Directory of Open Access Journals (Sweden)

    Martinovich Vladimir

    2016-03-01

    Full Text Available «New religious movements and society» is traditionally one of the most sophisticated topics in the area of new religions studies. Its problem field is so huge that up to now by far not all important research themes where even touched by scientists from all over the world. The problem of the process of the identification of sectarianism by diff erent societal institutions is one of such untouched themes that is taken as the main subject of this article. This process by itself is an inseparable part of the every societal deliberate reaction to the very existence of unconventional religiosity, its unstructured and mainly structured types. The focal point of the article is step-by-step analysis of the general structure elements of the process of the identification of sectarianism without any reference to the specific time and place of its flow. Special attention is paid to the analysis of the subjects of the identification of sectarianism, to the criteria for religious groups to be qualified as new religious movements, and to the specific features of the process of documents filtration. The causes of selective perception of sectarianism are disclosed. Some main consequences and unpredictable outcomes of the process of the identification of sectarianism are described.

  19. Water absorption in neutralized Nafion membranes

    International Nuclear Information System (INIS)

    Rodmacq, B.; Roche, E.; Pineri, M.; Escoubez, M.; Duplessix, R.; Eisenberg, A.

    1979-01-01

    In this paper some results are reported about the interactions between water and Nafion neutralized with different cations. The energy of water absorption have been measured in the whole range of relative humidity pressures. Moessbauer spectra permit to get information about the change of environment of the iron atoms during the hydration. Small angle neutron and X ray scattering experiments have then been performed to define a possible phase segregation. From these results a model of clustering in the Nafion membranes is proposed. The neutralized Nafion samples have been obtained by soaking the acid samples in solutions containing the different salts

  20. Cation transport in isomeric pentanes

    International Nuclear Information System (INIS)

    Gyoergy, Istvan; Gee, Norman; Freeman, G.R.

    1985-01-01

    The cation mobility μsub(+) is measured in n-pentane, isopentane, neo-pentane, and mixtures of n- and neo-pentane over conditions from the normal liquid, through the critical fluid, to the low density gas. Most of the liquid data correlate with the reduced temperature T/Tsub(c). The T/Tsub(c) reflects free volume and viscosity changes. Comparison is made to neutral molecule diffusion. The transition from viscosity control of mobility in the liquid to density control in the dilute gas occurs over the reduced viscosity region 3 > eta/etasub(c) > 0.6, which corresponds to the reduced density region 1.9 > eta/etasub(c) > 0.5. In the saturated gas etaμsub(+) is similar in all pentanes, but iso- approximately> n- > neo-pentane. At constant density dμsub(+)/dT >= 0 for gases. The average gas nμsub(+) is similar in all pentanes, but iso- approximately> n- > neo-pentane. At constant density dμsub(+)/dT >= 0 for gases. The average momentum transfer cross sections in the n-/neo-pentane mixtures are similar to those in neo-pentane at low T but similar to those in n-pentane at high T. The present findings are combined with previous electron mobility data in addressing the effect of hydrocarbon molecular (external) shape on the electric breakdown strength of gases

  1. Disposal of heavy metal cations in aqueous media by adsorption on coal to Ghazni

    Directory of Open Access Journals (Sweden)

    О.М. Заславський

    2008-03-01

    Full Text Available  Adsorption of Pb and Cu cations and their mixture on the surface of modified and non-modified anti-gas coal trough different time intervals have been studied. The maximum adsorption capacity of coal relative to each cations have been determined. Absence  of concurrence between cations of Pb and Cu during adsorption from mixture is explained by difference of  types of their interaction with coal surface. The high effectiveness and perspectivities of application of anti-gas coal for neutralization of heavy metal cations in aqueous solution was shown.

  2. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism.

    Science.gov (United States)

    Boughlala, Zakaria; Fonseca Guerra, Célia; Bickelhaupt, F Matthias

    2016-06-01

    We have analyzed the structure and bonding of gas-phase Cl-X and [HCl-X](+) complexes for X(+)= H(+), CH3 (+), Li(+), and Na(+), using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl(-) and HCl for the various cations. The Cl-X bond becomes longer and weaker along X(+) = H(+), CH3 (+), Li(+), and Na(+). Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence of solvent) alkali metal cation affinities (AMCA) and how this compares with and differs from those of the proton affinity (PA) and methyl cation affinity (MCA). Our analyses are based on Kohn-Sham molecular orbital (KS-MO) theory in combination with a quantitative energy decomposition analysis (EDA) that pinpoints the importance of the different features in the bonding mechanism. Orbital overlap appears to play an important role in determining the trend in cation affinities.

  3. Chemical conditions of the Japanese neutral geothermal reservoirs

    International Nuclear Information System (INIS)

    Chiba, H.

    1991-01-01

    The aqueous speciation were calculated for fluids of seven Japanese geothermal systems. The aqueous composition as well as CO 2 partial pressure of fluid in neutral pH geothermal reservoir are controlled by silicate, calcite and anhydrite minerals. The chemical composition of neutral pH geothermal reservoir can be predictable if two parameters (e.g. temperature and one of the cation activities) are provided. (author)

  4. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism

    OpenAIRE

    Boughlala, Z.; Guerra, C.F.; Bickelhaupt, F.M.

    2016-01-01

    Abstract We have analyzed the structure and bonding of gas?phase Cl?X and [HCl?X]+ complexes for X+=?H+, CH3 +, Li+, and Na+, using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl? and HCl for the various cations. The Cl?X bond becomes longer and weaker along X+?=?H+, CH3 +, Li+, and Na+. Our main purpose is to understand the heterolytic bonding mechanism behind the intrinsic (i.e., in the absence ...

  5. Role of distonic dimer radical cations in the radiation-induced polymerisation of vinyl ethers

    International Nuclear Information System (INIS)

    Naumov, Sergej; Janovsky, Igor; Knolle, Wolfgang; Mehnert, Reiner

    2005-01-01

    The experimental low-temperature EPR results and the quantum chemical calculations suggest that dimer radical cations of cyclic and aliphatic vinyl ethers (VE) plays a key role in starting of radiation-induced polymerisation. The main species observed at high 2,3-dihydrofuran (DHF), 2,3-dihydropyran (DHP) and VE concentration is the dimer radical cation. In the case of cyclic VE the dimer radical cation transforms through H-abstraction from neutral molecule into a carbocation and radical, which could start both cationic and free-radical polymerisation. However, in the case of aliphatic VE no further reactive species, which could start polymerisation, were observed. This is caused (in agreement with experiment and quantum chemical calculations) by the very high stability of dimer radical cation and calculated endothermity of H-abstraction reaction by dimer radical cation from monomer

  6. Structure and dynamics of olefin radical cation aggregates. Time-resolved fluorescence detected magnetic resonance

    International Nuclear Information System (INIS)

    Desrosiers, M.F.; Trifunac, A.D.

    1986-01-01

    The time-resolved EPR spectra and thus the structure and dynamics of transient hydrocarbon radical cations are obtained by the pulse radiolysis-fluorescence detected magnetic resonance (FDMR) technique. Here the authors report the observation of short-lived radical cations from olefins. FDMR-EPR spectra of radical cations from tetramethylethylene and cyclohexadiene are illustrated. The olefin radical cations, FDMR spectra are concentration-dependent, since dimerization with neutral molecules takes place at higher (>10 -2 M) olefin concentration. Rate constants for the dimerization reaction are derived and the effect of solvent viscosity on aggregate formation is demonstrated. By monitoring the further reactions of dimer cations the authors have obtained EPR evidence for previously unobserved higher-order (multimer) radical cation aggregates of olefins. 16 references, 5 figures

  7. Neutral Buoyancy Laboratory (NBL)

    Data.gov (United States)

    Federal Laboratory Consortium — The Neutral Buoyancy Laboratory (NBL) is an astronaut training facility and neutral buoyancy pool operated by NASA and located at the Sonny Carter Training Facility,...

  8. The effect of organic acids on base cation leaching from the forest floor under six North American tree species

    NARCIS (Netherlands)

    Dijkstra, F.A.; Geibe, C.; Holmstrom, S.; Lundstrom, U.S.; Breemen, van N.

    2001-01-01

    Organic acidity and its degree of neutralization in the forest floor can have large consequences for base cation leaching under different tree species. We investigated the effect of organic acids on base cation leaching from the forest floor under six common North American tree species. Forest floor

  9. Sorption by cation exchange

    International Nuclear Information System (INIS)

    Bradbury, M.H.; Baeyens, B.

    1994-04-01

    A procedure for introducing exchange into geochemical/surface complexation codes is described. Beginning with selectivity coefficients, K c , defined in terms of equivalent fractional ion occupancies, a general expression for the molar based exchange code input parameters, K ex , is derived. In natural systems the uptake of nuclides onto complex sorbents often occurs by more than one mechanism. The incorporation of cation exchange and surface complexation into a geochemical code therefore enables sorption by both mechanisms to be calculated simultaneously. The code and model concepts are tested against sets of experimental data from widely different sorption studies. A proposal is made to set up a data base of selectivity coefficients. Such a data base would form part of a more general one consisting of sorption mechanism specific parameters to be used in conjunction with geochemical/sorption codes to model and predict sorption. (author) 6 figs., 6 tabs., 26 refs

  10. Study of neutral particles

    International Nuclear Information System (INIS)

    Bartel, W.; Bulos, F.; Eisner, A.

    1975-01-01

    The range of physics problems for which a detector emphasizing neutrals is most suitable is discussed. The primary goals are the all neutrals cross section, sigma/sub o/ (e + e - → neutrals), the characterization of the neutral energy in multi-hadronic events, the search for monoenergetic photons, and good sensitivity in the difficult region of low energy photons. Those features of multi-hadronic events which are most relevant to a neutral detector were calculated using a jet model with parameters extrapolated from SPEAR energies. These distributions are presented and discussed

  11. Vibrational Spectroscopy of Cation and Anion Channelrhodopsins

    Science.gov (United States)

    Yi, Adrian S.

    Optogenetics is a technique to control and monitor cell activity with light by expression of specific microbial rhodopsins. Cation channelrhodopsins (CCRs) and anion channelrhodopsins (ACRs) have been demonstrated to activate and silence cell activity, respectively. In this dissertation, the molecular mechanisms of two channelrhodopsins are studied: a CCR from Chlamydomonas augustae (CaChR1) and an ACR from Guillardia theta (GtACR1). The recently discovered GtACR1is especially interesting, as it achieves neural silencing with 1/1000th of the light intensity compared to previous microbial rhodopsin silencing ion pumps. Static and time-resolved resonance Raman, FTIR difference, and UV-visible spectroscopies were utilized in addition to various biochemical and genetic techniques to explore the molecular mechanisms of these channelrhodopsins. In CaChR1, Glu169 and Asp299 residues are located nearby the Schiff base (SB) similar to the homologous residues Asp85 and Asp212, which exist in an ionized state in unphotolyzed bacteriorhodopsin (BR) and play a key role in proton pumping. We observe significant changes in the protonation states of the SB, Glu169, and Asp299 of CaChR1 leading up to the open-channel P2 state, where all three groups exist in a charge neutral state. This unusual charge neutrality along with the position of these groups in the CaChR1 ion channel suggests that charge neutrality plays an important role in cation gating and selectivity in these low efficiency CCRs. Significant differences exist in the photocycle and protonation/hydrogen bonding states of key residues inGtACR1compared to BR and CaChR1. Resonance Raman studies reveal that in the unphotolyzed state of GtACR1, residues Glu68, Ser97 (BR Asp85 homolog), and Asp234 (BR Asp212 homolog) located near the SB exist in charge neutral states. Furthermore, upon K formation, these residues do not change their protonation states. At room temperature, a slow decay of the red-shifted K intermediate is

  12. Basic exchangeable cations in Finnish mineral soils

    Directory of Open Access Journals (Sweden)

    Armi Kaila

    1972-09-01

    Full Text Available The content of exchangeable Ca, Mg, K and Na replaced by neutral ammonium acetate was determined in 470 samples of mineral soils from various parts of Finland, except from Lapland. The amount of all these cations tended to increase with an increase in the clay content, but variation within each textural class was large, and the ranges usually overlapped those of the other classes. The higher acidity of virgin surface soils was connected with a lower average degree of saturation by Ca as compared with the corresponding textural classes of cultivated soils. No significant difference in the respective contents of other cations was detected. The samples of various textural groups from deeper layers were usually poorer in exchangeable Ca and K than the corresponding groups of plough layer. The mean content of exchangeable Mg was equal or even higher in the samples from deeper layers than in the samples from plough layer, except in the group of sand soils. The percentage of Mg of the effective CEC increased, as an average, from 9 in the sand and fine sand soils of plough layer to 30 in the heavy clay soils; in the heavy clay soils from deeper layers its mean value was 38 ± 4 %. In the samples of plough layer, the mean ratio of Ca to Mg in sand and fine sand soils was about 9, in silt and loam soils about 6, in the coarser clay soils about 4, and in heavy clay about 2.

  13. Reactions of the radical cations of aliphatic aldehydes in freon matrices

    International Nuclear Information System (INIS)

    Belevskij, V.N.; Belopushkin, S.I.; Feldman, V.I.

    1985-01-01

    ESR spectra of γ-irradiated solutions of acetic and propionic aldehydes in freon-11 and freon-113 affected by aldehyde concentration, temperature, and the action of light were studied. It is shown that the radical cations are converted into neutral radicals, and the cations CHsub(3)CHsub(2)CHOsup(+). are converted to RCO and CHsub(3)CHCHO due to ion-molecular reactions of proton transfer of hydrogen atom transfer. (author)

  14. Electrospray ionization tandem mass spectrometry of ammonium cationized polyethers.

    Science.gov (United States)

    Nasioudis, Andreas; Heeren, Ron M A; van Doormalen, Irene; de Wijs-Rot, Nicolette; van den Brink, Oscar F

    2011-05-01

    Quaternary ammonium salts (Quats) and amines are known to facilitate the MS analysis of high molar mass polyethers by forming low charge state adduct ions. The formation, stability, and behavior upon collision-induced dissociation (CID) of adduct ions of polyethers with a variety of Quats and amines were studied by electrospray ionization quadrupole time-of-flight, quadrupole ion trap, and linear ion trap tandem mass spectrometry (MS/MS). The linear ion trap instrument was part of an Orbitrap hybrid mass spectrometer that allowed accurate mass MS/MS measurements. The Quats and amines studied were of different degree of substitution, structure, and size. The stability of the adduct ions was related to the structure of the cation, especially the amine's degree of substitution. CID of singly/doubly charged primary and tertiary ammonium cationized polymers resulted in the neutral loss of the amine followed by fragmentation of the protonated product ions. The latter reveals information about the monomer unit, polymer sequence, and endgroup structure. In addition, the detection of product ions retaining the ammonium ion was observed. The predominant process in the CID of singly charged quaternary ammonium cationized polymers was cation detachment, whereas their doubly charged adduct ions provided the same information as the primary and tertiary ammonium cationized adduct ions. This study shows the potential of specific amines as tools for the structural elucidation of high molar mass polyethers. © American Society for Mass Spectrometry, 2011

  15. Cationic polymerization of styrene by means of pulse radiolysis

    International Nuclear Information System (INIS)

    Egusa, S.; Arai, S.; Kira, A.; Imamura, M.; Tabata, Y.

    1977-01-01

    The radiation-induced cationic polymerization of styrene has been studied by microsecond pulse radiolysis. It was possible to observe absorption bands of a monomer cation radical (St. + ) at 630 nm and at 350 nm in a mixture of isopentane and n-butyl chloride at - 165 0 C. Three absorption bands, around 1600 nm, at 600 nm and at 450 nm, grew in parallel with the decay of St. + after pulse. The 1600-nm and 600-nm bands were assigned to an associated dimer cation radical (St 2 . + ), and the 450-nm band to a bonded dimer cation radical (St-St. + ) by comparison of absorption spectra of α-methylstyrene, 1,2-dihydronaphthalene and trans-β-methylstyrene. The kinetic behaviour of these species suggests that St-St. + and a part of St 2 . + are formed by the reaction of St. + with a styrene monomer, and the rest of St 2 . + may be formed by positive charge transfer from a solvent cation radical to an auto-associated neutral dimer of styrene. A long-lived absorption band at 340 nm grew with the decay of St-St. + . This band is considered due to a growing polymer carbonium ion. (author)

  16. On neutral plasma oscillations

    International Nuclear Information System (INIS)

    Shadwick, B.A.; Morrison, P.J.

    1993-06-01

    We examine the conditions for the existence of spectrally stable neutral modes in a Vlasov-Poisson plasma and show that for stable equilibria of systems that have unbounded spatial domain, the only possible neutral modes are those with phase velocities that correspond to stationary inflection points of the equilibrium distribution function. It is seen that these neutral modes can possess positive or negative free energy

  17. Neutral beam monitoring

    International Nuclear Information System (INIS)

    Fink, J.H.

    1979-01-01

    A neutral beam generated by passing accelerated ions through a walled cell containing a low energy neutral gas, such that charge exchange partially neutralizes the high energy beam, is monitored by detecting the current flowing through the cell wall produced by low energy ions which drift to the wall after the charge exchange. By segmenting the wall into radial and longitudinal segments various beam conditions are identified. (U.K.)

  18. On neutral plasma oscillations

    International Nuclear Information System (INIS)

    Shadwick, B.A.; Texas Univ., Austin; Morrison, P.J.; Texas Univ., Austin

    1994-01-01

    We examine the conditions for the existence of spectrally stable neutral modes in a Vlasov-Poisson plasma and show that for stable equilibria of systems that have unbounded spatial domain, the only possible neutral modes are those with phase velocities that correspond to stationary inflection points of the equilibrium distribution function. It is seen that these neutral modes can posses positive or negative free energy. (orig.)

  19. Search for neutral leptons

    International Nuclear Information System (INIS)

    Perl, M.L.

    1984-12-01

    At present we know of three kinds of neutral leptons: the electron neutrino, the muon neutrino, and the tau neutrino. This paper reviews the search for additional neutral leptons. The method and significance of a search depends upon the model used for the neutral lepton being sought. Some models for the properties and decay modes of proposed neutral leptons are described. Past and present searches are reviewed. The limits obtained by some completed searches are given, and the methods of searches in progress are described. Future searches are discussed. 41 references

  20. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu

    2017-04-27

    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  1. Cationic polymers and porous materials

    KAUST Repository

    Han, Yu; Tian, Qiwei; Dong, Xinglong; Liu, Zhaohui; Basset, Jean-Marie; Saih, Youssef; Sun, Miao; Xu, Wei; Shaikh, Sohel

    2017-01-01

    According to one or more embodiments, cationic polymers may be produced which include one or more monomers containing cations. Such cationic polymers may be utilized as structure directing agents to form mesoporous zeolites. The mesoporous zeolites may include micropores as well as mesopores, and may have a surface area of greater than 350 m2/g and a pore volume of greater than 0.3 cm3/g. Also described are core/shell zeolites, where at least the shell portion includes a mesoporous zeolite material.

  2. The cation-π interaction.

    Science.gov (United States)

    Dougherty, Dennis A

    2013-04-16

    The chemistry community now recognizes the cation-π interaction as a major force for molecular recognition, joining the hydrophobic effect, the hydrogen bond, and the ion pair in determining macromolecular structure and drug-receptor interactions. This Account provides the author's perspective on the intellectual origins and fundamental nature of the cation-π interaction. Early studies on cyclophanes established that water-soluble, cationic molecules would forego aqueous solvation to enter a hydrophobic cavity if that cavity was lined with π systems. Important gas phase studies established the fundamental nature of the cation-π interaction. The strength of the cation-π interaction (Li(+) binds to benzene with 38 kcal/mol of binding energy; NH4(+) with 19 kcal/mol) distinguishes it from the weaker polar-π interactions observed in the benzene dimer or water-benzene complexes. In addition to the substantial intrinsic strength of the cation-π interaction in gas phase studies, the cation-π interaction remains energetically significant in aqueous media and under biological conditions. Many studies have shown that cation-π interactions can enhance binding energies by 2-5 kcal/mol, making them competitive with hydrogen bonds and ion pairs in drug-receptor and protein-protein interactions. As with other noncovalent interactions involving aromatic systems, the cation-π interaction includes a substantial electrostatic component. The six (four) C(δ-)-H(δ+) bond dipoles of a molecule like benzene (ethylene) combine to produce a region of negative electrostatic potential on the face of the π system. Simple electrostatics facilitate a natural attraction of cations to the surface. The trend for (gas phase) binding energies is Li(+) > Na(+) > K(+) > Rb(+): as the ion gets larger the charge is dispersed over a larger sphere and binding interactions weaken, a classical electrostatic effect. On other hand, polarizability does not define these interactions. Cyclohexane is

  3. Synthetic cation-selective nanotube: permeant cations chaperoned by anions.

    Science.gov (United States)

    Hilder, Tamsyn A; Gordon, Dan; Chung, Shin-Ho

    2011-01-28

    The ability to design ion-selective, synthetic nanotubes which mimic biological ion channels may have significant implications for the future treatment of bacteria, diseases, and as ultrasensitive biosensors. We present the design of a synthetic nanotube made from carbon atoms that selectively allows monovalent cations to move across and rejects all anions. The cation-selective nanotube mimics some of the salient properties of biological ion channels. Before practical nanodevices are successfully fabricated it is vital that proof-of-concept computational studies are performed. With this in mind we use molecular and stochastic dynamics simulations to characterize the dynamics of ion permeation across a single-walled (10, 10), 36 Å long, carbon nanotube terminated with carboxylic acid with an effective radius of 5.08 Å. Although cations encounter a high energy barrier of 7 kT, its height is drastically reduced by a chloride ion in the nanotube. The presence of a chloride ion near the pore entrance thus enables a cation to enter the pore and, once in the pore, it is chaperoned by the resident counterion across the narrow pore. The moment the chaperoned cation transits the pore, the counterion moves back to the entrance to ferry another ion. The synthetic nanotube has a high sodium conductance of 124 pS and shows linear current-voltage and current-concentration profiles. The cation-anion selectivity ratio ranges from 8 to 25, depending on the ionic concentrations in the reservoirs.

  4. Simultaneous anionic and cationic redox

    Science.gov (United States)

    Jung, Sung-Kyun; Kang, Kisuk

    2017-12-01

    It is challenging to unlock anionic redox activity, accompanied by full utilization of available cationic redox process, to boost capacity of battery cathodes. Now, material design by tuning the metal-oxygen interaction is shown to be a promising solution.

  5. Cation disorder in Ga1212.

    Science.gov (United States)

    Greenwood, K B; Ko, D; Vander Griend, D A; Sarjeant, G M; Milgram, J W; Garrity, E S; DeLoach, D I; Poeppelmeier, K R; Salvador, P A; Mason, T O

    2000-07-24

    Substitution of calcium for strontium in LnSr2-xCaxCu2GaO7 (Ln = La, Pr, Nd, Gd, Ho, Er, Tm, and Yb) materials at ambient pressure and 975 degrees C results in complete substitution of calcium for strontium in the lanthanum and praseodymium systems and partial substitution in the other lanthanide systems. The calcium saturation level depends on the size of the Ln cation, and in all cases, a decrease in the lattice parameters with calcium concentration was observed until a common, lower bound, average A-cation size is reached. Site occupancies from X-ray and neutron diffraction experiments for LnSr2-xCaxCu2GaO7 (x = 0 and x = 2) confirm that the A-cations distribute between the two blocking-layer sites and the active-layer site based on size. A quantitative link between cation distribution and relative site-specific cation enthalpy for calcium, strontium, and lanthanum within the gallate structure is derived. The cation distribution in other similar materials can potentially be modeled.

  6. Process for production of electrical energy from the neutralization of acid and base in a bipolar membrane cell

    International Nuclear Information System (INIS)

    Walther, J.F.

    1982-01-01

    Electrical energy is generated from acid-base neutralization reactions in electrodialytic cells. Permselective bipolar membranes in these cells are contacted on their cation selective faces by aqueous acid streams and on their anion-selective faces by aqueous base streams. Spontaneous neutralization reactions between the basic anions and acidic cations through the bipolar membranes produce electrical potential differences between the acid and base streams. These potential differences are transmitted to electrodes to produce electrical energy which is withdrawn from the cell

  7. Liquid-solid extraction of cationic metals by cationic amphiphiles

    International Nuclear Information System (INIS)

    Muller, W.

    2010-01-01

    In the field of selective separation for recycling of spent nuclear fuel, liquid-liquid extraction processes are widely used (PUREX, DIAMEX..) in industrial scale. In order to guarantee a sustainable nuclear energy for the forthcoming generations, alternative reprocessing techniques are under development. One of them bases on the studies from Heckmann et al in the 80's and consists in selectively precipitating actinides from aqueous waste solutions by cationic surfactants (liquid-solid extraction). This technique has some interesting advantages over liquid-liquid extraction techniques, because several steps are omitted like stripping or solvent washing. Moreover, the amount of waste is decreased considerably, since no contaminated organic solvent is produced. In this thesis, we have carried out a physico-chemical study to understand the specific interactions between the metallic cations with the cationic surfactant. First, we have analysed the specific effect of the different counter-ions (Cl - , NO 3 - , C 2 O 4 2- ) and then the effect of alkaline cations on the structural properties of the surfactant aggregation in varying thermodynamical conditions. Finally, different multivalent cations (Cu 2+ , Zn 2+ , UO 2 2+ , Fe 3+ , Nd 3+ , Eu 3+ , Th 4+ ) were considered; we have concluded that depending on the anionic complex of these metals formed in acidic media, we can observe either an adsorption at the micellar interface or not. This adsorption has a large influence of the surfactant aggregation properties and determines the limits of the application in term of ionic strength, temperature and surfactant concentration. (author) [fr

  8. Neutralized transport experiment

    International Nuclear Information System (INIS)

    Roy, P.K.; Yu, S.S.; Eylon, S.; Henestroza, E.; Anders, A.; Gilson, E.P.; Bieniosek, F.M.; Greenway, W.G.; Logan, B.G.; Waldron, W.L.; Shuman, D.B.; Vanecek, D.L.; Welch, D.R.; Rose, D.V.; Thoma, C.; Davidson, R.C.; Efthimion, P.C.; Kaganovich, I.; Sefkow, A.B.; Sharp, W.M.

    2005-01-01

    Experimental details on providing active neutralization of high brightness ion beam have been demonstrated for Heavy Ion Fusion program. A K + beam was extracted from a variable-perveance injector and transported through 2.4 m long quadrupole lattice for final focusing. Neutralization was provided by a localized cathode arc plasma plug and a RF volume plasma system. Effects of beam perveance, emittance, convergence focusing angle, and axial focusing position on neutralization have been investigated. Good agreement has been observed with theory and experiment throughout the study

  9. Cation exchange interaction between antibiotic ciprofloxacin and montmorillonite

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Chih-Jen [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Department of Geosciences, National Taiwan University, Taipei 10617, Taiwan (China); Li, Zhaohui, E-mail: li@uwp.edu [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Department of Geosciences, University of Wisconsin - Parkside, Kenosha, WI 53144 (United States); Jiang, Wei-Teh, E-mail: atwtj@mail.ncku.edu.tw [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China); Jean, Jiin-Shuh; Liu, Chia-Chuan [Department of Earth Sciences, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan (China)

    2010-11-15

    Exploring the interactions between antibiotics and soils/minerals is of great importance in resolving their fate, transport, and elimination in the environment due to their frequent detection in wastewater, river water, sewage sludge and soils. This study focused on determining the adsorption properties and mechanisms of interaction between antibiotic ciprofloxacin and montmorillonite (SAz-1), a swelling dioctahedral mineral with Ca{sup 2+} as the main interlayer cation. In acidic and neutral aqueous solutions, a stoichiometric exchange between ciprofloxacin and interlayer cations yielded an adsorption capacity as high as 330 mg/g, corresponding to 1.0 mmol/g. When solution pH was above its pK{sub a2} (8.7), adsorption of ciprofloxacin was greatly reduced due to the net repulsion between the negatively charged clay surfaces and the ciprofloxacin anion. The uptake of ciprofloxacin expanded the basal spacing (d{sub 001}) of montmorillonite from 15.04 to 17.23 A near its adsorption capacity, confirming cation exchange within the interlayers in addition to surface adsorption. Fourier transform infrared results further suggested that the protonated amine group of ciprofloxacin in its cationic form was electrostatically attracted to negatively charged sites of clay surfaces, and that the carboxylic acid group was hydrogen bonded to the basal oxygen atoms of the silicate layers. The results indicate that montmorillonite is an effective sorbent to remove ciprofloxacin from water.

  10. Cation exchange interaction between antibiotic ciprofloxacin and montmorillonite

    International Nuclear Information System (INIS)

    Wang, Chih-Jen; Li, Zhaohui; Jiang, Wei-Teh; Jean, Jiin-Shuh; Liu, Chia-Chuan

    2010-01-01

    Exploring the interactions between antibiotics and soils/minerals is of great importance in resolving their fate, transport, and elimination in the environment due to their frequent detection in wastewater, river water, sewage sludge and soils. This study focused on determining the adsorption properties and mechanisms of interaction between antibiotic ciprofloxacin and montmorillonite (SAz-1), a swelling dioctahedral mineral with Ca 2+ as the main interlayer cation. In acidic and neutral aqueous solutions, a stoichiometric exchange between ciprofloxacin and interlayer cations yielded an adsorption capacity as high as 330 mg/g, corresponding to 1.0 mmol/g. When solution pH was above its pK a2 (8.7), adsorption of ciprofloxacin was greatly reduced due to the net repulsion between the negatively charged clay surfaces and the ciprofloxacin anion. The uptake of ciprofloxacin expanded the basal spacing (d 001 ) of montmorillonite from 15.04 to 17.23 A near its adsorption capacity, confirming cation exchange within the interlayers in addition to surface adsorption. Fourier transform infrared results further suggested that the protonated amine group of ciprofloxacin in its cationic form was electrostatically attracted to negatively charged sites of clay surfaces, and that the carboxylic acid group was hydrogen bonded to the basal oxygen atoms of the silicate layers. The results indicate that montmorillonite is an effective sorbent to remove ciprofloxacin from water.

  11. Are "Market Neutral" Hedge Funds Really Market Neutral?

    OpenAIRE

    Andrew J. Patton

    2009-01-01

    Using a variety of different definitions of "neutrality," this study presents significant evidence against the neutrality to market risk of hedge funds in a range of style categories. I generalize standard definitions of "market neutrality," and propose five different neutrality concepts. I suggest statistical tests for each neutrality concept, and apply these tests to a database of monthly returns on 1423 hedge funds from five style categories. For the "market neutral" style, approximately o...

  12. Bunched beam neutralization

    International Nuclear Information System (INIS)

    Gammel, G.M.; Maschke, A.W.; Mobley, R.M.

    1979-01-01

    One of the steps involved in producing an intense ion beam from conventional accelerators for Heavy Ion Fusion (HIF) is beam bunching. To maintain space charge neutralized transport, neutralization must occur more quickly as the beam bunches. It has been demonstrated at BNL that a 60 mA proton beam from a 750 kV Cockcroft--Walton can be neutralized within a microsecond. The special problem in HIF is that the neutralization must occur in a time scale of nanoseconds. To study neutralization on a faster time scale, a 40 mA, 450 kV proton beam was bunched at 16 MHz. A biased Faraday cup sampled the bunched beam at the position where maximum bunching was nominally expected, about 2.5 meters from the buncher. Part of the drift region, about 1.8 meters, was occupied by a series of Gabor lenses. In addition to enhancing beam transport by transverse focussing, the background cloud of electrons in the lenses provided an extra degree of neutralization. With no lens, the best bunch factor was at least 20. Bunch factor is defined here as the ratio of the distance between bunches to the FWHM bunch length. With the lens, it was hoped that the increased plasma frequency would decrease the neutralization time and cause an increase in the bunch factor. In fact, with the lens, the instantaneous current increased about three times, but the bunch factor dropped to about 10. Even with the lens, the FWHM of the bunches at the position of maximum bunching was still comparable to or less than the oscillation period of the surrounding electron plasma. Thus, the electron density in the lens must increase before neutralization could be effective in this case, or bunching should be done at a lower frequency

  13. Protic Cationic Oligomeric Ionic Liquids of the Urethane Type

    DEFF Research Database (Denmark)

    Shevchenko, V. V.; Stryutsky, A. V.; Klymenko, N. S.

    2014-01-01

    Protic oligomeric cationic ionic liquids of the oligo(ether urethane) type are synthesized via the reaction of an isocyanate prepolymer based on oligo(oxy ethylene)glycol with M = 1000 with hexamethylene-diisocyanate followed by blocking of the terminal isocyanate groups with the use of amine...... derivatives of imidazole, pyridine, and 3-methylpyridine and neutralization of heterocycles with ethanesulfonic acid and p-toluenesulfonic acid. The structures and properties of the synthesized oligomeric ionic liquids substantially depend on the structures of the ionic groups. They are amorphous at room...... temperature, but ethanesulfonate imidazolium and pyridinium oligomeric ionic liquids form a low melting crystalline phase. The proton conductivities of the oligomeric ionic liquids are determined by the type of cation in the temperature range 80-120 degrees C under anhydrous conditions and vary within five...

  14. Elementary steps of the catalytic oxidation of CO in a gas phase in the presence of rhenium cations with carbonyl and oxygen ligands: a comparison with heterogeneous catalysis

    International Nuclear Information System (INIS)

    Goncharov, V.B.; Fialko, E.F.; Shejnin, D.Eh.; Kikhtenko, A.V.

    1997-01-01

    Reactivity in a gaseous phase o rhenium (Re + ) and rhenium monocarbonyl (ReCO + ) in the reaction of CO oxidation in oxygen-containing reagents (NO, O 2 , H 2 O) is studied through the method of the ionic cyclotron resonance. It is shown that presence of carbonyl ligand essentially influences the ion reactivity. The effective channel of the metal monocarbonyl ions oxidation through molecular oxygen is found. Accounting for this stage makes of possible to explain the low-temperature activity of a number of oxide catalyzer Mo, W in the reaction of CO oxidation by molecular oxygen

  15. Extraction chemistry of actinide cations by N,N-dialkylamides

    International Nuclear Information System (INIS)

    Condamines, N.; Musikas, C.

    1990-01-01

    N,N-dialkylamides are alternate extractants to tributylphosphate, TBP, for the actinides separation in nuclear fuel reprocessing. Extraction mechanisms of UO 2 2+ and Pu 4+ from nitric acid media are investigated for the amides DOBA and DOiBA. For low acidities, amides are neutral extractants. The stoechiometries of UO 2 (NO 3 ) 2 (Amide) 2 (Amide = DOBA or DOiBA), Pu(NO 3 ) 4 (DOBA) 2 are established. A bond between the oxygen of the carbonyl group and the metallic cation is the driving force of the transfer

  16. New double-cation borohydrides

    Energy Technology Data Exchange (ETDEWEB)

    Lindemann, Inge; Domenech Ferrer, Roger; Schultz, Ludwig; Gutfleisch, Oliver [IFW Dresden, Institute for Metallic Materials, P.O. Box 270016, 01171 Dresden (Germany); Filinchuk, Yaroslav [Swiss-Norwegian Beam Lines at ESRF, BP-220, 38043 Grenoble (France); Hagemann, Hans; Cerny, Radovan [Department of Physical Chemistry and Crystallography, University of Geneva, 1211 Geneva (Switzerland)

    2011-07-01

    Complex hydrides are under consideration for on-board hydrogen storage due to their high hydrogen density. However, up to now conventional borohydrides are either too stable or unstable for applications as in PEM fuel cells (60-120 C). Recently, double-cation borohydride systems have attracted great interest. The desorption temperature of the borohydrides decreases with increasing electronegativity of the cation. Consequently, it is possible to tailor a feasible on-board hydrogen storage material by the combination of appropriate cations. The stability was found to be intermediate between the single-cation borohydride systems. Two combinations were sucessfully synthesised by metathesis reaction via high energy ball milling. Al-Li-borohydride shows desorption at about 70 C combined with a very high hydrogen density (17.2 wt.%) and the Na-Al-borohydride (14.2 wt.%) decomposes around 90 C. Both desorption temperatures are in the target range for applications. The decomposition pathways were observed by in-situ-Raman spectroscopy, DSC (Differential Scanning Calorimetry), TG (Thermogravimetry) and thermal desorption measurements.

  17. Synthesis and characterization of a homogeneous and silica supported homoleptic cationic tungsten(vi) methyl complex: application in olefin metathesis

    KAUST Repository

    Dey, Raju

    2016-08-19

    A method for the synthesis of a homogeneous cationic tungsten(VI)penta-methyl complex [(WMe5)(+)(C6F5)(3)BMe-] from neutral tungstenhexamethyl (WMe6) and a silica supported cationic tungstentetramethyl complex [( Si-O-)WMe4+ (C6F5)(3)BMe-] from a neutral silica supported tungstenpentamethyl complex [( Si-O-)WMe5] is described. In both cases a direct demethylation using the B(C6F5)(3) reagent was used. The aforesaid complexes were characterized by liquid or solid state NMR spectroscopy. Interestingly, the homogeneous cationic complex [(WMe5)(+)(C6F5)(3)BMe-] shows moderate activity whereas the supported cationic complex [( Si-O-)WMe4+(C6F5)(3)BMe-] exhibits good activity in olefin metathesis reactions.

  18. Synthesis and characterization of a homogeneous and silica supported homoleptic cationic tungsten(vi) methyl complex: application in olefin metathesis

    KAUST Repository

    Dey, Raju; Samantaray, Manoja; Poater, Albert; Hamieh, Ali Imad Ali; Kavitake, Santosh Giridhar; Abou-Hamad, Edy; Callens, Emmanuel; Emwas, Abdul-Hamid M.; Cavallo, Luigi; Basset, Jean-Marie

    2016-01-01

    A method for the synthesis of a homogeneous cationic tungsten(VI)penta-methyl complex [(WMe5)(+)(C6F5)(3)BMe-] from neutral tungstenhexamethyl (WMe6) and a silica supported cationic tungstentetramethyl complex [( Si-O-)WMe4+ (C6F5)(3)BMe-] from a neutral silica supported tungstenpentamethyl complex [( Si-O-)WMe5] is described. In both cases a direct demethylation using the B(C6F5)(3) reagent was used. The aforesaid complexes were characterized by liquid or solid state NMR spectroscopy. Interestingly, the homogeneous cationic complex [(WMe5)(+)(C6F5)(3)BMe-] shows moderate activity whereas the supported cationic complex [( Si-O-)WMe4+(C6F5)(3)BMe-] exhibits good activity in olefin metathesis reactions.

  19. Liquid-solid extraction of metallic cations by cationic amphiphiles

    International Nuclear Information System (INIS)

    Mueller, Wolfram; Sievers, Torsten K.; Zemb, Thomas; Diat, Olivier; Sievers, Torsten K.; Dejugnat, Christophe

    2012-01-01

    In the field of selective metal ion separation, liquid-liquid extraction is usually conducted through an emulsion mixing of hydrophobic complexants dispersed in an organic phase and acidic water containing the ionic species. Recently, it has been shown that amphiphilic complexants could influence strongly extraction efficiency by enhancing the interfacial interaction between the metal ion in the aqueous and the complexant in the organic phase. Moreover, these amphiphiles can also substitute the organic phase if an appropriate aliphatic chain is chosen. The dispersion of such amphiphilic complexants in an aqueous solution of salt mixtures is not only attractive for studying specific interactions but also to better the understanding of complex formation in aqueous solution of multivalent metal ions, such as lanthanides and actinides. This understanding is of potential interest for a broad range of industries including purification of rare earth metals and pollute treatment e.g. of fission byproducts. This principle can also be applied to liquid-solid extraction, where the final state of the separation is a solid phase containing the selectively extracted ions. Indeed, a novel solid-liquid extraction method exploits the selective precipitation of metal ions from an aqueous salt mixture using a cationic surfactant, below its Krafft point (temperature below which the long aliphatic chains of surfactant crystallize). This technique has been proven to be highly efficient for the separation of actinides and heavy metal using long chain ammonium or pyridinium amphiphiles. The most important point in this process is the recognition of cationic metal ions by cationic surfactants. By computing the free energy of the polar head group per micelle as a function of the different counter-anions, we have demonstrated for the first time that different interactions exist between the micellar surface and the ions. These interactions depend on the nature of the cation but also on

  20. Cyanide ion complexation by a cationic borane.

    Science.gov (United States)

    Chiu, Ching-Wen; Gabbaï, François P

    2008-02-14

    While we have previously reported that [1-(Mes2B)-8-(Me3NCH2)-C10H6]+ ([2]+) complexes fluoride ions to form [1-(Mes2FB)-8-(Me3NCH2)-C10H6] (2-F), we now show that this cationic borane also complexes cyanide to form [1-(Mes2(NC)B)-8-(Me3NCH2)-C10H6] (2-CN). This reaction also occurs under biphasic conditions (H2O-CHCl3) and may serve to transport cyanide in organic phases. The zwitterionic cyanoborate 2-CN has been fully characterized and its crystal structure determined. UV-vis titration experiments carried out in THF indicate that [2]+ has a higher affinity for fluoride (K > 10(8) M(-1)) than cyanide (K = 8.0 (+/-0.5) x 10(5) M(-1)). Steric effects which impede cyanide binding to the sterically congested boron center of [2]+ are most likely at the origin of this selectivity. Finally, electrochemical studies indicate that [2]+ is significantly more electrophilic than its neutral precursor 1-(Mes2B)-8-(Me2NCH2)-(C10H6) (1). These studies also show that reduction of [2]+ is irreversible, possibly because of elimination of the NMe3 moiety under reductive conditions. In fact, [2]OTf reacts with NaBH4 to afford 1-(Mes2B)-8-(CH3)-(C10H6) (4) which has also been fully characterized.

  1. Neutral beam development plan

    International Nuclear Information System (INIS)

    Staten, H.S.

    1980-08-01

    The national plan is presented for developing advanced injection systems for use on upgrades of existing experiments, and use on future facilities such as ETF, to be built in the late 1980's or early 90's where power production from magnetic fusion will move closer to a reality. Not only must higher power and longer pulse length systems be developed , but they must operate reliably; they must be a tool for the experimenter, not the experiment itself. Neutral beam systems handle large amounts of energy and as such, they often are as complicated as the plasma physics experiment itself. This presents a significant challenge to the neutral beam developer

  2. Neutral beam program

    International Nuclear Information System (INIS)

    Anon.

    1979-01-01

    The structure of the beam injection program for the Doublet-3 device is discussed. The design considerations for the beam line and design parameters for the Doublet-3 ion souce are given. Major components of the neutral beam injector system are discussed in detail. These include the neutralizer, magnetic shielding, reflecting magnets, vacuum system, calorimeter and beam dumps, and drift duct. The planned location of the two-injector system for Doublet-3 is illustrated and site preparation is considered. The status of beamline units 1 and 2 and the future program schedule are discussed

  3. Tripodal receptors for cation and anion sensors

    NARCIS (Netherlands)

    Kuswandi, Bambang; Nuriman, [Unknown; Verboom, Willem; Reinhoudt, David

    2006-01-01

    This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing

  4. Heavy metal cations permeate the TRPV6 epithelial cation channel.

    Science.gov (United States)

    Kovacs, Gergely; Danko, Tamas; Bergeron, Marc J; Balazs, Bernadett; Suzuki, Yoshiro; Zsembery, Akos; Hediger, Matthias A

    2011-01-01

    TRPV6 belongs to the vanilloid family of the transient receptor potential channel (TRP) superfamily. This calcium-selective channel is highly expressed in the duodenum and the placenta, being responsible for calcium absorption in the body and fetus. Previous observations have suggested that TRPV6 is not only permeable to calcium but also to other divalent cations in epithelial tissues. In this study, we tested whether TRPV6 is indeed also permeable to cations such as zinc and cadmium. We found that the basal intracellular calcium concentration was higher in HEK293 cells transfected with hTRPV6 than in non-transfected cells, and that this difference almost disappeared in nominally calcium-free solution. Live cell imaging experiments with Fura-2 and NewPort Green DCF showed that overexpression of human TRPV6 increased the permeability for Ca(2+), Ba(2+), Sr(2+), Mn(2+), Zn(2+), Cd(2+), and interestingly also for La(3+) and Gd(3+). These results were confirmed using the patch clamp technique. (45)Ca uptake experiments showed that cadmium, lanthanum and gadolinium were also highly efficient inhibitors of TRPV6-mediated calcium influx at higher micromolar concentrations. Our results suggest that TRPV6 is not only involved in calcium transport but also in the transport of other divalent cations, including heavy metal ions, which may have toxicological implications. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Mod en neutral seksualitet!

    DEFF Research Database (Denmark)

    Leer, Jonatan

    2013-01-01

    Towards a Neutral Sexuality! or Roland Barthes as a Queer Thinker? This article argues that the work of Roland Barthes has interesting perspectives in common with the queer theory. This argument will be put forward by using his concept of ‘the neutral’ that Barthes defines as “that which outplays...

  6. Issues in neutral currents

    International Nuclear Information System (INIS)

    Sehgal, L.M.

    1980-01-01

    The experimental results on low energy confirming the structure of the effective Lagrangian of the weak neutral current processes as predicted by the Salam-Weinberg model are reviewed. Some possible modifications of the effective Lagrangian and the feasibility of their experimental verification are also considered. (P.L.)

  7. ITER neutral beam system

    International Nuclear Information System (INIS)

    Mondino, P.L.; Di Pietro, E.; Bayetti, P.

    1999-01-01

    The Neutral Beam (NB) system for the International Thermonuclear Experimental Reactor (ITER) has reached a high degree of integration with the tokamak and with the rest of the plant. Operational requirements and maintainability have been considered in the design. The paper considers the integration with the tokamak, discusses design improvements which appear necessary and finally notes R and D progress in key areas. (author)

  8. Cationic electrodepositable coating composition comprising lignin

    Science.gov (United States)

    Fenn, David; Bowman, Mark P; Zawacky, Steven R; Van Buskirk, Ellor J; Kamarchik, Peter

    2013-07-30

    A cationic electrodepositable coating composition is disclosed. The present invention in directed to a cationic electrodepositable coating composition comprising a lignin-containing cationic salt resin, that comprises (A) the reaction product of: lignin, an amine, and a carbonyl compound; (B) the reaction product of lignin, epichlorohydrin, and an amine; or (C) combinations thereof.

  9. Asymmetric cation-binding catalysis

    DEFF Research Database (Denmark)

    Oliveira, Maria Teresa; Lee, Jiwoong

    2017-01-01

    The employment of metal salts is quite limited in asymmetric catalysis, although it would provide an additional arsenal of safe and inexpensive reagents to create molecular functions with high optical purity. Cation chelation by polyethers increases the salts' solubility in conventional organic...... solvents, thus increasing their applicability in synthesis. The expansion of this concept to chiral polyethers led to the emergence of asymmetric cation-binding catalysis, where chiral counter anions are generated from metal salts, particularly using BINOL-based polyethers. Alkali metal salts, namely KF...... highly enantioselective silylation reactions in polyether-generated chiral environments, and leading to a record-high turnover in asymmetric organocatalysis. This can lead to further applications by the asymmetric use of other inorganic salts in various organic transformations....

  10. Inhibition of Neutral Red Photolysis with Different Antioxidants

    Directory of Open Access Journals (Sweden)

    Zlatan Rimpapa

    2007-02-01

    Full Text Available Neutral red is a dye the azine structure which has been used as an acido-base indicator and a dye in histochemistry. In 1960 Goldhaber introduced Neutral red into the medium of resorbing bone cultures to localize the osteoclast in the living cultures. Using time-lapse microcinematography in order to follow the osteoclasts, he reported excellent contrast could be obtained with Neutral red due to the avidity of osteoclasts for this dye. Unfortunately, however, the photodynamic effect resulting from subsequent exposure of these cultures to light precluded this approach, and again in 1963. it was observed that the death of the osteoclasts was probably due to a photodynamic effect related to the dye in the cell, the presence of oxygen and the frequent exposure of light by our time-lapse photography. VIS and UV irradiation induced photolysis of Neutral red, and from Neutral red cation produced with photons a Neutral red radical. This Neutral red radical can be inhibited with action of an antioxidant, such as melatonin, glutathione, ascorbic acid, E vitamin, etc. We developed an assay with Neutral redphotolysis which utilizes a VIS and UV irradiation technique for quantification the inhibition of photolysis with action of an antioxidant. In this method Neutral red acts double, as a free radical generator and as a photosensitizer.

  11. Liposomes containing cationic dimethyl dioctadecyl ammonium bromide: formulation, quality control, and lipofection efficiency.

    Science.gov (United States)

    Dass, Crispin R; Walker, Todd L; Burton, Mark A

    2002-01-01

    This article describes a novel, simple, and relatively inexpensive method to prepare cationic liposomes using an ethanol injection/pressure extrusion method. The study also demonstrated that binding erythrosine dye to cationic liposomes results in a shift of the absorption maximum of the dye from 528 nm to 549 nm at pH 4.25, allowing quantification and visualization of these vesicles. In addition, a relatively simple Ficoll-based gradient centrifugation method for separation of lipoplexes from unbound molecules is presented. Laboratory-formulated dimethyl dioctadecyl ammonium bromide (DDAB) containing liposomes were just as efficient in complexing nucleic acids as commercially available types, and binding increased as the positive to neutral lipid ratio was increased. Transfection efficiency of the DDAB-containing liposomes increased as the ratio of cationic to neutral lipid was increased from 1:1 to 4:1 with either PtdChol or DOPE as the neutral lipid. A concomitant increase in cytotoxicity of CSU-SA1 cancer cells was noted as the ratio of positive to neutral lipid of the liposomes was increased. Nevertheless, our present study showed that the 2:1 liposome is a good choice since it delivers functional plasmids at a comparable rate to commercial liposome formulations, has similar toxicities to the less harmful commercial liposomes, and is at least 1000-fold more economical to prepare inhouse, a major factor to be considered in preclinical and clinical studies with these carriers.

  12. Non-immunogenic, hydrophilic/cationic block copolymers and uses thereof

    Science.gov (United States)

    Scales, Charles W.; Huang, Faqing; McCormick, Charles L.

    2010-05-18

    The present invention provides novel non-immunogenic, hydrophilic/cationic block copolymers comprising a neutral-hydrophilic polymer and a cationic polymer, wherein both polymers have well-defined chain-end functionality. A representative example of such a block copolymer comprises poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA) and poly(N-[3-(dimethylamino)propyl]methacrylamide) (PDMAPMA). Also provided is a synthesis method thereof in aqueous media via reversible addition fragmentation chain transfer (RAFT) polymerization. Further provided are uses of these block copolymers as drug delivery vehicles and protection agents.

  13. Investigation of electrochemical intrusion of cations by the method of contact electric resistance

    International Nuclear Information System (INIS)

    Marichev, V.A.

    1997-01-01

    Paper shows the possibility and prospects of application of contact electric resistance technique (CER) to study in-situ the initial stages of electrochemical admission of cations (ECA). ECA is shown to increase CER of metals. It enables to determine ECA potential and to investigate kinetics of this process. Using ECA in copper, silver and zinc from alkali solutions as an example one has shown that CER technique enables to obtain results that do not contradict well-known published data. Potentials of ECA cations from acid and neutral solutions in copper, platinum, iron, titanium and tungsten are determined

  14. Antihypertensive neutral lipid

    Science.gov (United States)

    Snyder, F.L.; Blank, M.L.

    1984-10-26

    The invention relates to the discovery of a class of neutral acetylated either-linked glycerolipids having the capacity to lower blood presure in warm-blooded animals. This physiological effect is structure sensitive requiring a long chain alkyl group at the sn-1 position and a short carbon chain acyl group (acetyl or propionyl) at the sn-2 position, and a hydroxyl group at the sn-3 position.

  15. Exercise Equipment: Neutral Buoyancy

    Science.gov (United States)

    Shackelford, Linda; Valle, Paul

    2016-01-01

    Load Bearing Equipment for Neutral Buoyancy (LBE-NB) is an exercise frame that holds two exercising subjects in position as they apply counter forces to each other for lower extremity and spine loading resistance exercises. Resistance exercise prevents bone loss on ISS, but the ISS equipment is too massive for use in exploration craft. Integrating the human into the load directing, load generating, and motion control functions of the exercise equipment generates safe exercise loads with less equipment mass and volume.

  16. Neutral beams for mirrors

    International Nuclear Information System (INIS)

    Fink, J.H.

    1983-01-01

    An important demonstration of negative ion technology is proposed for FY92 in the MFTF-α+T, an upgrade of the Mirror Fusion Test Facility at the Lawrence Livermore National Laboratory. This facility calls for 200-keV negative ions to form neutral beams that generate sloshing ions in the reactor end plugs. Three different beam lines are considered for this application. Their advantages and disadvantages are discussed

  17. Gargamelle: neutral current event

    CERN Multimedia

    1973-01-01

    This event shows real tracks of particles from the 1200 litre Gargamelle bubble chamber that ran on the PS from 1970 to 1976 and on the SPS from 1976 to 1979. In this image a neutrino passes close to a nucleon and reemerges as a neutrino. Such events are called neutral curent, as they are mediated by the Z0 boson which has no electric charge.

  18. Climate Neutral Campus Key Terms and Definitions | Climate Neutral Research

    Science.gov (United States)

    Campuses | NREL Neutral Campus Key Terms and Definitions Climate Neutral Campus Key Terms and Definitions The term climate neutral evolved along with net zero and a number of other "green" and accuracy in these areas lets research campuses know exactly how close they are to climate

  19. Comparison of cation adsorption by isostructural rutile and cassiterite.

    Science.gov (United States)

    Machesky, Michael; Wesolowski, David; Rosenqvist, Jörgen; Předota, Milan; Vlcek, Lukas; Ridley, Moira; Kohli, Vaibhav; Zhang, Zhan; Fenter, Paul; Cummings, Peter; Lvov, Serguei; Fedkin, Mark; Rodriguez-Santiago, Victor; Kubicki, James; Bandura, Andrei

    2011-04-19

    Macroscopic net proton charging curves for powdered rutile and cassiterite specimens with the (110) crystal face predominant, as a function of pH in RbCl and NaCl solutions, trace SrCl(2) in NaCl, and trace ZnCl(2) in NaCl and Na Triflate solutions, are compared to corresponding molecular-level information obtained from static DFT optimizations and classical MD simulations, as well as synchrotron X-ray methods. The similarities and differences in the macroscopic charging behavior of rutile and cassiterite largely reflect the cation binding modes observed at the molecular level. Cation adsorption is primarily inner-sphere on both isostructural (110) surfaces, despite predictions that outer-sphere binding should predominate on low bulk dielectric constant oxides such as cassiterite (ε(bulk) ≈ 11). Inner-sphere adsorption is also significant for Rb(+) and Na(+) on neutral surfaces, whereas Cl(-) binding is predominately outer-sphere. As negative surface charge increases, relatively more Rb(+), Na(+), and especially Sr(2+) are bound in highly desolvated tetradentate fashion on the rutile (110) surface, largely accounting for enhanced negative charge development relative to cassiterite. Charging curves in the presence of Zn(2+) are very steep but similar for both oxides, reflective of Zn(2+) hydrolysis (and accompanying proton release) during the adsorption process, and the similar binding modes for ZnOH(+) on both surfaces. These results suggest that differences in cation adsorption between high and low bulk dielectric constant oxides are more subtly related to the relative degree of cation desolvation accompanying inner-sphere binding (i.e., more tetradentate binding on rutile), rather than distinct inner- and outer-sphere adsorption modes. Cation desolvation may be favored at the rutile (110) surface in part because inner-sphere water molecules are bound further from and less tightly than on the cassiterite (110) surface. Hence, their removal upon inner

  20. Cation-Coupled Bicarbonate Transporters

    OpenAIRE

    Aalkjaer, Christian; Boedtkjer, Ebbe; Choi, Inyeong; Lee, Soojung

    2014-01-01

    Cation-coupled HCO3− transport was initially identified in the mid-1970s when pioneering studies showed that acid extrusion from cells is stimulated by CO2/HCO3− and associated with Na+ and Cl− movement. The first Na+-coupled bicarbonate transporter (NCBT) was expression-cloned in the late 1990s. There are currently five mammalian NCBTs in the SLC4-family: the electrogenic Na,HCO3-cotransporters NBCe1 and NBCe2 (SLC4A4 and SLC4A5 gene products); the electroneutral Na,HCO3-cotransporter NBCn1 ...

  1. Cation disorder in shocked orthopyroxene.

    Science.gov (United States)

    Dundon, R. W.; Hafner, S. S.

    1971-01-01

    The study of cation distributions over nonequivalent lattice sites in minerals may reveal information on the history of temperature and pressure in rocks. Chemically homogeneous orthopyroxene specimens were shocked under well-controlled conditions in the laboratory in order to provide a basis for the interpretation of more complex natural materials. As a result of the investigation it is concluded that the distribution of magnesium and iron over the M1 and M2 positions in Bamle enstatite shocked at 1 megabar is highly disordered. It corresponds to an equilibrium distribution of at least 1000 C.

  2. Cation coordination in oxychloride glasses

    Energy Technology Data Exchange (ETDEWEB)

    Johnson, J A [Energy Technology Division, Argonne National Laboratory, Argonne, IL (United States); Holland, D [Physics Department, Warwick University, Coventry (United Kingdom); Bland, J [Physics Department, University of Liverpool, PO Box 147, Liverpool (United Kingdom); Johnson, C E [Physics Department, Northern Illinois University, DeKalb, IL (United States); Thomas, M F [Physics Department, University of Liverpool, PO Box 147, Liverpool (United Kingdom)

    2003-02-19

    Glasses containing mixtures of cations and anions of nominal compositions [Sb{sub 2}O{sub 3}]{sub x} - [ZnCl{sub 2}]{sub 1-x} where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Moessbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb){sub 2}(OZn)] and [Zn(ClZn){sub 2}(OSb){sub 2}].

  3. Cation coordination in oxychloride glasses

    International Nuclear Information System (INIS)

    Johnson, J A; Holland, D; Bland, J; Johnson, C E; Thomas, M F

    2003-01-01

    Glasses containing mixtures of cations and anions of nominal compositions [Sb 2 O 3 ] x - [ZnCl 2 ] 1-x where x = 0.25, 0.50, 0.75, and 1.00, have been studied by means of neutron diffraction and Raman and Moessbauer spectroscopy. There is preferential bonding within the system with the absence of Sb-Cl bonds. Antimony is found to be threefold coordinated to oxygen, and zinc fourfold coordinated. The main contributing species are of the form [Sb(OSb) 2 (OZn)] and [Zn(ClZn) 2 (OSb) 2

  4. The Free Tricoordinated Silyl Cation Problem

    Directory of Open Access Journals (Sweden)

    Čičak, H.

    2010-03-01

    Full Text Available As the importance and abundance of silicon in our environment is large, it has been thought that silicon might take the place of carbon in forming a host of similar compounds and silicon-based life. However, until today there is no experimental evidence for such a hypothesis and carbon is still unique among the elements in the vast number and variety of compounds it can form. Also, the corresponding derivatives of the two elements show considerable differences in their chemical properties.The essential debate concerning organosilicon chemistry relates to the existence of the free planar tricoordinated silyl cations in condensed phase (R3Si+, in analogy to carbocations (R3C+ which have been known and characterized as free species. Although silyl cations are thermodynamically more stable than their carbon analogs, they are very reactive due to their high inherent electrophilicity and the ability of hypervalent coordination. On the other hand, stabilization by inductive and hyperconjugative effects and larger steric effects of carbocations make them less sensitive to solvation or other environmental effects than silyl cations. Hence, observation of free silyl cations in the condensed phase proved extremely difficult and the actual problem is the question of the degree of the (remaining silyl cation character.The first free silyl cation, trimesitylsilyl cation, and in analogy with it tridurylsilyl cation, were synthesized by Lambert et al. Free silyl cations based on analogy to aromatic ions (homocyclopropenylium and tropylium have also been prepared. However, in these silyl cations the cationic character is reduced by internal π -conjugation. Čičak et al. prepared some silyl-cationic intermediates (Me3Si--CH≡CR+in solid state. With the help of quantum-mechanical calculations it was concluded that these adducts have much more silyl cation than carbocation character.

  5. Bremsstrahlung and neutral currents

    International Nuclear Information System (INIS)

    Ellis, R.G.; McKellar, B.H.J.

    1979-01-01

    The utility of the bremsstrahlung process in detecting parity violations from V-A weak neutral current interference is analysed in two ways. Firstly, bremsstrahlung from polarized lepton-nucleus scattering has an asymmetry with respect to the polarization of the incident leptons, and secondly, bremsstrahlung from unpolarized lepton nucleus scattering has a small circular polarization. The magnitude of each effect is calculated. The ratio of the parity violating contribution and the parity conserving contribution to the cross section is shown to be a misleading measure of the utility of these experiments. A parameter, the figure of merit, is introduced and used to discuss the feasibility of possible experiments

  6. Plasma neutralizer for H- beams

    International Nuclear Information System (INIS)

    Grossman, M.W.

    1977-01-01

    Neutralization of H - beams by a hydrogen plasma is discussed. Optimum target thickness and maximum neutralization efficiency as a function of the fraction of the hydrogen target gas ionized is calculated for different H - beam energies. Also, the variation of neutralization efficiency with respect to target thickness for different H - beam energies is computed. The dispersion of the neutralized beam by a magnetic field for different energies and different values of B . z is found. Finally, a type of plasma jet is proposed, which may be suitable for a compact H - neutralizer

  7. Effect of cation size and charge on the interaction between silica surfaces in 1:1, 2:1, and 3:1 aqueous electrolytes.

    Science.gov (United States)

    Dishon, Matan; Zohar, Ohad; Sivan, Uri

    2011-11-01

    Application of two complementary AFM measurements, force vs separation and adhesion force, reveals the combined effects of cation size and charge (valency) on the interaction between silica surfaces in three 1:1, three 2:1, and three 3:1 metal chloride aqueous solutions of different concentrations. The interaction between the silica surfaces in 1:1 and 2:1 salt solutions is fully accounted for by ion-independent van der Waals (vdW) attraction and electric double-layer repulsion modified by cation specific adsorption to the silica surfaces. The deduced ranking of mono- and divalent cation adsorption capacity (adsorbability) to silica, Mg(2+) cation bare size as well as cation solvation energy but does not correlate with hydrated ionic radius or with volume or surface ionic charge density. In the presence of 3:1 salts, the coarse phenomenology of the force between the silica surfaces as a function of salt concentration resembles that in 1:1 and 2:1 electrolytes. Nevertheless, two fundamental differences should be noticed. First, the attraction between the silica surfaces is too large to be attributed solely to vdW force, hence implying an additional attraction mechanism or gross modification of the conventional vdW attraction. Second, neutralization of the silica surfaces occurs at trivalent cation concentrations that are 3 orders of magnitude smaller than those characterizing surface neutralization by mono- and divalent cations. Consequently, when trivalent cations are added to our cation adsorbability series the correlation with bare ion size breaks down abruptly. The strong adsorbability of trivalent cations to silica contrasts straightforward expectations based on ranking of the cationic solvation energies, thus suggesting a different adsorption mechanism which is inoperative or weak for mono- and divalent cations.

  8. ADSORPTION METHOD FOR SEPARATING METAL CATIONS

    Science.gov (United States)

    Khym, J.X.

    1959-03-10

    The chromatographic separation of fission product cations is discussed. By use of this method a mixture of metal cations containing Zr, Cb, Ce, Y, Ba, and Sr may be separated from one another. Mentioned as preferred exchange adsorbents are resins containing free sulfonic acid groups. Various eluants, such as tartaric acid, HCl, and citric acid, used at various acidities, are employed to effect the selective elution and separation of the various fission product cations.

  9. Electronic spectra of astrophysically interesting cations

    Energy Technology Data Exchange (ETDEWEB)

    Maier, John P., E-mail: j.p.maier@unibas.ch; Rice, Corey A., E-mail: j.p.maier@unibas.ch; Mazzotti, Fabio J., E-mail: j.p.maier@unibas.ch; Johnson, Anatoly, E-mail: j.p.maier@unibas.ch [Department of Chemistry, University of Basel, Klingelbergstr. 80, CH-4056 Basel (Switzerland)

    2015-01-22

    The electronic spectra of polyacetylene cations were recorded at 20K in the laboratory in an ion trap instrument. These can then be compared with diffuse interstellar band (DIB) absorptions. Examination of recently published data shows that the attribution of a weak DIB at ∼506.9 nm to diacetylene cation is not justified. Study of the higher excited electronic states of polyacetylene cations shows that their widths can still be sufficiently narrow for consideration as DIB carriers.

  10. UV/Vis/NIR spectral properties of triarylamines and their corresponding radical cations

    International Nuclear Information System (INIS)

    Amthor, Stephan; Noller, Bastian; Lambert, Christoph

    2005-01-01

    The one-electron oxidation potential of 10 triarylamines 1-10 with all permutations of chloro-, methoxy- and methyl-substituents in the three para-positions were determined by cyclic voltammetry. The half wave potential E 1/2 (I) of the first oxidation wave correlates linearly with the number of chloro- and methoxy-substituents. A high long-term stability of the first oxidation wave for all triarylamines was observed by multi-cycle thin-layer measurements. AM1-CISD derived values of the absorption energies are in good agreement with the experiments but differ strongly for the oscillator strengths as well as for neutral compounds 1-10 and their corresponding mono radical cations. The small solvent dependence of the experimental UV/Vis spectra in CH 2 Cl 2 and MeCN reflects a minor charge transfer (CT) character of the electronic transitions of neutral and cationic compounds

  11. Neutral helium beam probe

    Science.gov (United States)

    Karim, Rezwanul

    1999-10-01

    This article discusses the development of a code where diagnostic neutral helium beam can be used as a probe. The code solves numerically the evolution of the population densities of helium atoms at their several different energy levels as the beam propagates through the plasma. The collisional radiative model has been utilized in this numerical calculation. The spatial dependence of the metastable states of neutral helium atom, as obtained in this numerical analysis, offers a possible diagnostic tool for tokamak plasma. The spatial evolution for several hypothetical plasma conditions was tested. Simulation routines were also run with the plasma parameters (density and temperature profiles) similar to a shot in the Princeton beta experiment modified (PBX-M) tokamak and a shot in Tokamak Fusion Test Reactor tokamak. A comparison between the simulation result and the experimentally obtained data (for each of these two shots) is presented. A good correlation in such comparisons for a number of such shots can establish the accurateness and usefulness of this probe. The result can possibly be extended for other plasma machines and for various plasma conditions in those machines.

  12. Uranium isotope separation using styrene cation exchangers

    International Nuclear Information System (INIS)

    Kahovec, J.

    1980-01-01

    The separation of 235 U and 238 U isotopes is carried out either by simple isotope exchange in the system uranium-cation exchanger (sulphonated styrene divinylbenzene resin), or by combination of isotope exchange in a uranium-cation exchanger (Dowex 50, Amberlite IR-120) system and a chemical reaction. A review is presented of elution agents used, the degree of cation exchanger cross-linking, columns length, and 235 U enrichment. The results are described of the isotope effect study in a U(IV)-U(VI)-cation exchanger system conducted by Japanese and Romanian authors (isotope exchange kinetics, frontal analysis, reverse (indirect) frontal analysis). (H.S.)

  13. Cation-π interactions in structural biology

    OpenAIRE

    Gallivan, Justin P.; Dougherty, Dennis A.

    1999-01-01

    Cation-pi interactions in protein structures are identified and evaluated by using an energy-based criterion for selecting significant sidechain pairs. Cation-pi interactions are found to be common among structures in the Protein Data Bank, and it is clearly demonstrated that, when a cationic sidechain (Lys or Arg) is near an aromatic sidechain (Phe, Tyr, or Trp), the geometry is biased toward one that would experience a favorable cation-pi interaction. The sidechain of Arg is more likely tha...

  14. Simultaneous anion and cation mobility in polypyrrole

    DEFF Research Database (Denmark)

    Skaarup, Steen; Bay, Lasse; Vidanapathirana, K.

    2003-01-01

    and the expulsion of anions; a broad anodic peak centered at ca. - 0.5 V representing the expulsion of cations; and a second broad peak at +0.2 to +0.5 V corresponding to anions being inserted. Although the motion of cations is the most important, as expected, there is a significant anion contribution, thereby...... complicating reproducibility when employing PPy(DBS) polymers as actuators. When the cation is doubly charged, it enters the film less readily, and anions dominate the mobility. Using a large and bulky cation switches the mechanism to apparently total anion motion. The changes in area of the three peaks...

  15. Assaying Cellular Viability Using the Neutral Red Uptake Assay.

    Science.gov (United States)

    Ates, Gamze; Vanhaecke, Tamara; Rogiers, Vera; Rodrigues, Robim M

    2017-01-01

    The neutral red uptake assay is a cell viability assay that allows in vitro quantification of xenobiotic-induced cytotoxicity. The assay relies on the ability of living cells to incorporate and bind neutral red, a weak cationic dye, in lysosomes. As such, cytotoxicity is expressed as a concentration-dependent reduction of the uptake of neutral red after exposure to the xenobiotic under investigation. The neutral red uptake assay is mainly used for hazard assessment in in vitro toxicology applications. This method has also been introduced in regulatory recommendations as part of 3T3-NRU-phototoxicity-assay, which was regulatory accepted in all EU member states in 2000 and in the OECD member states in 2004 as a test guideline (TG 432). The present protocol describes the neutral red uptake assay using the human hepatoma cell line HepG2, which is often employed as an alternative in vitro model for human hepatocytes. As an example, the cytotoxicity of acetaminophen and acetyl salicylic acid is assessed.

  16. Molecular design of high performance fused heteroacene radical cations: A DFT study

    International Nuclear Information System (INIS)

    Kawabata, Hiroshi; Ohmori, Shigekazu; Matsushige, Kazumi; Tachikawa, Hiroto

    2008-01-01

    Hybrid density functional theory (DFT) calculations have been carried out for neutral and radical cation of fused furan oligomer, denoted by F(n) where n means number of furan rings in the oligomer, to elucidate the electronic structures at ground and low-lying excited states. A polymer of fused furan was also investigated using one-dimensional periodic boundary condition (PBC) for comparison. It was found that the reorganization energy of radical cation of F(n) from vertical hole trapping point to its relaxed structure is significantly small. Also, the reorganization energy decreased gradually with increasing n, indicating that F(n) has an effective hole transport property. It was found that the cation radical of F(n) has a low energy band at near IR region, which is strongly correlated to hole conductivity. The relation between the electronic states and hole conductivity was discussed on the basis of theoretical calculations

  17. Infrared Spectroscopy of Matrix-Isolated Polycyclic Aromatic Hydrocarbon Cations. 3. The Polyacenes Anthracene, Tetracene, and Pentacene

    Science.gov (United States)

    Hudgins, D. M.; Allamandola, L. J.

    1995-01-01

    Gaseous, ionized Polycyclic Aromatic Hydrocarbons (PAH's) are thought to be responsible for a very common family of interstellar infrared emission bands. Unfortunately, very little infrared spectroscopic data are available on ionized PAH's. Here we present the near- and mid-infrared spectra of the polyacene cations anthracene, tetracene, and pentacene. We also report the vibrational frequencies and relative intensities of the pentacene anion. The cation bands corresponding to the CC modes are typically about 10-20 times more intense than those of the CH out-of-plane bending vibrations. For the cations the CC stretching and CH in-plane bending modes give rise to bands which are an order of magnitude stronger than for the neutral species, and the CH out-of-plane bends produce bands which are 3-20 times weaker than in the neutral species. This behavior is similar to that found for most other PAH cations. The most intense PAH cation bands fall within the envelopes of the most intense interstellar features. The strongest absorptions in the polyacenes anthracene, tetracene, and pentacene tend to group around 1400 / cm (between about 1340 and 1500 / cm) and near 1180 /cm, regions of only moderate interstellar emission. These very strong polyacene bands tend to fall in gaps in the spectra of the other PAH cations studied to date suggesting that while PAHs with polyacene structures may contribute to specific regions of the interstellar emission spectra, they are not dominant members of the interstellar PAH family.

  18. Infrared Spectroscopy of Matrix-Isolated Polycyclic Aromatic Hydrocarbon Cations. 3; The Polyacenes Anthracene, Tetracence, and Pentacene

    Science.gov (United States)

    Hudgins, D. M.; Allamandola, L. J.

    1995-01-01

    Gaseous, ionized polycyclic aromatic hydrocarbons (PAHS) are thought to be responsible for a very common family of interstellar infrared emission bands. Unfortunately, very little infrared spectroscopic data are available on ionized PAHS. Here we present the near- and mid-infrared spectra of the polyacene cations anthracene, tetracene, and pentacene. We also report the vibrational frequencies and relative intensities of the pentacene anion. The cation bands corresponding to the CC modes are typically about 10-20 times more intense than those of the CH out-of-plane bending vibrations. For the cations the CC stretching and CH in-plane bending modes give rise to bands which are an order of magnitude stronger than for the neutral species, and the CH out-of-plane bends produce bands which are 3-20 times weaker than in the neutral species. This behavior is similar to that found for most other PAH cations. The most intense PAH cation bands fall within the envelopes of the most intense interstellar features. The strongest absorptions in the polyacenes anthracene, tetracene, and pentacene tend to group around 1400/cm (between about 1340 and 1500/cm) and near 1180/cm, regions of only moderate interstellar emission. These very strong polyacene bands tend to fall in gaps in the spectra of the other PAH cations studied to date suggesting that while PAHs with polyacene structures may contribute to specific regions of the interstellar emission spectra, they are not dominant members of the interstellar PAH family.

  19. Afrikaans Syllabification Patterns

    Directory of Open Access Journals (Sweden)

    Tilla Fick

    2010-01-01

    Full Text Available In contrast to English, automatic hyphenation by computer of Afrikaans words is a problem that still needs to be addressed, since errors are still often encountered in printed text. An initial step in this task is the ability to automatically syllabify words. Since new words are created continuously by joining words, it is necessary to develop an “intelligent” technique for syllabification. As a first phase of the research, we consider only the orthographic information of words, and disregard both syntactic and morphological information. This approach allows us to use machine-learning techniques such as artificial neural networks and decision trees that are known for their pattern recognition abilities. Both these techniques are trained with isolated patterns consisting of input patterns and corresponding outputs (or targets that indicate whether the input pattern should be split at a certain position, or not. In the process of compiling a list of syllabified words from which to generate training data for the  syllabification problem, irregular patterns were identified. The same letter patterns are split differently in different words and complete words that are spelled identically are split differently due to meaning. We also identified irregularities in and between  the different dictionaries that we used. We examined the influence range of letters that are involved in irregularities. For example, for their in agter-ente and vaste-rente we have to consider three letters to the left of r to be certain where the hyphen should be inserted. The influence range of the k in verstek-waarde and kleinste-kwadrate is four to the left and three to the right. In an analysis of letter patterns in Afrikaans words we found that the letter e has the highest frequency overall (16,2% of all letters in the word list. The frequency of words starting with s is the highest, while the frequency of words ending with e is the highest. It is important to

  20. Spectroscopy of neutral radium

    Energy Technology Data Exchange (ETDEWEB)

    Mol, Aran; De, Subhadeep; Jungmann, Klaus; Wilschut, Hans; Willmann, Lorenz [KVI, University of Groningen, Groningen (Netherlands)

    2008-07-01

    The heavy alkaline earth atoms radium is uniquely sensitive towards parity and time reversal symmetry violations due to a large enhancement of an intrinsic permanent electric dipole moment of the nucleous or the electron. Furthermore, radium is sensitive to atomic parity violation and the nuclear anapole moment. To prepare such experiments spectroscopy of relevant atomic states need to be done. At a later stage we will build a neutral atom trap for radium. We have built an atomic beam of the short lived isotope {sup 225}Ra with a flux of several 10{sup 4} atoms/sec. We are preparing the laser spectroscopy using this beam setup. In the preparation for efficient laser cooling and trapping we have successfully trapped barium, which is similar in it's requirements for laser cooling. The techniques which we have developed with barium can be used to trap rare radium isotopes. We report on the progress of the experiments.

  1. Review on cation exchange selectivity coefficients for MX-80 bentonite

    International Nuclear Information System (INIS)

    Domenech, C.; Arcos, D.; Duro, L.; Sellin, P.

    2005-01-01

    . From this analyses, it can be concluded that the calculated selectivity coefficients for Ca and Mg (K Ca and K Mg ) increase linearly with the S:L ratio, following an equation of the type K ex = A x (S:L) (g dm -3 ) for a fixed solid dry density. Besides, the value of K ex decreases when increasing the dry density of bentonite. These effects can be related to osmosis. Indeed, the higher the density, the lower the pore size in the interlaminar space. This may increase anion exclusion effects and, therefore, difficult cation diffusion given that the solution must be kept electrically neutral. It must be also highlighted that ionic strength effects can be relevant in any cation exchange process and, therefore, the influence of this parameter on the value of K ex must also be assessed. (authors)

  2. Cationic polymers and their therapeutic potential

    NARCIS (Netherlands)

    Samal, S.K.; Dash, M.; van Vlierberghe, S.; Kaplan, D.; Chiellini, E.; van Blitterswijk, Clemens; Moroni, Lorenzo; Dubruel, P.

    2012-01-01

    The last decade has witnessed enormous research focused on cationic polymers. Cationic polymers are the subject of intense research as non-viral gene delivery systems, due to their flexible properties, facile synthesis, robustness and proven gene delivery efficiency. Here, we review the most recent

  3. Tripodal Receptors for Cation and Anion Sensors

    Directory of Open Access Journals (Sweden)

    David N. Reinhoudt

    2006-08-01

    Full Text Available This review discusses different types of artificial tripodal receptors for the selectiverecognition and sensing of cations and anions. Examples on the relationship between structure andselectivity towards cations and anions are described. Furthermore, their applications as potentiometricion sensing are emphasised, along with their potential applications in optical sensors or optodes.

  4. Asymmetric Aminalization via Cation-Binding Catalysis

    DEFF Research Database (Denmark)

    Park, Sang Yeon; Liu, Yidong; Oh, Joong Suk

    2018-01-01

    Asymmetric cation-binding catalysis, in principle, can generate "chiral" anionic nucleophiles, where the counter cations are coordinated within chiral environments. Nitrogen-nucleophiles are intrinsically basic, therefore, its use as nucleophiles is often challenging and limiting the scope of the...

  5. The adsorption of helium atoms on small cationic gold clusters.

    Science.gov (United States)

    Goulart, Marcelo; Gatchell, Michael; Kranabetter, Lorenz; Kuhn, Martin; Martini, Paul; Gitzl, Norbert; Rainer, Manuel; Postler, Johannes; Scheier, Paul; Ellis, Andrew M

    2018-04-04

    Adducts formed between small gold cluster cations and helium atoms are reported for the first time. These binary ions, Aun+Hem, were produced by electron ionization of helium nanodroplets doped with neutral gold clusters and were detected using mass spectrometry. For a given value of n, the distribution of ions as a function of the number of added helium atoms, m, has been recorded. Peaks with anomalously high intensities, corresponding to so-called magic number ions, are identified and interpreted in terms of the geometric structures of the underlying Aun+ ions. These features can be accounted for by planar structures for Aun+ ions with n ≤ 7, with the addition of helium having no significant effect on the structures of the underlying gold cluster ions. According to ion mobility studies and some theoretical predictions, a 3-D structure is expected for Au8+. However, the findings for Au8+ in this work are more consistent with a planar structure.

  6. Structural and energetic study of cation-π-cation interactions in proteins.

    Science.gov (United States)

    Pinheiro, Silvana; Soteras, Ignacio; Gelpí, Josep Lluis; Dehez, François; Chipot, Christophe; Luque, F Javier; Curutchet, Carles

    2017-04-12

    Cation-π interactions of aromatic rings and positively charged groups are among the most important interactions in structural biology. The role and energetic characteristics of these interactions are well established. However, the occurrence of cation-π-cation interactions is an unexpected motif, which raises intriguing questions about its functional role in proteins. We present a statistical analysis of the occurrence, composition and geometrical preferences of cation-π-cation interactions identified in a set of non-redundant protein structures taken from the Protein Data Bank. Our results demonstrate that this structural motif is observed at a small, albeit non-negligible frequency in proteins, and suggest a preference to establish cation-π-cation motifs with Trp, followed by Tyr and Phe. Furthermore, we have found that cation-π-cation interactions tend to be highly conserved, which supports their structural or functional role. Finally, we have performed an energetic analysis of a representative subset of cation-π-cation complexes combining quantum-chemical and continuum solvation calculations. Our results point out that the protein environment can strongly screen the cation-cation repulsion, leading to an attractive interaction in 64% of the complexes analyzed. Together with the high degree of conservation observed, these results suggest a potential stabilizing role in the protein fold, as demonstrated recently for a miniature protein (Craven et al., J. Am. Chem. Soc. 2016, 138, 1543). From a computational point of view, the significant contribution of non-additive three-body terms challenges the suitability of standard additive force fields for describing cation-π-cation motifs in molecular simulations.

  7. Net neutrality and audiovisual services

    OpenAIRE

    van Eijk, N.; Nikoltchev, S.

    2011-01-01

    Net neutrality is high on the European agenda. New regulations for the communication sector provide a legal framework for net neutrality and need to be implemented on both a European and a national level. The key element is not just about blocking or slowing down traffic across communication networks: the control over the distribution of audiovisual services constitutes a vital part of the problem. In this contribution, the phenomenon of net neutrality is described first. Next, the European a...

  8. LADEE Neutral Mass Spectrometer Data

    Data.gov (United States)

    National Aeronautics and Space Administration — This bundle contains the data collected by the Neutral Mass Spectrometer (NMS) instrument aboard the Lunar Atmosphere and Dust Environment Explorer (LADEE)...

  9. Phenomenology of neutral current interactions

    International Nuclear Information System (INIS)

    Sakurai, J.J.

    1978-01-01

    Neutral-current interactions are discussed within a rather general phenomenological framework without commitment to any particular theoretical model. Three points are kept in mind: what various experiments really measure; the performing of complete experiments to determine the neutral-current couplings; and the testing of models in an objective, emotionally uninvolved manner. The following topics are considered: neutrino-electron scattering, hadronic currents and models, neutrino-induced inclusive hadronic reactions, neutrino-induced exclusive hadronic reactions, and neutral-current phenomena without neutrinos. In conclusion, what has actually been learned about neutral-current interactions is summarized. 9 figures, 2 tables

  10. On becoming neutral: effects of experimental neutralizing reconsidered.

    Science.gov (United States)

    van den Hout, M; van Pol, M; Peters, M

    2001-12-01

    Behaviour Research and Therapy 34 (1996) 889-898 found that writing out a negative thought produced anxiety and an urge to neutralize the thought, that instructing participants to neutralize the thought reduced anxiety/neutralization urge in the short run (i.e. within 2 min), but that in the control group 20 min without instruction was attended by the same reduction in anxiety/urge to neutralize ("natural decay"). The observations were made with pariticipants who scored high on "thought action fusion" and the experiment was set up as exerimental model of obsessions. We repeated the study with participants that were not selected on thought action fusion. All the findings reported by Behaviour Research and Therapy 34 (1996) 889-898 were replicated. Correlational analysis indicated that the strength of the effect was not related to scores on scales measuring "thought action fusion". Behaviour Research and Therapy 34 (1996) 889-898 did not assess whether non-neutralizing was followed by immediate reductions in distress. We did assess this and found that the larger part of the immediate reduction of distress after neutralization also occurs when no neutralization instruction is given. The effects of neutralization instructions in the present type of experiment are considerably less powerful than suggested earlier.

  11. Characterization of cationic glycoporphyrins by electrospray tandem mass spectrometry.

    Science.gov (United States)

    Silva, Eduarda M P; Serra, Vanda Vaz; Ribeiro, Anderson O; Tomé, João P C; Domingues, Pedro; Faustino, M Amparo F; Neves, M Graça P M S; Tomé, Augusto C; Cavaleiro, José A S; Ferrer-Correia, António J; Iamamoto, Yassuko; Domingues, M Rosário M

    2006-01-01

    Novel cationic porphyrin derivatives having a galactose or a bis(isopropylidene)galactose unit linked directly to a pyridine or to an aminophenyl group were characterized by electrospray tandem mass spectrometry (ESI-MS/MS). The electrospray mass spectra (ESI-MS) show the M(+) ions, since these porphyrins are already monocharged in solution. The fragmentation of these ions under ESI-MS/MS conditions was studied and it was found that elimination of the sugar residue as a radical (-163 or -243 Da) is a common fragmentation pathway. Loss of the sugar unit as a neutral fragment (-162 or -242 Da) and cross-ring fragmentations typical of glyco-derivatives are also observed for the pyridinium glycoporphyrins, but they are absent in the case of ammonium glycoporphyrins. The cationic beta-pyridiniumvinyl porphyrins show an atypical fragmentation due to the cleavage of the C(5)-C(6) bond of the sugar unit. Overall, the different patterns of fragmentation observed in the ESI-MS/MS spectra of the sugar pyridinium porphyrins and of the sugar ammonium phenyl porphyrins can give important information about the type of spacer between the porphyrin and the sugar unit. Copyright (c) 2006 John Wiley & Sons, Ltd.

  12. The adsorption of helium atoms on coronene cations

    Energy Technology Data Exchange (ETDEWEB)

    Kurzthaler, Thomas; Rasul, Bilal; Kuhn, Martin; Scheier, Paul, E-mail: Paul.Scheier@uibk.ac.at, E-mail: andrew.ellis@le.ac.uk [Institut für Ionenphysik und Angewandte Physik, Universität Innsbruck, Technikerstr. 25, A-6020 Innsbruck (Austria); Lindinger, Albrecht [Institut für Experimentalphysik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin (Germany); Ellis, Andrew M., E-mail: Paul.Scheier@uibk.ac.at, E-mail: andrew.ellis@le.ac.uk [Department of Chemistry, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom)

    2016-08-14

    We report the first experimental study of the attachment of multiple foreign atoms to a cationic polycyclic aromatic hydrocarbon (PAH). The chosen PAH was coronene, C{sub 24}H{sub 12}, which was added to liquid helium nanodroplets and then subjected to electron bombardment. Using mass spectrometry, coronene cations decorated with helium atoms were clearly seen and the spectrum shows peaks with anomalously high intensities (“magic number” peaks), which represent ion-helium complexes with added stability. The data suggest the formation of a rigid helium layer consisting of 38 helium atoms that completely cover both faces of the coronene ion. Additional magic numbers can be seen for the further addition of 3 and 6 helium atoms, which are thought to attach to the edge of the coronene. The observation of magic numbers for the addition of 38 and 44 helium atoms is in good agreement with a recent path integral Monte Carlo prediction for helium atoms on neutral coronene. An understanding of how atoms and molecules attach to PAH ions is important for a number of reasons including the potential role such complexes might play in the chemistry of the interstellar medium.

  13. Coordination phenomena of cationic uranium(iv) complexes

    International Nuclear Information System (INIS)

    Rohwer, H.E.

    1974-12-01

    The coordination properties of the cationic uranium(IV) complexes UCl 3 + , UCl 2 2+ , UCl 3+ , and U 4+ were studied in a non-aqueous medium in the presence of perchlorate as counterion which, however, proved to coordinate to a much greater extent than expected. The strong neutral ligand, HMPA, could successively displace some of the perchlorates. An electrostatic model for the U(CIO 4 ) 4 -HMPA-acetone system compared favourably with the actual results. This emphasized the high ionic content in the bonding with actenoid cations, even with such a high charge as +4 . These conclusions are in agreement with studies 75 in which nitrate acts as counter ion. Correspondingly the uranium (IV) chemistry is characterized by the absence of typical 3d-organometallic chemistry, for example, strong bonding with CO, P(Phi) 3 etc, which strongly depends on covalent bonding. This stresses the fact that the d and f orbitals are not readily available for strong bond formation with the actenoids. 76

  14. Exploring backbone-cation alkyl spacers for multi-cation side chain anion exchange membranes

    Science.gov (United States)

    Zhu, Liang; Yu, Xuedi; Hickner, Michael A.

    2018-01-01

    In order to systematically study how the arrangement of cations on the side chain and length of alkyl spacers between cations impact the performance of multi-cation AEMs for alkaline fuel cells, a series of polyphenylene oxide (PPO)-based AEMs with different cationic side chains were synthesized. This work resulted in samples with two or three cations in a side chain pendant to the PPO backbone. More importantly, the length of the spacer between cations varied from 3 methylene (-CH2-) (C3) groups to 8 methylene (C8) groups. The highest conductivity, up to 99 mS/cm in liquid water at room temperature, was observed for the triple-cation side chain AEM with pentyl (C5) or hexyl (C6) spacers. The multi-cation AEMs were found to have decreased water uptake and ionic conductivity when the spacer chains between cations were lengthened from pentyl (C5) or hexyl (C6) to octyl (C8) linking groups. The triple-cation membranes with pentyl (C5) or hexyl (C6) groups between cations showed greatest stability after immersion in 1 M NaOH at 80 °C for 500 h.

  15. CO2-neutral fuels

    Directory of Open Access Journals (Sweden)

    Goede A. P. H.

    2015-01-01

    Full Text Available The need for storage of renewable energy (RE generated by photovoltaic, concentrated solar and wind arises from the fact that supply and demand are ill-matched both geographically and temporarily. This already causes problems of overcapacity and grid congestion in countries where the fraction of RE exceeds the 20% level. A system approach is needed, which focusses not only on the energy source, but includes conversion, storage, transport, distribution, use and, last but not least, the recycling of waste. Furthermore, there is a need for more flexibility in the energy system, rather than relying on electrification, integration with other energy systems, for example the gas network, would yield a system less vulnerable to failure and better adapted to requirements. For example, long-term large-scale storage of electrical energy is limited by capacity, yet needed to cover weekly to seasonal demand. This limitation can be overcome by coupling the electricity net to the gas system, considering the fact that the Dutch gas network alone has a storage capacity of 552 TWh, sufficient to cover the entire EU energy demand for over a month. This lecture explores energy storage in chemicals bonds. The focus is on chemicals other than hydrogen, taking advantage of the higher volumetric energy density of hydrocarbons, in this case methane, which has an approximate 3.5 times higher volumetric energy density. More importantly, it allows the ready use of existing gas infrastructure for energy storage, transport and distribution. Intermittent wind electricity generated is converted into synthetic methane, the Power to Gas (P2G scheme, by splitting feedstock CO2 and H2O into synthesis gas, a mixture of CO and H2. Syngas plays a central role in the synthesis of a range of hydrocarbon products, including methane, diesel and dimethyl ether. The splitting is accomplished by innovative means; plasmolysis and high-temperature solid oxygen electrolysis. A CO2-neutral fuel

  16. Stilbene dimer radical cations in the radiolyses of stilbenes and 1,2,3,4-tetraphenylcyclobutanes

    International Nuclear Information System (INIS)

    Tojo, Sachiko; Morishima, Kazuhiro; Ishida, Akito; Majima, Tetsuro; Takamuku, Setsuo

    1995-01-01

    The reaction of the stilbene radical cation formed by pulse radiolysis or γ-radiolyses is explained based on neutralization as well as the formation of a π-type stilbene dimer radical cation (π-St 2 +· ), converting to the σ-type St 2 +· (σ-St 2 +· ). The r-1, c-2, t-3, t-4-tetraphenylcyclobutane radical cation generated in a rigid matrix at 77 K which converted to σ-St 2 +· upon warming. Both r-1, c-2, t-3, t-4- and r-1, t-2, c-3, t-4-tetraphenylcyclobutane radical cations underwent photochemical cycloreversion to π-St 2 +· upon irradiation at wavelengths longer than 390 nm at 77 K, and converted to σ-St 2 +· upon warming. It is suggested that π-St 2 +· has overlapping arrangements of π-electrons, while σ-St 2 +· has radical and cation centers on the 1- and 4-positions of the C 4 linkage. (author)

  17. Novel Reactivity Of The Cationic Complex

    International Nuclear Information System (INIS)

    Wang, J.; Dash, A.K.; Eisen, AM.; Berthet, J.C.; Ephritikhine, M.

    2002-01-01

    The catalytic chemistry of electrophilic d 0 /f organometallic complexes is nowadays under intense investigation, reaching a high level of sophistication. General aspects concerning these complexes are concentrated for most studies to the functionalization of unsaturated organic molecules. To cite an instance, the actinide-promoted oligomerization of terminal alkynes is of essential present concern since it may introduce to a diversity of organic enynes and oligoacetylene products that are valuable synthons for the synthesis of natural products. Enynes are the simplest oligomerization products of alkynes. We have demonstrated that organoactinides complexes of the type [Cp* 2 AnMe 2 AnMe 2 ] (Cp* = C 5 Me 5 ; An = U, Th) are active catalysts for the linear oligomerization of terminal alkynes and the extent of oligomerization was found to be strongly dependent on the electronic and steric properties of the alkyne substituents. Bulky alkynes were reacted with high regioselectivity toward dimer and/or trimers whereas for non-bulky alkynes, these compounds were transformed into oligomers with a total deficiency of regioselectivity. The addition of primary amines to the catalytic cycle, for An = Th, granted the chemoselective formation of dimers, chemoselectively, whereas for An = U, this control was not succeeded. In distinction to the neutral organoactinide complexes, homogeneous cationic d 0 /f n actinide complexes have been used as in the homogeneous polymerization of olefins as extremely active catalysts. Hence, the catalytic alkyne oligomerization is a opportune route to explore insertions and σ-bond metathesis reactivity of complexes. We have recently shown that the reaction of terminal alkynes (RC≡CH), promoted by [(Et 2 N) 3 U][BPh 4 ], in toluene, produces efficiently mostly the gem dimers (for R = Me, i Pr and n Bu) as the major products, whereas for bulky alkynes (R = t MS or t Bu) small amounts of the cis dimer was concomitantly obtained. A plausible

  18. Electromagnetic radiation optimum neutralizer

    International Nuclear Information System (INIS)

    Smirnov, Igor

    2002-01-01

    This particular article relates to subtle electrical effects, and provides some evidence of a fundamental nature on how subtle low frequency electromagnetic fields might be utilized to protect human body against harmful effects of high frequencies electromagnetic radiation. I have focused my efforts on definite polar polymer compound named EMRON which is patented in the USA. This polar polymer compound can be excited by external high frequencies electromagnetic fields to generate subtle low frequency oscillations that are beneficial for cellular life structures. This concept is based on the possibility of existence of resonance phenomenon between polar polymers and biopolymers such as proteins, nucleic acids, lipids, etc. Low frequency patterns generated by defined polar polymer compound can interact with biostructures and transmit the signals that support and improve cellular functions in the body. The mechanism of this process was confirmed by number of studies. The animal (including human) brain is affected by electromagnetic waves to the extent that production of Alpha or Theta waves can be directly induced into brain by carrying an ELF (extremely low frequency, 5-12 Hz) signal on a microwave carrier frequency. EMRON does not reduce the power of electromagnetic fields. It 'shields' the cellular structures of the body against the harmful effects of EMR. The radiation is still entering the body but the neutralizing effect of EMRON renders the radiation harmless

  19. Is science metaphysically neutral?

    Science.gov (United States)

    Fry, Iris

    2012-09-01

    This paper challenges the claim that science is metaphysically neutral upheld by contenders of the separation of peacefully co-existent science and religion and by evolutionary theists. True, naturalistic metaphysical claims can neither be refuted nor proved and are thus distinct from empirical hypotheses. However, metaphysical assumptions not only regulate the theoretical and empirical study of nature, but are increasingly supported by the growing empirical body of science. This historically evolving interaction has contributed to the development of a naturalistic worldview that renounces the necessity of a transcendent god and of purposeful design. The thesis presented here differs not only from the claims of the "separatists" and of evolutionary theists. In pointing to the metaphysical aspects of science, I also criticize the failure of some evolutionary naturalists to distinguish between empirical and metaphysical contentions. Most important, based on the examination of science suggested here, creationists' false accusation that science is only a naturalistic dogma is refuted. Finally, the difficulties involved in the position endorsed here for the public support of evolution are acknowledged, taking into account the high religious profile of the American society and the social and political context in the US and in other countries. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Search for an explanation for neutralization rates of atomic ion-ion reactions

    Science.gov (United States)

    Miller, Thomas M.; Wiens, Justin P.; Shuman, Nicholas S.; Viggiano, Albert A.

    2016-09-01

    We have measured well over a hundred rate coefficients k for cation-anion mutual neutralization reactions at thermal energies. For molecular ions, the k at 300 K tend not to vary more than a factor of two or three, presumably because a great many neutral states cross the incoming Coulombic potential energy curve. Atomic-atomic systems, for which there are few favorable curve crossings between the neutral and Coulombic curves, show variation of at least a factor of 60 in the measured k values at 300 K. For reactions involving the noble-gas cations, we assume that the final state is the lowest excited state of the neutral, plus the ground state of the neutralized anion, because otherwise the crossing distance R is so small that the curve-crossing probability is nil. We plotted measured k values (in cm3/s) vs the distance R (in bohr) at which the neutral and Coulombic curves cross, the found that the data are fairly well fit by a power law for k, 10-4R - 2 . 8 . The question is, is there a physical explanation for the observed dependence on R? We will discuss the data and the expectations of Landau-Zener theory. Supported by Air Force Office of Scientific Research (AFOSR-2303EP).

  1. Cationic Bolaamphiphiles for Gene Delivery

    Science.gov (United States)

    Tan, Amelia Li Min; Lim, Alisa Xue Ling; Zhu, Yiting; Yang, Yi Yan; Khan, Majad

    2014-05-01

    Advances in medical research have shed light on the genetic cause of many human diseases. Gene therapy is a promising approach which can be used to deliver therapeutic genes to treat genetic diseases at its most fundamental level. In general, nonviral vectors are preferred due to reduced risk of immune response, but they are also commonly associated with low transfection efficiency and high cytotoxicity. In contrast to viral vectors, nonviral vectors do not have a natural mechanism to overcome extra- and intracellular barriers when delivering the therapeutic gene into cell. Hence, its design has been increasingly complex to meet challenges faced in targeting of, penetration of and expression in a specific host cell in achieving more satisfactory transfection efficiency. Flexibility in design of the vector is desirable, to enable a careful and controlled manipulation of its properties and functions. This can be met by the use of bolaamphiphile, a special class of lipid. Unlike conventional lipids, bolaamphiphiles can form asymmetric complexes with the therapeutic gene. The advantage of having an asymmetric complex lies in the different purposes served by the interior and exterior of the complex. More effective gene encapsulation within the interior of the complex can be achieved without triggering greater aggregation of serum proteins with the exterior, potentially overcoming one of the great hurdles faced by conventional single-head cationic lipids. In this review, we will look into the physiochemical considerations as well as the biological aspects of a bolaamphiphile-based gene delivery system.

  2. The merits of neutral theory

    NARCIS (Netherlands)

    Alonso, D.; Etienne, R.S.; McKane, A.J.

    2006-01-01

    Hubbell's neutral theory of biodiversity has challenged the classic niche-based view of ecological community structure. Although there have been many attempts to falsify Hubbell's theory, we argue that falsification should not lead to rejection, because there is more to the theory than neutrality

  3. Neutral evolution of mutational robustness

    NARCIS (Netherlands)

    Nimwegen, Erik van; Crutchfield, James P.; Huynen, Martijn

    1999-01-01

    We introduce and analyze a general model of a population evolving over a network of selectively neutral genotypes. We show that the population s limit distribution on the neutral network is solely determined by the network topology and given by the principal eigenvector of the network

  4. Net neutrality and audiovisual services

    NARCIS (Netherlands)

    van Eijk, N.; Nikoltchev, S.

    2011-01-01

    Net neutrality is high on the European agenda. New regulations for the communication sector provide a legal framework for net neutrality and need to be implemented on both a European and a national level. The key element is not just about blocking or slowing down traffic across communication

  5. Stressor states and the cation crossroads.

    Science.gov (United States)

    Weber, Karl T; Bhattacharya, Syamal K; Newman, Kevin P; Soberman, Judith E; Ramanathan, Kodangudi B; McGee, Jesse E; Malik, Kafait U; Hickerson, William L

    2010-12-01

    Neurohormonal activation involving the hypothalamic-pituitary-adrenal axis and adrenergic nervous and renin-angiotensin-aldosterone systems is integral to stressor state-mediated homeostatic responses. The levels of effector hormones, depending upon the degree of stress, orchestrate the concordant appearance of hypokalemia, ionized hypocalcemia and hypomagnesemia, hypozincemia, and hyposelenemia. Seemingly contradictory to homeostatic responses wherein the constancy of extracellular fluid would be preserved, upregulation of cognate-binding proteins promotes coordinated translocation of cations to injured tissues, where they participate in wound healing. Associated catecholamine-mediated intracellular cation shifts regulate the equilibrium between pro-oxidants and antioxidant defenses, a critical determinant of cell survival. These acute and chronic stressor-induced iterations in extracellular and intracellular cations are collectively referred to as the cation crossroads. Intracellular cation shifts, particularly excessive accumulation of Ca2+, converge on mitochondria to induce oxidative stress and raise the opening potential of their inner membrane permeability transition pores (mPTPs). The ensuing loss of cationic homeostasis and adenosine triphosphate (ATP) production, together with osmotic swelling, leads to organellar degeneration and cellular necrosis. The overall impact of iterations in extracellular and intracellular cations and their influence on cardiac redox state, cardiomyocyte survival, and myocardial structure and function are addressed herein.

  6. Fluoride ion recognition by chelating and cationic boranes.

    Science.gov (United States)

    Hudnall, Todd W; Chiu, Ching-Wen; Gabbaï, François P

    2009-02-17

    Because of the ubiquity of fluoride ions and their potential toxicity at high doses, researchers would like to design receptors that selectively detect this anion. Fluoride is found in drinking water, toothpaste, and osteoporosis drugs. In addition, fluoride ions also can be detected as an indicator of uranium enrichment (via hydrolysis of UF(6)) or of the chemical warfare agent sarin, which releases the ion upon hydrolysis. However, because of its high hydration enthalpy, the fluoride anion is one of the most challenging targets for anion recognition. Among the various recognition strategies that are available, researchers have focused a great deal of attention on Lewis acidic boron compounds. These molecules typically interact with fluoride anions to form the corresponding fluoroborate species. In the case of simple triarylboranes, the fluoroborates are formed in organic solvents but not in water. To overcome this limitation, this Account examines various methods we have pursued to increase the fluoride-binding properties of boron-based receptors. We first considered the use of bifunctional boranes, which chelate the fluoride anion, such as 1,8-diborylnaphthalenes or heteronuclear 1-boryl-8-mercurio-naphthalenes. In these molecules, the neighboring Lewis acidic atoms can cooperatively interact with the anionic guest. Although the fluoride binding constants of the bifunctional compounds exceed those of neutral monofunctional boranes by several orders of magnitude, the incompatibility of these systems with aqueous media limits their utility. More recently, we have examined simple triarylboranes whose ligands are decorated by cationic ammonium or phosphonium groups. These cationic groups increase the electrophilic character of these boranes, and unlike their neutral analogs, they are able to complex fluoride in aqueous media. We have also considered cationic boranes, which form chelate complexes with fluoride anions. Our work demonstrates that Coulombic and chelate

  7. Carbon monoxide migratory insertion - A comparison of cationic and neutral palladium(II) complexes

    International Nuclear Information System (INIS)

    Frankcombe, K.; Cavell, K.J.; Yates, B.F.; Knott, R.B.

    1998-01-01

    With the use of ANSTO's resources and expertise and with support from AINSE, we have carried out extensive computer modelling on the mechanism of the palladium catalysed carbonylation reaction, a process which is used industrially in the conversion of carbon monoxide into biodegradable polymers. In this project, experimental and theoretical work has focussed on using Pd(II) complexes containing pyridine carboxylate ligands (NC 5 H 4 COO ) to explore the fundamental mechanistic steps. The results for subsequent steps in the catalytic cycle are presented and their implication for the design of more efficient catalysts are discussed

  8. Matrix diffusion of simple cations, anions, and neutral species in fractured crystalline rocks

    International Nuclear Information System (INIS)

    Sato, Haruo

    1999-01-01

    The diffusion of radionuclides into the pore spaces of a rock matrix and the pore properties in fractured crystalline rocks were studied. The work concentrated on the predominant water-conducting fracture system in the host granodiorite of the Kamaishi In Situ Test Site, which consists of fracture fillings and altered grandodiorite. Through-diffusion experiments to obtain effective and apparent diffusion coefficients (De and Da, respectively) for Na + , Cs + , HTO, Cl - , and SeO 3 2- as a function of ionic charge were conducted through the fracture fillings and altered and intact granodiorite. The total porosity φ, density, pore-size distribution, and specific surface area of the pores of the rocks were also determined by a water saturation method and Hg porosimetry. The average φ is, in the order from highest to lowest, as follows: fracture fillings (5.6%) greater than altered granodiorite (3.2%) greater than intact granodiorite (2.3%), and gradually it decreases into the matrix. The pore sizes of the intact and altered granodiorite range from 10 nm to 200 microm, and the fracture fillings from 50 nm to 200 microm, but almost all pores are found around 0.1 and 200 microm in the fracture fillings. The De values for all species are in the following order: fracture fillings greater than altered granodiorite greater than intact granodiorite, as with the rock porosity. In addition. no effect of ionic charge on De is found. No significant dependence for Da values on the rock porosity is found. The formation factors FF and geometric factors G of the rocks were evaluated by normalizing the free water diffusion coefficient Do for each species. The FF decreased with decreasing rock porosity, and an empirical equation for the rock porosity was derived to be FF = φ 1.57±0.02 . The G values showed a tendency to slightly decrease with decreasing rock porosity, but they were approximately constant (0.12 to 0.19) in this porosity range. This indicates that accessible pores decrease into the rock matrix from the fractures, and diffusion is also reduced into the rock matrix. Furthermore, it was concluded that a simplified model based on FF and Do values is approximately reasonable to predict De

  9. Neutral, anionic, cationic, and zwitterionic diblock copolymers featuring poly(2-methoxyethyl acrylate) hydrophobic segments

    DEFF Research Database (Denmark)

    Javakhishvili, Irakli; Jankova Atanasova, Katja; Hvilsted, Søren

    2013-01-01

    -b-PDMAEMA while the betainisation of the latter provides zwitterionic diblock amphiphile PMEA-b-PDMAPS. Inspection of these macromolecular architectures by NMR spectroscopy and size exclusion chromatography (SEC) confirms a fairly high degree of control over the reactions emphasizing flexibility and precision...

  10. Cation distributions on rapidly solidified cobalt ferrite

    Science.gov (United States)

    De Guire, Mark R.; Kalonji, Gretchen; O'Handley, Robert C.

    1990-01-01

    The cation distributions in two rapidly solidified cobalt ferrites have been determined using Moessbauer spectroscopy at 4.2 K in an 8-T magnetic field. The samples were obtained by gas atomization of a Co0-Fe2O3-P2O5 melt. The degree of cation disorder in both cases was greater than is obtainable by cooling unmelted cobalt ferrite. The more rapidly cooled sample exhibited a smaller departure from the equilibrium cation distribution than did the more slowly cooled sample. This result is explained on the basis of two competing effects of rapid solidification: high cooling rate of the solid, and large undercooling.

  11. Radioimmunoassay of human eosinophil cationic protein

    International Nuclear Information System (INIS)

    Venge, P.; Roxin, L.E.; Olsson, I.

    1977-01-01

    A radioimmunosorbent assay has been developed which allows the detection in serum of a cationic protein derived from eosinophil granulocytes. In 34 healthy individuals the mean level was 31 μg/l. with a range of 5 to 55 μg/l. The serum concentration of 'eosinophil' cationic protein was correlated (P<0.001) to the number of eosinophil granulocytes in peripheral blood. Quantitiation of 'eosinophil' cationic protein in serum might be useful in the study of eosinophil granulocyte turnover and function in vivo. (author)

  12. Ferrocene-based diradicals of imino nitroxide, nitronyl nitroxide and verdazyl, and their cations are possible SMM: A quantum chemical study

    Science.gov (United States)

    Pal, Arun K.; Datta, Sambhu N.

    2017-05-01

    Six diradicals designed from imino nitroxide, verdazyl and nitronyl nitroxide monoradicals coupled via the ferrocene moiety and six corresponding triradical cations are quantum chemically investigated. The transoid conformation is employed for considerations of general stability. All biradicals are found as very weakly and antiferromagnetically coupled. This agrees with experiment. The cations have strong antiferromagnetic spin-coupling. The charge and spin population distributions, spin alternation pattern, and the disjoint nature of SOMOs can be used to explain the nature and extent of magnetic interaction. Calculated EPR characteristics identify the neutral species as well as their cations as possible single molecule magnets.

  13. Synthesis of some (eta-arene)dihydridorhenium cations and their reactions with LiAlH4 and LiAlD4

    International Nuclear Information System (INIS)

    Baudrey, D.; Boydell, P.; Ephritikhine, M.

    1986-01-01

    A series of cations [Re(eta-arene)H 2 (PPh 3 ) 2 ] + (arene benzene, toluene, p-xylene, or mesitylene) was prepared from the corresponding neutral dihydridocyclohexadienyl complexes by treatment with CPh 3 BF 4 . These cations reacted with LiAlH 4 and LiAlD 4 to form dihydridocyclohexadienyl complexes. The unusual selectivity of the hydride attack is explained by steric interactions between the ring methyl groups and the bulky phosphine ligands. The initial product of the reaction of the eta-mesitylene cation with LiAlD 4 allows the isomerisation mechanism for the cyclohexadienyl complexes to be clarified. (author)

  14. Cationization of heparin for film applications

    Czech Academy of Sciences Publication Activity Database

    Šimkovic, I.; Mendichi, R.; Kelnar, Ivan; Filip, J.; Hricovíni, M.

    2015-01-01

    Roč. 115, 22 January (2015), s. 551-558 ISSN 0144-8617 Institutional support: RVO:61389013 Keywords : heparin * cationization * NMR Subject RIV: CD - Macromolecular Chemistry Impact factor: 4.219, year: 2015

  15. Is an inequality-neutral flat tax reform really neutral?

    OpenAIRE

    Juan Prieto Rodríguez; Juan Gabriel Rodríguez; Rafael Salas

    2004-01-01

    . Let us assume a revenue- and inequality-neutral flat tax reform shifting from a graduated-rate tax. Is this reform really neutral in terms of the income distribution? Traditionally, there has been a bias toward the inequality analysis, forgetting other relevant aspects of the income distribution. This kind of reforms implies a set of composite transfers, both progressive and regressive, even though inequality remains unchanged. This paper shows that polarization is a useful tool for charact...

  16. Test procedure for cation exchange chromatography

    International Nuclear Information System (INIS)

    Cooper, T.D.

    1994-01-01

    The purpose of this test plan is to demonstrate the synthesis of inorganic antimonate ion exchangers and compare their performance against the standard organic cation exchangers. Of particular interest is the degradation rate of both inorganic and organic cation exchangers. This degradation rate will be tracked by determining the ion exchange capacity and thermal stability as a function of time, radiation dose, and chemical reaction

  17. Cycloaliphatic epoxide resins for cationic UV - cure

    International Nuclear Information System (INIS)

    Verschueren, K.; Balwant Kaur

    1999-01-01

    This paper introduces the cyclo - aliphatic epoxide resins used for the various applications of radiation curing and their comparison with acrylate chemistry. Radiation curable coatings and inks are pre - dominantly based on acrylate chemistry but over the last few years, cationic chemistry has emerged successfully with the unique properties inherent with cyclo - aliphatic epoxide ring structures. Wide variety of cationic resins and diluents, the formulation techniques to achieve the desired properties greatly contributes to the advancement of UV - curing technology

  18. Chemical reactivity of cation-exchanged zeolites

    OpenAIRE

    Pidko, E.A.

    2008-01-01

    Zeolites modified with metal cations have been extensively studied during the last two decades because of their wide application in different technologically important fields such as catalysis, adsorption and gas separation. Contrary to the well-understood mechanisms of chemical reactions catalyzed by Brønsted acid sites in the hydrogen forms of zeolites, the nature of chemical reactivity, and related, the structure of the metal-containing ions in cation-exchanged zeolites remains the subject...

  19. Restructuring of a peat in interaction with multivalent cations: effect of cation type and aging time.

    Science.gov (United States)

    Kunhi Mouvenchery, Yamuna; Jaeger, Alexander; Aquino, Adelia J A; Tunega, Daniel; Diehl, Dörte; Bertmer, Marko; Schaumann, Gabriele Ellen

    2013-01-01

    It is assumed to be common knowledge that multivalent cations cross-link soil organic matter (SOM) molecules via cation bridges (CaB). The concept has not been explicitly demonstrated in solid SOM by targeted experiments, yet. Therefore, the requirements for and characteristics of CaB remain unidentified. In this study, a combined experimental and molecular modeling approach was adopted to investigate the interaction of cations on a peat OM from physicochemical perspective. Before treatment with salt solutions of Al(3+), Ca(2+) or Na(+), respectively, the original exchangeable cations were removed using cation exchange resin. Cation treatment was conducted at two different values of pH prior to adjusting pH to 4.1. Cation sorption is slower (>2 h) than deprotonation of functional groups (cation addition and decreased with increasing cation valency. Sorption coefficients were similar for all cations and at both pH. This contradicts the general expectations for electrostatic interactions, suggesting that not only the interaction chemistry but also spatial distribution of functional groups in OM determines binding of cations in this peat. The reaction of contact angle, matrix rigidity due to water molecule bridges (WaMB) and molecular mobility of water (NMR analysis) suggested that cross-linking via CaB has low relevance in this peat. This unexpected finding is probably due to the low cation exchange capacity, resulting in low abundance of charged functionalities. Molecular modeling demonstrates that large average distances between functionalities (∼3 nm in this peat) cannot be bridged by CaB-WaMB associations. However, aging strongly increased matrix rigidity, suggesting successive increase of WaMB size to connect functionalities and thus increasing degree of cross-linking by CaB-WaMB associations. Results thus demonstrated that the physicochemical structure of OM is decisive for CaB and aging-induced structural reorganisation can enhance cross-link formation.

  20. Characterizing Peptide Neutral Losses Induced by Negative Electron-Transfer Dissociation (NETD)

    Science.gov (United States)

    Rumachik, Neil G.; McAlister, Graeme C.; Russell, Jason D.; Bailey, Derek J.; Wenger, Craig D.; Coon, Joshua J.

    2012-01-01

    We implemented negative electron-transfer dissociation (NETD) on a hybrid ion trap/Orbitrap mass spectrometer to conduct ion/ion reactions using peptide anions and radical reagent cations. In addition to sequence-informative ladders of a•- and x-type fragment ions, NETD generated intense neutral loss peaks corresponding to the entire or partial side-chain cleavage from amino acids constituting a given peptide. Thus, a critical step towards the characterization of this recently introduced fragmentation technique is a systematic study of synthetic peptides to identify common neutral losses and preferential fragmentation pathways. Examining 46 synthetic peptides with high mass accuracy and high resolution analysis permitted facile determination of the chemical composition of each neutral loss. We identified 19 unique neutral losses from 14 amino acids and three modified amino acids, and assessed the specificity and sensitivity of each neutral loss using a database of 1542 confidently identified peptides generated from NETD shotgun experiments employing high-pH separations and negative electrospray ionization. As residue-specific neutral losses indicate the presence of certain amino acids, we determined that many neutral losses have potential diagnostic utility. We envision this catalogue of neutral losses being incorporated into database search algorithms to improve peptide identification specificity and to further advance characterization of the acidic proteome. PMID:22290482

  1. Formation of radical cations of diaryloxadiazoles

    International Nuclear Information System (INIS)

    Helmstreit, W.

    1988-01-01

    The nature of the formation of the radical cation of the 2,5-bis-(p-diethylaminophenyl)-1,3,4-oxadiazole (PC) in liquid n-butyl chloride and acetonitrile has been investigated by observing excited state fluorescence and transient absorption using nanosecond pulse radiolysis and laser flash photolysis. The formation of solute oxonium ions has also been observed. At concentrations -4 mol dm -3 the growth time at which the transient absorption of the radical cation reaches the maximum follows the rise time of the electron pulse ( 2 laser yields the solute radical cation in an acetonitrile solution of 2 x 10 -4 mol dm -3 PC via an electronically excited state. Here, the generation time was smaller than 5 ns. The yield of the cation is increased by addition of CCl 4 . A reaction mechanism is proposed that explains the fast cation formation in terms of an exciplex formed by interaction between an electronically excited state of diaryloxadiazole and the ground state of the solvent. This exciplex yields the solute radical cation. (author)

  2. Luminescent sulfides of monovalent and trivalent cations

    International Nuclear Information System (INIS)

    1975-01-01

    The invention discloses a family of luminescent materials or phosphors having a rhombohedral crystal structure and consisting essentially of a mixed host sulfide of at least one monovalent host cation and at least one trivalent host cation, and containing, for each mole of phosphor, 0.0005 to 0.05 mole of at least one activating cation. The monovalent host cations may be Na, K or Rb and Cs. The trivalent host cations may be Gd, La, Lu, Sc and Y. The activating cations may be one or more of trivalent As, Bi, Ce, Dy, Er, Pr, Sb, Sm, Tb and Tm; divalent Lu, Mn, Pb and Sn; and monovalent Ag, Cu and Tl. The novel phosphors may be used in devices to convert electron-beam, ultraviolet or x-ray energy to light in the visible spectrum. Such energy conversion can be employed for example in fluoroscopic screens, and in viewing screens of cathode-ray tubes and other electron tubes

  3. Divalent cation shrinks DNA but inhibits its compaction with trivalent cation.

    Science.gov (United States)

    Tongu, Chika; Kenmotsu, Takahiro; Yoshikawa, Yuko; Zinchenko, Anatoly; Chen, Ning; Yoshikawa, Kenichi

    2016-05-28

    Our observation reveals the effects of divalent and trivalent cations on the higher-order structure of giant DNA (T4 DNA 166 kbp) by fluorescence microscopy. It was found that divalent cations, Mg(2+) and Ca(2+), inhibit DNA compaction induced by a trivalent cation, spermidine (SPD(3+)). On the other hand, in the absence of SPD(3+), divalent cations cause the shrinkage of DNA. As the control experiment, we have confirmed the minimum effect of monovalent cation, Na(+) on the DNA higher-order structure. We interpret the competition between 2+ and 3+ cations in terms of the change in the translational entropy of the counterions. For the compaction with SPD(3+), we consider the increase in translational entropy due to the ion-exchange of the intrinsic monovalent cations condensing on a highly charged polyelectrolyte, double-stranded DNA, by the 3+ cations. In contrast, the presence of 2+ cation decreases the gain of entropy contribution by the ion-exchange between monovalent and 3+ ions.

  4. Neutrality Versus Materiality: A Thermodynamic Theory of Neutral Surfaces

    Directory of Open Access Journals (Sweden)

    Rémi Tailleux

    2016-09-01

    Full Text Available In this paper, a theory for constructing quasi-neutral density variables γ directly in thermodynamic space is formulated, which is based on minimising the absolute value of a purely thermodynamic quantity J n . Physically, J n has a dual dynamic/thermodynamic interpretation as the quantity controlling the energy cost of adiabatic and isohaline parcel exchanges on material surfaces, as well as the dependence of in-situ density on spiciness, in a description of water masses based on γ, spiciness and pressure. Mathematically, minimising | J n | in thermodynamic space is showed to be equivalent to maximising neutrality in physical space. The physics of epineutral dispersion is also reviewed and discussed. It is argued, in particular, that epineutral dispersion is best understood as the aggregate effect of many individual non-neutral stirring events (being understood here as adiabatic and isohaline events with non-zero buoyancy, so that it is only the net displacement aggregated over many events that is approximately neutral. This new view resolves an apparent paradox between the focus in neutral density theory on zero-buoyancy motions and the overwhelming evidence that lateral dispersion in the ocean is primarily caused by non-zero buoyancy processes such as tides, residual currents and sheared internal waves. The efficiency by which a physical process contributes to lateral dispersion can be characterised by its energy signature, with those processes releasing available potential energy (negative energy cost being more efficient than purely neutral processes with zero energy cost. The latter mechanism occurs in the wedge of instability, and its source of energy is the coupling between baroclinicity, thermobaricity, and density compensated temperature/salinity anomalies. Such a mechanism, which can only exist in a salty ocean, is speculated to be important for dissipating spiciness anomalies and neutral helicity. The paper also discusses potential

  5. Net Neutrality: Background and Issues

    National Research Council Canada - National Science Library

    Gilroy, Angele A

    2006-01-01

    .... The move to place restrictions on the owners of the networks that compose and provide access to the Internet, to ensure equal access and nondiscriminatory treatment, is referred to as "net neutrality...

  6. Weak neutral-current interactions

    International Nuclear Information System (INIS)

    Barnett, R.M.

    1978-08-01

    The roles of each type of experiment in establishing uniquely the values of the the neutral-current couplings of u and d quarks are analyzed together with their implications for gauge models of the weak and electromagnetic interactions. An analysis of the neutral-current couplings of electrons and of the data based on the assumption that only one Z 0 boson exists is given. Also a model-independent analysis of parity violation experiments is discussed. 85 references

  7. Accelerators for forming cationic technetium complexes useful as radiodiagnostic images

    International Nuclear Information System (INIS)

    Tweedle, M.F.

    1985-01-01

    This invention relates to compositions for making cationic radiodiagnostic agents and, in particular, to accelerator compounds for labelling such cationic radiodiagnostic agents, kits for preparing such 99m Tc-labelled cationic radiodiagnostic agents with technetium, and methods for labelling such cationic radiodiagnostic agents with technetium

  8. A Cation-containing Polymer Anion Exchange Membrane based on Poly(norbornene)

    Science.gov (United States)

    Beyer, Frederick; Price, Samuel; Ren, Xiaoming; Savage, Alice

    Cation-containing polymers are being studied widely for use as anion exchange membranes (AEMs) in alkaline fuel cells (AFCs) because AEMs offer a number of potential benefits including allowing a solid state device and elimination of the carbonate poisoning problem. The successful AEM will combine high performance from several orthogonal properties, having robust mechanical strength even when wet, high hydroxide conductivity, and the high chemical stability required for long device lifetimes. In this study, we have synthesized a model cationic polymer that combines three of the key advantages of Nafion. The polymer backbone based on semicrystalline atactic poly(norbornene) offers good mechanical properties. A flexible, ether-based tether between the backbone and fixed cation charged species (quaternary ammonium) should provide the low-Tg, hydrophilic environment required to facilitate OH- transport. Finally, methyl groups have been added at the beta position relative to the quaternary ammonium cation to prevent Hoffman elimination, one mechanism by which AEMs are neutralized in a high pH environment. In this poster, we will present our findings on mechanical properties, morphology, charge transport, and chemical stability of this material.

  9. Gas phase chemistry of N-benzylbenzamides with silver(I) cations: characterization of benzylsilver cation.

    Science.gov (United States)

    Sun, Hezhi; Jin, Zhe; Quan, Hong; Sun, Cuirong; Pan, Yuanjiang

    2015-03-07

    The benzylsilver cation which emerges from the collisional dissociation of silver(I)-N-benzylbenzamide complexes was characterized by deuterium-labeling experiments, theoretical calculations, breakdown curves and substituent effects. The nucleophilic attack of the carbonyl oxygen on an α-hydrogen results in the generation of the benzylsilver cation, which is competitive to the AgH loss with the α-hydrogen.

  10. Effect of Divalent Cations on RED Performance and Cation Exchange Membrane Selection to Enhance Power Densities.

    Science.gov (United States)

    Rijnaarts, Timon; Huerta, Elisa; van Baak, Willem; Nijmeijer, Kitty

    2017-11-07

    Reverse electrodialysis (RED) is a membrane-based renewable energy technology that can harvest energy from salinity gradients. The anticipated feed streams are natural river and seawater, both of which contain not only monovalent ions but also divalent ions. However, RED using feed streams containing divalent ions experiences lower power densities because of both uphill transport and increased membrane resistance. In this study, we investigate the effects of divalent cations (Mg 2+ and Ca 2+ ) on RED and demonstrate the mitigation of those effects using both novel and existing commercial cation exchange membranes (CEMs). Monovalent-selective Neosepta CMS is known to block divalent cations transport and can therefore mitigate reductions in stack voltage. The new multivalent-permeable Fuji T1 is able to transport divalent cations without a major increase in resistance. Both strategies significantly improve power densities compared to standard-grade CEMs when performing RED using streams containing divalent cations.

  11. Synthesis and butadiene polymerization behaviors of cationic cobalt-based catalyst

    Directory of Open Access Journals (Sweden)

    Li Liu

    2017-01-01

    Full Text Available A series of cationic cobalt-based compounds bearing different neutral N-bearing ligands (1,10-phenanthroline, bipyridine, benzimidazole, terpyridine and anionic ligands (trifluoromethanesulfonate, methanesulfonate were synthesized and the simple compound, Co(Phen2Cl2, was also prepared as a reference compound. All the compounds were characterized along with infrared spectra analysis and some of them were further confirmed by single crystal X-ray crystallographic analysis. Upon activation with ethylaluminum sesquichloride, these cationic cobalt(II compounds showed high catalytic activities for butadiene polymerization. The detailed investigations were carried out to disclose the influence of various polymerization conditions, sterical and electronic parameters of the ligands on their performing activities of the compounds.

  12. Ordered microporous layered lanthanide 1,3,5-benzenetriphosphonates pillared with cationic organic molecules.

    Science.gov (United States)

    Araki, Takahiro; Kondo, Atsushi; Maeda, Kazuyuki

    2015-04-13

    Novel isomorphous pillared-layer-type crystalline lanthanide 1,3,5-benzenetriphosphonates were prepared with bpy and dbo as organic pillars (LnBP-bpy and LnBP-dbo; Ln: Ce, Pr, and Nd). Ab initio crystal structure solution using synchrotron X-ray powder diffraction data revealed that the organic pillars do not exist as neutral coordinating ligands but as cationic molecules. Especially the LnBP-dbo phases have ordered interlayer space filled with water molecules between the dbo pillars, and the interlayer water is successfully removed by heating under vacuum with slightly distorted but basically retained pillared layer structures. Microporosity of the materials is confirmed by adsorption of nitrogen, carbon dioxide, and hydrogen gases. Such microporous layered metal phosphonates pillared with cationic molecules should be unprecedented and should offer new strategies to design ordered microporous materials. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Experimental and theoretical study of 2,6-difluorophenylnitrene, its radical cation, and their rearrangement products in argon matrices.

    Science.gov (United States)

    Carra, Claudio; Nussbaum, Rafael; Bally, Thomas

    2006-06-12

    2,6-Difluorophenylnitrene was reinvestigated both experimentally, in Ar matrices at 10 K, and computationally, by DFT and CASSCF/CASPT2 calculations. Almost-pure samples of both neutral rearrangement products (the bicyclic azirine and the cyclic ketenimine) of a phenylnitrene were prepared and characterized for the first time. These samples were then subjected to X-irradiation in the presence of CH2Cl2 as an electron scavenger, which led to ionization of the neutral intermediates. Thereby, it was shown that only the phenylnitrene and the cyclic ketenimine yield stable radical cations, whereas the bicyclic azirine decays to both of these compounds on ionization. The cyclic ketenimine yields a novel aromatic azatropylium-type radical cation. The electronic structure of the title compound is discussed in detail, and its relation to those of the iso-pi-electronic benzyl radical and phenylcarbene is traced.

  14. Gas cell neutralizers (Fundamental principles)

    International Nuclear Information System (INIS)

    Fuehrer, B.

    1985-06-01

    Neutralizing an ion-beam of the size and energy levels involved in the neutral-particle-beam program represents a considerable extension of the state-of-the-art of neutralizer technology. Many different mediums (e.g., solid, liquid, gas, plasma, photons) can be used to strip the hydrogen ion of its extra electron. A large, multidisciplinary R and D effort will no doubt be required to sort out all of the ''pros and cons'' of these various techniques. The purpose of this particular presentation is to discuss some basic configurations and fundamental principles of the gas type of neutralizer cell. Particular emphasis is placed on the ''Gasdynamic Free-Jet'' neutralizer since this configuration has the potential of being much shorter than other type of gas cells (in the beam direction) and it could operate in nearly a continuous mode (CW) if necessary. These were important considerations in the ATSU design which is discussed in some detail in the second presentation entitled ''ATSU Point Design''

  15. Electromagnetic trapping of neutral atoms

    International Nuclear Information System (INIS)

    Metcalf, H.J.

    1986-01-01

    Cooling and trapping of neutral atoms is a new branch of applied physics that has potential for application in many areas. The authors present an introduction to laser cooling and magnetic trapping. Some basic ideas and fundamental limitations are discussed, and the first successful experiments are reviewed. Trapping a neutral object depends on the interaction between an inhomogeneous electromagnetic field and a multiple moment that results in the exchange of kinetic for potential energy. In neutral atom traps, the potential energy must be stored as internal atomic energy, resulting in two immediate and extremely important consequences. First, the atomic energy levels will necessarily shift as the atoms move in the trap, and, second, practical traps for ground state neutral atoms atr necessarily very shallow compared to thermal energy. This small depth also dictates stringent vacuum requirements because a trapped atom cannot survive a single collision with a thermal energy background gas molecule. Neutral trapping, therefore, depends on substantial cooling of a thermal atomic sample and is inextricably connected with the cooling process

  16. Forging Colloidal Nanostructures via Cation Exchange Reactions.

    Science.gov (United States)

    De Trizio, Luca; Manna, Liberato

    2016-09-28

    Among the various postsynthesis treatments of colloidal nanocrystals that have been developed to date, transformations by cation exchange have recently emerged as an extremely versatile tool that has given access to a wide variety of materials and nanostructures. One notable example in this direction is represented by partial cation exchange, by which preformed nanocrystals can be either transformed to alloy nanocrystals or to various types of nanoheterostructures possessing core/shell, segmented, or striped architectures. In this review, we provide an up to date overview of the complex colloidal nanostructures that could be prepared so far by cation exchange. At the same time, the review gives an account of the fundamental thermodynamic and kinetic parameters governing these types of reactions, as they are currently understood, and outlines the main open issues and possible future developments in the field.

  17. Forging Colloidal Nanostructures via Cation Exchange Reactions

    Science.gov (United States)

    2016-01-01

    Among the various postsynthesis treatments of colloidal nanocrystals that have been developed to date, transformations by cation exchange have recently emerged as an extremely versatile tool that has given access to a wide variety of materials and nanostructures. One notable example in this direction is represented by partial cation exchange, by which preformed nanocrystals can be either transformed to alloy nanocrystals or to various types of nanoheterostructures possessing core/shell, segmented, or striped architectures. In this review, we provide an up to date overview of the complex colloidal nanostructures that could be prepared so far by cation exchange. At the same time, the review gives an account of the fundamental thermodynamic and kinetic parameters governing these types of reactions, as they are currently understood, and outlines the main open issues and possible future developments in the field. PMID:26891471

  18. Magnetic Resonance Studies of Proton Loss from Carotenoid Radical Cations

    Energy Technology Data Exchange (ETDEWEB)

    Kispert, Lowell D [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Focsan, A Ligia [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Konovalova, Tatyana A [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Lawrence, Jesse [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Bowman, Michael K [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Dixon, David A [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Molnar, Peter [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Deli, Jozsef [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2007-06-11

    Carotenoids, intrinsic components of reaction centers and pigment-protein complexes in photosynthetic membranes, play a photoprotective role and serve as a secondary electron donor. Before optimum use of carotenoids can be made in artificial photosynthetic systems, their robust nature in living materials requires extensive characterization of their electron transfer, radical trapping ability, stability, structure in and on various hosts, and photochemical behavior. Pulsed ENDOR and 2D-HYSCORE studies combined with DFT calculations reveal that photo-oxidation of natural zeaxanthin (I) and violaxanthin (II) on silica-alumina produces not only the carotenoid radical cations (Car•+) but also neutral radicals (#Car•) by proton loss from the methyl groups at positions 5 or 5', and possibly 9 or 9' and 13 or 13'. Notably, the proton loss favored in I at the 5 position by DFT calculations, is unfavorable in II due to the epoxide at the 5, 6 position. DFT calculations predict the isotropic methyl proton couplings of 8-10 MHz for Car•+ which agree with the ENDOR for carotenoid α-conjugated radical cations. Large α-proton hyperfine coupling constants (>10 MHz) determined from HYSCORE are assigned from the DFT calculations to neutral carotenoid radicals. Proton loss upon photolysis was also examined as a function of carotenoid polarity [Lycopene (III) versus 8'-apo-β-caroten-8'-al (IV)]; hydrogen bonding [Lutein (V) versus III]; host [silica-alumina versus MCM-41 molecular sieve]; and substituted metal in MCM-41. Loss of H+ from the 5(5'), 9(9') or 13(13') methyl positions has importance in photoprotection. Photoprotection involves nonphotochemical quenching (NPQ) in which 1Ch1* decays via energy transfer to the carotenoid which returns to the ground state by thermal dissipation; or via electron transfer to form a charge transfer state (I •+…Chl•-), lower in energy than 1Chl*. Formation of I •+ results in bond

  19. Magnetic Resonance Studies of Proton Loss from Carotenoid Radical Cations

    International Nuclear Information System (INIS)

    Kispert, Lowell D.; Focsan, A. Ligia; Konovalova, Tatyana A.; Lawrence, Jesse; Bowman, Michael K.; Dixon, David A.; Molnar, Peter; Deli, Jozsef

    2007-01-01

    Carotenoids, intrinsic components of reaction centers and pigment-protein complexes in photosynthetic membranes, play a photoprotective role and serve as a secondary electron donor. Before optimum use of carotenoids can be made in artificial photosynthetic systems, their robust nature in living materials requires extensive characterization of their electron transfer, radical trapping ability, stability, structure in and on various hosts, and photochemical behavior. Pulsed ENDOR and 2D-HYSCORE studies combined with DFT calculations reveal that photo-oxidation of natural zeaxanthin (I) and violaxanthin (II) on silica-alumina produces not only the carotenoid radical cations (Car ·+ ) but also neutral radicals ((number s ign)Car · ) by proton loss from the methyl groups at positions 5 or 5(prime), and possibly 9 or 9(prime) and 13 or 13(prime). Notably, the proton loss favored in I at the 5 position by DFT calculations, is unfavorable in II due to the epoxide at the 5, 6 position. DFT calculations predict the isotropic methyl proton couplings of 8-10 MHz for Car # center d ot# + which agree with the ENDOR for carotenoid π-conjugated radical cations. Large α-proton hyperfine coupling constants (>10 MHz) determined from HYSCORE are assigned from the DFT calculations to neutral carotenoid radicals. Proton loss upon photolysis was also examined as a function of carotenoid polarity (Lycopene (III) versus 8(prime)-apo-β-caroten-8(prime)-al (IV)); hydrogen bonding (Lutein (V) versus III); host (silica-alumina versus MCM-41 molecular sieve); and substituted metal in MCM-41. Loss of H + from the 5(5(prime)), 9(9(prime)) or 13(13(prime)) methyl positions has importance in photoprotection. Photoprotection involves nonphotochemical quenching (NPQ) in which 1 Ch1* decays via energy transfer to the carotenoid which returns to the ground state by thermal dissipation; or via electron transfer to form a charge transfer state (I # center d ot# + ...Chl # center d ot# - ), lower in

  20. Effect of alkaline earth metal and magnesium cations on cadmium extraction from chloride solutions by tributyl phosphate

    International Nuclear Information System (INIS)

    Prokuev, V.A.; Belousov, E.A.

    1985-01-01

    At 298 K thermodynamic constants of cadmium (2) extraction from chloride solutions of magnesium, calcium, strontium and barium by tributyl phosphate are calculated. It is established, that logarithm of the thermodynamic extraction constant is in a linear dependence from the change in the cation hydration enthalpy in agqueous solution. It is shown, that activity coefficient of neutral complex CdVCl 2 differs from one, and it is the higher the more stable the complex is in alkaline earth metal chloride solutions

  1. Measurement of plasma production and neutralization in gas neutralizers

    International Nuclear Information System (INIS)

    Maor, D.; Meron, M.; Johnson, B.; Jones, K.; Agagu, A.; Hu, B.

    1986-01-01

    In order to satisfy the need of experimental data for the designing of gas neutralizers we have started a project aimed at measuring all relevant cross sections for the charge exchange of H - , H 0 and H + projectiles, as well as the cross sections for the production of ions in the target. The expected results of these latter measurements are shown schematically

  2. Neutral currents in semileptonic reactions

    International Nuclear Information System (INIS)

    Paschos, E.A.

    1975-05-01

    The evidence for weak neutral currents is analyzed in semileptonic reactions with special emphasis on their Lorentz and internal symmetry structure. It is found that present observations are consistent with the expectations of gauge theories, but other possibilities can not be ruled out. Of particular interest in this respect is the presence of a large isoscalar component. The excitation of the Δ-resonance by neutral currents is analyzed, and pion-nucleon mass distributions are presented. Charge asymmetries sensitive to isoscalar-isovector interferences are discussed. (U.S.)

  3. Overcoming the inhibitory effect of serum on lipofection by increasing the charge ratio of cationic liposome to DNA.

    Science.gov (United States)

    Yang, J P; Huang, L

    1997-09-01

    Since cationic liposome was first developed as a lipofection reagent, a drawback has been noted in that the efficiency of lipofection decreases dramatically after addition of serum to the lipofection medium. This drawback hampers the application of cationic liposome for systematic delivery of genes. In the present studies, we found that the effect of serum on DC-chol liposome-mediated lipofection is dependent on the charge ratio of liposome to DNA. Serum inhibited lipofection activity of the lipoplex at low charge ratios, whereas it enhanced the lipofection activity at high charge ratios. This phenomenon was observed using DOTAP/DOPE but not lipofectamine. Measurement of cellular association of DNA showed that serum could reduce the binding of lipoplex to cells at all tested charge ratios, i.e. 0-10.6. Removal of negatively charged proteins from serum by DEAE Sephacel column abolished the inhibitory effect of serum on lipofection. The fraction contained only negatively charged serum proteins which strongly inhibited lipofection at low charge ratios but not at higher charge ratios. Furthermore, preincubation of serum with positively charged polylysine, which neutralized negatively charged serum proteins, eliminated the inhibitory effect of serum on lipofection. In summary, inactivation of cationic liposome by serum is due to negatively charged serum proteins and it can be overcome by increasing charge ratio of cationic liposome-DNA lipoplexes or by neutralizing the serum with polylysine.

  4. Amphiphilic cationic peptides mediate cell adhesion to plastic surfaces.

    Science.gov (United States)

    Rideout, D C; Lambert, M; Kendall, D A; Moe, G R; Osterman, D G; Tao, H P; Weinstein, I B; Kaiser, E T

    1985-09-01

    Four amphiphilic peptides, each with net charges of +2 or more at neutrality and molecular weights under 4 kilodaltons, were found to mediate the adhesion of normal rat kidney fibroblasts to polystyrene surfaces. Two of these peptides, a model for calcitonin (peptide 1, MCT) and melittin (peptide 2, MEL), form amphiphilic alpha-helical structures at aqueous/nonpolar interfaces. The other two, a luteinizing hormone-releasing hormone model (peptide 3, LHM) and a platelet factor model (peptide 4, MPF) form beta-strand structures in amphiphilic environments. Although it contains only 10 residues, LHM mediated adhesion to surfaces coated with solutions containing as little as 10 pmoles/ml of peptide. All four of these peptides were capable of forming monolayers at air-buffer interfaces with collapse pressures greater than 20 dynes/cm. None of these four peptides contains the tetrapeptide sequence Arg-Gly-Asp-Ser, which has been associated with fibronectin-mediated cell adhesion. Ten polypeptides that also lacked the sequence Arg-Gly-Asp-Ser but were nonamphiphilic and/or had net charges less than +2 at neutrality were all incapable of mediating cell adhesion (Pierschbacher and Ruoslahti, 1984). The morphologies of NRK cells spread on polystyrene coated with peptide LHM resemble the morphologies on fibronectin-coated surfaces, whereas cells spread on surfaces coated with MCT or MEL exhibit strikingly different morphologies. The adhesiveness of MCT, MEL, LHM, and MPF implies that many amphiphilic cationic peptides could prove useful as well defined adhesive substrata for cell culture and for studies of the mechanism of cell adhesion.

  5. Restructuring of a peat in interaction with multivalent cations: effect of cation type and aging time.

    Directory of Open Access Journals (Sweden)

    Yamuna Kunhi Mouvenchery

    Full Text Available It is assumed to be common knowledge that multivalent cations cross-link soil organic matter (SOM molecules via cation bridges (CaB. The concept has not been explicitly demonstrated in solid SOM by targeted experiments, yet. Therefore, the requirements for and characteristics of CaB remain unidentified. In this study, a combined experimental and molecular modeling approach was adopted to investigate the interaction of cations on a peat OM from physicochemical perspective. Before treatment with salt solutions of Al(3+, Ca(2+ or Na(+, respectively, the original exchangeable cations were removed using cation exchange resin. Cation treatment was conducted at two different values of pH prior to adjusting pH to 4.1. Cation sorption is slower (>>2 h than deprotonation of functional groups (<2 h and was described by a Langmuir model. The maximum uptake increased with pH of cation addition and decreased with increasing cation valency. Sorption coefficients were similar for all cations and at both pH. This contradicts the general expectations for electrostatic interactions, suggesting that not only the interaction chemistry but also spatial distribution of functional groups in OM determines binding of cations in this peat. The reaction of contact angle, matrix rigidity due to water molecule bridges (WaMB and molecular mobility of water (NMR analysis suggested that cross-linking via CaB has low relevance in this peat. This unexpected finding is probably due to the low cation exchange capacity, resulting in low abundance of charged functionalities. Molecular modeling demonstrates that large average distances between functionalities (∼3 nm in this peat cannot be bridged by CaB-WaMB associations. However, aging strongly increased matrix rigidity, suggesting successive increase of WaMB size to connect functionalities and thus increasing degree of cross-linking by CaB-WaMB associations. Results thus demonstrated that the physicochemical structure of OM is

  6. Adsorption of cationic amylopectin on microcrystalline cellulose.

    NARCIS (Netherlands)

    Steeg, van de H.G.M.; Keizer, de A.; Cohen Stuart, M.A.; Bijsterbosch, B.H.

    1993-01-01

    The effects of electrolyte concentration and pH on the adsorption of cationic amylopectin on microcrystalline cellulose were investigated. The adsorbed amount in the pseudo-plateau of the isotherm showed a maximum as a function of the electrolyte concentration. We compared the data with a recent

  7. Alkynylcarbenium ions and related unsaturated cations

    Energy Technology Data Exchange (ETDEWEB)

    Lukyanov, Sergey M; Koblik, Alla V; Muradyan, Lyudmila A [Institute of Physical and Organic Chemistry, Rostov State University, Rostov-on-Don (Russian Federation)

    1998-10-31

    Published data on carbenium ions containing carbon-carbon triple bonds both directly conjugated with the carbenium centre and separated from it are surveyed and described systematically. Ammonium, diazonium, iminium, phosphonium and iodonium cations containing alkynyl groups, which can be regarded as heteroanalogues of alkynylcarbenium ions, are also considered. The bibliography includes 283 references.

  8. Alkynylcarbenium ions and related unsaturated cations

    International Nuclear Information System (INIS)

    Lukyanov, Sergey M; Koblik, Alla V; Muradyan, Lyudmila A

    1998-01-01

    Published data on carbenium ions containing carbon-carbon triple bonds both directly conjugated with the carbenium centre and separated from it are surveyed and described systematically. Ammonium, diazonium, iminium, phosphonium and iodonium cations containing alkynyl groups, which can be regarded as heteroanalogues of alkynylcarbenium ions, are also considered. The bibliography includes 283 references

  9. Effect of cations on the hydrated proton.

    Science.gov (United States)

    Ottosson, Niklas; Hunger, Johannes; Bakker, Huib J

    2014-09-17

    We report on a strong nonadditive effect of protons and other cations on the structural dynamics of liquid water, which is revealed using dielectric relaxation spectroscopy in the frequency range of 1-50 GHz. For pure acid solutions, protons are known to have a strong structuring effect on water, leading to a pronounced decrease of the dielectric response. We observe that this structuring is reduced when protons are cosolvated with salts. This reduction is exclusively observed for combinations of protons with other ions; for all studied solutions of cosolvated salts, the effect on the structural dynamics of water is observed to be purely additive, even up to high concentrations. We derive an empirical model that quantitatively describes the nonadditive effect of cosolvated protons and cations. We argue that the effect can be explained from the special character of the proton in water and that Coulomb fields exerted by other cations, in particular doubly charged cations like Mg(2+)aq and Ca(2+)aq, induce a localization of the H(+)aq hydration structures.

  10. Mixed cation effect in sodium aluminosilicate glasses

    DEFF Research Database (Denmark)

    Kjeldsen, Jonas; Smedskjær, Morten Mattrup; Mauro, John C.

    , network structure, and the resistances associated with the deformation processes in mixed cation glasses by partially substituting magnesium for calcium and calcium for lithium in sodium aluminosilicate glasses. We use Raman and 27Al NMR spectroscopies to obtain insights into the structural...

  11. Cationic flotation of some lithium ores

    International Nuclear Information System (INIS)

    Valadao, G.E.S.; Peres, A.E.C.; Silva, H.C. da

    1984-01-01

    The cationic flotation of some lithium ores (spodumene, amblygonite, petalite, lepidolite) is studied by the measure of zeta potential and micro-flotation tests in Hallimond tube. The effect of some modifier agents (corn starch, meta sodium silicate) on the lithium flotation is studied. (M.A.C.) [pt

  12. Al cation induces aggregation of serum proteins.

    Science.gov (United States)

    Chanphai, P; Kreplak, L; Tajmir-Riahi, H A

    2017-07-15

    Al cation is known to induce protein fibrillation and causes several neurodegenerative disorders. We report the spectroscopic, thermodynamic analysis and AFM imaging for the Al cation binding process with human serum albumin (HSA), bovine serum albumin (BSA) and milk beta-lactoglobulin (b-LG) in aqueous solution at physiological pH. Hydrophobicity played a major role in Al-protein interactions with more hydrophobic b-LG forming stronger Al-protein complexes. Thermodynamic parameters ΔS, ΔH and ΔG showed Al-protein bindings occur via hydrophobic and H-bonding contacts for b-LG, while van der Waals and H-bonding interactions prevail in HSA and BSA adducts. AFM clearly indicated that aluminum cations are able to force BSA and b-LG into larger or more robust aggregates than HSA, with HSA 4±0.2 (SE, n=801) proteins per aggregate, for BSA 17±2 (SE, n=148), and for b-LG 12±3 (SE, n=151). Thioflavin T test showed no major protein fibrillation in the presence of Al cation. Al complexation induced major alterations of protein conformations with the order of perturbations b-LG>BSA>HSA. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Chemical reactivity of cation-exchanged zeolites

    NARCIS (Netherlands)

    Pidko, E.A.

    2008-01-01

    Zeolites modified with metal cations have been extensively studied during the last two decades because of their wide application in different technologically important fields such as catalysis, adsorption and gas separation. Contrary to the well-understood mechanisms of chemical reactions catalyzed

  14. ITER Neutral Beam Injection System

    International Nuclear Information System (INIS)

    Ohara, Yoshihiro; Tanaka, Shigeru; Akiba, Masato

    1991-03-01

    A Japanese design proposal of the ITER Neutral Beam Injection System (NBS) which is consistent with the ITER common design requirements is described. The injection system is required to deliver a neutral deuterium beam of 75MW at 1.3MeV to the reactor plasma and utilized not only for plasma heating but also for current drive and current profile control. The injection system is composed of 9 modules, each of which is designed so as to inject a 1.3MeV, 10MW neutral beam. The most important point in the design is that the injection system is based on the utilization of a cesium-seeded volume negative ion source which can produce an intense negative ion beam with high current density at a low source operating pressure. The design value of the source is based on the experimental values achieved at JAERI. The utilization of the cesium-seeded volume source is essential to the design of an efficient and compact neutral beam injection system which satisfies the ITER common design requirements. The critical components to realize this design are the 1.3MeV, 17A electrostatic accelerator and the high voltage DC acceleration power supply, whose performances must be demonstrated prior to the construction of ITER NBI system. (author)

  15. Laser cooling of neutral atoms

    International Nuclear Information System (INIS)

    1993-01-01

    A qualitative description of laser cooling of neutral atoms is given. Two of the most important mechanisms utilized in laser cooling, the so-called Doppler Cooling and Sisyphus Cooling, are reviewed. The minimum temperature reached by the atoms is derived using simple arguments. (Author) 7 refs

  16. Climate Neutral Research Campuses | NREL

    Science.gov (United States)

    the background. Set an example for climate neutrality. Use NREL's climate action planning process and more. Climate Action Planning Process Identify the best technology options for a climate action plan . Climate Action Planning Tool Identify the best technology options for a climate action plan. Technology

  17. PLT neutral beam injection systems

    International Nuclear Information System (INIS)

    Menon, M.M.; Barber, G.C.; Blue, C.W.

    1979-01-01

    A brief description of the Princeton Large Torus (PLT) neutral beam injection system is given and its performance characteristics are outlined. A detailed operational procedure is included, as are some tips on troubleshooting. Proper operation of the source is shown to be a crucial factor in system performance

  18. Neutral Models with Generalised Speciation

    NARCIS (Netherlands)

    Haegeman, Bart; Etienne, Rampal S.

    Hubbell's neutral theory claims that ecological patterns such as species abundance distributions can be explained by a stochastic model based on simple assumptions. One of these assumptions, the point mutation assumption, states that every individual has the same probability to speciate. Etienne et

  19. Multimegawatt neutral beams for tokamaks

    International Nuclear Information System (INIS)

    Kunkel, W.B.

    1979-03-01

    Most of the large magnetic confinement experiments today and in the near future use high-power neutral-beam injectors to heat the plasma. This review briefly describes this remarkable technique and summarizes recent results as well as near term expectations. Progress has been so encouraging that it seems probable that tokamaks will achieve scientific breakeven before 1990

  20. Heavy neutral leptons at FASER

    Science.gov (United States)

    Kling, Felix; Trojanowski, Sebastian

    2018-05-01

    We study the prospects for discovering heavy neutral leptons at Forward Search Experiment (FASER), the newly proposed detector at the LHC. Previous studies showed that a relatively small detector with ˜10 m length and ≲1 m2 cross sectional area can probe large unconstrained parts of parameter space for dark photons and dark Higgs bosons. In this work, we show that FASER will also be sensitive to heavy neutral leptons that have mixing angles with the active neutrinos that are up to an order of magnitude lower than current bounds. In particular, this is true for heavy neutral leptons produced dominantly in B -meson decays, in which case FASER's discovery potential is comparable to the proposed SHiP detector. We also illustrate how the search for heavy neutral leptons at FASER will be complementary to ongoing searches in high-pT experiments at the LHC and can shed light on the nature of dark matter and the process of baryogenesis in the early Universe.

  1. Money neutrality: Rethinking the myth

    Directory of Open Access Journals (Sweden)

    Issaoui Fakhri

    2015-01-01

    Full Text Available Considered as an axiomatic basis of classical, neoclassical, and monetarist theories, the long-run money neutrality assumption does not always seem to be verified. Indeed, in our view, the money, in the sense of M2, can constitute a long-run channel of growth transmission. Thus, this paper examines the long-term relationship among money supply (M2, income (GDP, and prices (CPI. The subprime crisis in 2007 has shown that the demand for money does not only meet motives of transaction, precaution, and speculation but also of fictional or quasi-fictional future demands due to the fact that they are created without real counterparts. The capacity of production systems in developed countries to respond to increases in money supply by creating more wealth, involves the assumption of money neutrality in the long-run. However, in developing countries, the excess of money supply may lead to inflation trends. The present study has confirmed the long-term non-neutrality of money supply in the USA, and its neutrality in Gabon and Morocco.

  2. The manipulation of neutral particles

    International Nuclear Information System (INIS)

    Chu, S.

    1998-01-01

    The article is a translation of the lecture delivered on the occasion of the 1997 Nobel Prize awarding ceremony. The author's personal contribution to the discovery of laser cooling and trapping of neutral atoms is described, and applications of this phenomenon in atomic physics are highlighted. The article is completed by Mr. Steven Chu's autobiography

  3. Net Neutrality in the Netherlands

    NARCIS (Netherlands)

    van Eijk, N.

    2014-01-01

    The Netherlands is among the first countries that have put specific net neutrality standards in place. The decision to implement specific regulation was influenced by at least three factors. The first was the prevailing social and academic debate, partly due to developments in the United States. The

  4. Selective crystallization of cations with crown ethers

    International Nuclear Information System (INIS)

    Heffels, Dennis Egidius

    2014-01-01

    The aim of this work was to study the selectivity and preferences of the incorporation of differently sized cations in the cavities of various crown ethers and the characterization of the resulting compounds. The coordination preferences of crown ethers with different cavities have long been known, and the impact of other effects on the structure formation have increasingly become the focus of attention. In this work a comparative overview of the coordination preferences depending on various factors was undertaken. The focus was mainly on the variation of the cavity of the crown ether in the presence of differently sized cations. In addition, the effects of the solvent and differently coordinating anions have been investigated. Within the framework of this work, basic coordination preferences could be detected with rare earth nitrates, which are affected particularly by the choice of the solvent. The formation of different types of structures could be controlled by varying the conditions such that the incorporation of the cation in the cavity of the crown ether was influenced and the formation of a particular type of structure can be influenced partly by the choice of solvent. In this case no direct preferences for the incorporation into the cavity of the crown ether in relation to the cation size were observed for rare earth cations. However, the coordination of the crown ether leads in each case - for lanthanides - to rather high coordination numbers. A total of five new rare earth complexes and two structural variants could be observed with crown ethers. In the study of the selectivity of the incorporation into the cavity, known structures were also reproduced and further structures were characterized but the crystal structures not entirely solved. With the use of monovalent cations such as potassium, lithium or silver a total of nine new compounds could be synthesized, while no clear preferences for the incorporation of certain cations were detected. The

  5. Increased localized delivery of piroxicam by cationic nanoparticles after intra-articular injection.

    Science.gov (United States)

    Kim, Sung Rae; Ho, Myoung Jin; Kim, Sang Hyun; Cho, Ha Ra; Kim, Han Sol; Choi, Yong Seok; Choi, Young Wook; Kang, Myung Joo

    2016-01-01

    Piroxicam (PRX), a potent nonsteroidal anti-inflammatory drug, is prescribed to relieve postoperative and/or chronic joint pain. However, its oral administration often results in serious gastrointestinal adverse effects including duodenal ulceration. Thus, a novel cationic nanoparticle (NP) was explored to minimize the systemic exposure and increase the retention time of PRX in the joint after intra-articular (IA) injection, by forming micrometer-sized electrostatic clusters with endogenous hyaluronic acid (HA) in the synovial cavity. PRX-loaded NPs consisting of poly(lactic- co -glycolic acid), Eudragit RL, and polyvinyl alcohol were constructed with the following characteristics: particle size of 220 nm, zeta potential of 11.5 mV in phosphate-buffered saline, and loading amount of 4.0% (w/w) of PRX. In optical and hyperspectral observations, the cationic NPs formed more than 50 μm-sized aggregates with HA, which was larger than the intercellular gaps between synoviocytes. In an in vivo pharmacokinetic study in rats, area under the plasma concentration-time curve (AUC 0-24 h ) and maximum plasma concentration ( C max ) of PRX after IA injection of the cationic NPs were <70% ( P <0.05) and 60% ( P <0.05), respectively, compared to those obtained from drug solution. Moreover, the drug concentration in joint tissue 24 h after dosing with the cationic NPs was 3.2-fold ( P <0.05) and 1.8-fold ( P <0.05) higher than that from drug solution and neutrally charged NPs, respectively. Therefore, we recommend the IA cationic NP therapy as an effective alternative to traditional oral therapy with PRX, as it increases drug retention selectively in the joint.

  6. [Noncovalent cation-π interactions--their role in nature].

    Science.gov (United States)

    Fink, Krzysztof; Boratyński, Janusz

    2014-11-07

    Non-covalent interactions play an extremely important role in organisms. The main non-covalent interactions in nature are: ion-ion interactions, dipole-dipole interactions, hydrogen bonds, and van der Waals interactions. A new kind of intermolecular interactions--cation-π interactions--is gaining increasing attention. These interactions occur between a cation and a π system. The main contributors to cation-π interactions are electrostatic, polarization and, to a lesser extent, dispersion interactions. At first, cation-π interactions were studied in a gas phase, with metal cation-aromatic system complexes. The characteristics of these complexes are as follows: an increase of cation atomic number leads to a decrease of interaction energy, and an increase of cation charge leads to an increase of interaction energy. Aromatic amino acids bind with metal cations mainly through interactions with their main chain. Nevertheless, cation-π interaction with a hydrophobic side chain significantly enhances binding energy. In water solutions most cations preferentially interact with water molecules rather than aromatic systems. Cation-π interactions occur in environments with lower accessibility to a polar solvent. Cation-π interactions can have a stabilizing role on the secondary, tertiary and quaternary structure of proteins. These interactions play an important role in substrate or ligand binding sites in many proteins, which should be taken into consideration when the screening of effective inhibitors for these proteins is carried out. Cation-π interactions are abundant and play an important role in many biological processes.

  7. Stability of anionic polymers in presence of multivalent cations

    International Nuclear Information System (INIS)

    Sabbagh, Imad

    1997-01-01

    This research thesis aimed at studying the stability of poly-electrolytes in saline environments, and the interactions between ions and poly-electrolytes of different charge densities. For this purpose, the author more particularly studied specific interactions between anionic poly-electrolytes and multivalent cations. After a recall of properties of neutral polymers and poly-electrolytes in solution, the author evokes interactions between poly-electrolytes and counter-ions, and briefly presents two models of stability of poly-electrolytes in saline solutions. The next part presents various experimental spectroscopic and electrochemical techniques and results of the characterization of the used products. Spectroscopic techniques allow ion-polymer interactions at the atomic scale to be studied, and electrochemical techniques allow the behaviour of small ions to be studied. The author then discusses the main differences of solubility between poly-electrolytes containing sulphonate or sulphate groups and those containing carboxylate groups. A model is then developed to generalise phase diagrams of a poly-electrolyte with respect to the chemical affinity of its functional group with ions of opposite sign. The author then addresses the behaviour of a non charged polyacrylic acid in various saline solutions, and presents a phase diagram model [fr

  8. Stability of anionic polymers in presence of multivalent cations

    International Nuclear Information System (INIS)

    Sabbagh, Imad

    1997-01-01

    The objectives of this research thesis were to study the stability of poly-electrolytes in saline environments, and the interactions between ions and poly-electrolytes of different charge densities. After a recall of the properties of neutral polymers and of poly-electrolytes in solution, the author evokes the interactions between poly-electrolytes and counter-ions, and briefly presents two models of stability of poly-electrolytes in saline solutions. Then, he presents different experimental techniques (scattering techniques and electrochemical techniques) and the results obtained when characterizing the used compounds. In the next part, the author discusses the basic differences of solubility between poly-electrolytes with sulfonate or sulfate groups and those with carboxylate groups. A simple model, inspired by the electrostatic model, allows poly-electrolyte phase diagram to be generalised with respect to the chemical affinity of its functional group with ions of opposed sign. The author then reports the study of the behaviour of non-charged poly-acrylic acid in various saline solutions, and then checks the behaviour of this acid within an intermediate range of dissociation level. The poly-acrylic acid structure and the distribution of ions before de-mixing are studied by X-ray and neutron scattering. The author finally tries to understand what is going on when multivalent cations are replaced by positively charged nano-metric particles (dendrimers) [fr

  9. Histidine, lysine, and arginine radical cations: isomer control via the choice of auxiliary ligand (L) in the dissociation of [CuII(L)amino acid]*2+ complexes.

    Science.gov (United States)

    Ke, Yuyong; Zhao, Junfang; Verkerk, Udo H; Hopkinson, Alan C; Siu, K W Michael

    2007-12-27

    Histidine, lysine, and arginine radical cations have been generated through collision-induced dissociation (CID) of complexes [CuII(auxiliary ligand)namino acid]*2+, using tri-, bi-, as well as monodentate auxiliary ligands. On the basis of the observed CID products, the existence of two isomeric amino-acid populations is postulated. The Type 1 radical cations of histidine and lysine, stable on the mass spectrometer time scale, were found to lose water, followed by the loss of carbon monoxide under more energetic CID conditions. The arginine Type 1 radical cation behaved differently, losing dehydroalanine. The Type 2 radical cations were metastable and easily fragmented by the loss of carbon dioxide, effectively preventing direct observation. Type 1 radical cations are proposed to result from neutral (canonical) amino-acid coordination, whereas Type 2 radical cations are from zwitterionic amino-acid coordination to copper in the complex. The ratio of Type 1/Type 2 ions was found to be dependent on the auxiliary ligand, providing a method of controlling which radical cation would be formed primarily. Density functional calculations at B3LYP/6-311++G(d,p) have been used to determine the relative energies of five His*+ isomers. Barriers against interconversion between the isomers and against fragmentation have been calculated, giving insight as to why the Type 1 ions are stable, while only fragmentation products of the Type 2 ions are observable under CID conditions.

  10. Structure relationship of cationic lipids on gene transfection mediated by cationic liposomes.

    Science.gov (United States)

    Paecharoenchai, Orapan; Niyomtham, Nattisa; Apirakaramwong, Auayporn; Ngawhirunpat, Tanasait; Rojanarata, Theerasak; Yingyongnarongkul, Boon-ek; Opanasopit, Praneet

    2012-12-01

    The aim of this study was to investigate the transfection efficiency of cationic liposomes formulated with phosphatidylcholine (PC) and novel synthesized diethanolamine-based cationic lipids at a molar ratio of 5:1 in comparison with Lipofectamine™ 2000. Factors affecting transfection efficiency and cell viability, including the chemical structure of the cationic lipids, such as different amine head group (diamine and polyamine; and non-spermine and spermine) and acyl chain lengths (C14, C16, and C18) and the weight ratio of liposomes to DNA were evaluated on a human cervical carcinoma cell line (HeLa cells) using the pDNA encoding green fluorescent protein (pEGFP-C2). Characterizations of these lipoplexes in terms of size and charge measurement and agarose gel electrophoresis were performed. The results from this study revealed that almost no transfection was observed in the liposome formulations composed of cationic lipids with a non-spermine head group. In addition, the transfection efficiency of these cationic liposomes was in the following order: spermine-C14 > spermine-C16 > spermine-C18. The highest transfection efficiency was observed in the formulation of spermine-C14 liposomes at a weight ratio of 25; furthermore, this formulation was safe for use in vitro. In conclusion, cationic liposomes containing spermine head groups demonstrated promising potential as gene carriers.

  11. Fluconazole affects the alkali-metal-cation homeostasis and susceptibility to cationic toxic compounds of Candida glabrata.

    Science.gov (United States)

    Elicharova, Hana; Sychrova, Hana

    2014-08-01

    Candida glabrata is a salt-tolerant and fluconazole (FLC)-resistant yeast species. Here, we analyse the contribution of plasma-membrane alkali-metal-cation exporters, a cation/proton antiporter and a cation ATPase to cation homeostasis and the maintenance of membrane potential (ΔΨ). Using a series of single and double mutants lacking CNH1 and/or ENA1 genes we show that the inability to export potassium and toxic alkali-metal cations leads to a slight hyperpolarization of the plasma membrane of C. glabrata cells; this hyperpolarization drives more cations into the cells and affects cation homeostasis. Surprisingly, a much higher hyperpolarization of C. glabrata plasma membrane was produced by incubating cells with subinhibitory concentrations of FLC. FLC treatment resulted in a substantially increased sensitivity of cells to various cationic drugs and toxic cations that are driven into the cell by negative-inside plasma-membrane potential. The effect of the combination of FLC plus cationic drug treatment was enhanced by the malfunction of alkali-metal-cation transporters that contribute to the regulation of membrane potential and cation homeostasis. In summary, we show that the combination of subinhibitory concentrations of FLC and cationic drugs strongly affects the growth of C. glabrata cells. © 2014 The Authors.

  12. Charging induced emission of neutral atoms from NaCl nanocube corners

    International Nuclear Information System (INIS)

    Ceresoli, Davide; Zykova-Timan, Tatyana; Tosatti, Erio

    2008-01-01

    Detachment of neutral cations/anions from solid alkali halides can in principle be provoked by donating/subtracting electrons to the surface of alkali halide crystals, but generally constitutes a very endothermic process. However, the amount of energy required for emission is smaller for atoms located in less favorable positions, such as surface steps and kinks. For a corner ion in an alkali halide cube the binding is the weakest, so it should be easier to remove that atom, once it is neutralized. We carried out first principles density functional calculations and simulations of neutral and charged NaCl nanocubes, to establish the energetics of extraction of neutralized corner ions. Following hole donation (electron removal) we find that detachment of neutral Cl corner atoms will require a limited energy of about 0.8 eV. Conversely, following the donation of an excess electron to the cube, a neutral Na atom is extractable from the corner at the lower cost of about 0.6 eV. Since the cube electron affinity level (close to that a NaCl(100) surface state, which we also determine) is estimated to lie about 1.8 eV below vacuum, the overall energy balance upon donation to the nanocube of a zero-energy electron from vacuum will be exothermic. The atomic and electronic structure of the NaCl(100) surface, and of the nanocube Na and Cl corner vacancies are obtained and analyzed as a byproduct

  13. (4 + 3) Cycloadditions of Nitrogen-Stabilized Oxyallyl Cations

    Science.gov (United States)

    Lohse, Andrew G.; Hsung, Richard P.

    2011-01-01

    The use of heteroatom-substituted oxyallyl cations in (4 + 3) cycloadditions has had a tremendous impact on the development of cycloaddition chemistry. Extensive efforts have been exerted toward investigating the effect of oxygen-, sulfur-, and halogen-substituents on the reactivity of oxyallyl cations. Most recently, the use of nitrogen-stabilized oxyallyl cations has gained prominence in the area of (4 + 3) cycloadditions. The following article will provide an overview of this concept utilizing nitrogen-stabilized oxyallyl cations. PMID:21384451

  14. Sulfation and cation effects on the conformational properties of the glycan backbone of chondroitin sulfate disaccharides.

    Science.gov (United States)

    Faller, Christina E; Guvench, Olgun

    2015-05-21

    Chondroitin sulfate (CS) is one of several glycosaminoglycans that are major components of proteoglycans. A linear polymer consisting of repeats of the disaccharide -4GlcAβ1-3GalNAcβ1-, CS undergoes differential sulfation resulting in five unique sulfation patterns. Because of the dimer repeat, the CS glycosidic "backbone" has two distinct sets of conformational degrees of freedom defined by pairs of dihedral angles: (ϕ1, ψ1) about the β1-3 glycosidic linkage and (ϕ2, ψ2) about the β1-4 glycosidic linkage. Differential sulfation and the possibility of cation binding, combined with the conformational flexibility and biological diversity of CS, complicate experimental efforts to understand CS three-dimensional structures at atomic resolution. Therefore, all-atom explicit-solvent molecular dynamics simulations with Adaptive Biasing Force sampling of the CS backbone were applied to obtain high-resolution, high-precision free energies of CS disaccharides as a function of all possible backbone geometries. All 10 disaccharides (β1-3 vs β1-4 linkage × five different sulfation patterns) were studied; additionally, ion effects were investigated by considering each disaccharide in the presence of either neutralizing sodium or calcium cations. GlcAβ1-3GalNAc disaccharides have a single, broad, thermodynamically important free-energy minimum, whereas GalNAcβ1-4GlcA disaccharides have two such minima. Calcium cations but not sodium cations bind to the disaccharides, and binding is primarily to the GlcA -COO(-) moiety as opposed to sulfate groups. This binding alters the glycan backbone thermodynamics in instances where a calcium cation bound to -COO(-) can act to bridge and stabilize an interaction with an adjacent sulfate group, whereas, in the absence of this cation, the proximity of a sulfate group to -COO(-) results in two like charges being both desolvated and placed adjacent to each other and is found to be destabilizing. In addition to providing information

  15. Neutral atom traps of radioactives

    International Nuclear Information System (INIS)

    Behr, J.A.

    2003-01-01

    Neutral atoms trapped with modern laser cooling techniques offer the promise of improving several broad classes of experiments with radioactive isotopes. In nuclear β decay, neutrino spectroscopy from beta-recoil coincidences, along with highly polarized samples, enable experiments to search for non-Standard Model interactions, test whether parity symmetry is maximally violated, and search for new sources of time reversal violation. Ongoing efforts at TRIUMF, Los Alamos and Berkeley will be highlighted. The traps also offer bright sources for Doppler-free spectroscopy, particularly in high-Z atoms where precision measurements could measure the strength of weak neutral nucleon-nucleon and electron-nucleon interactions. Physics with francium atoms has been vigorously pursued at Stony Brook. Several facilities plan work with radioactive atom traps; concrete plans and efforts at KVI Groningen and Legnaro will be among those summarized. Contributions to the multidisciplinary field of trace analysis will be left up to other presenters

  16. Neutral atom traps of radioactives

    CERN Document Server

    Behr, J A

    2003-01-01

    Neutral atoms trapped with modern laser cooling techniques offer the promise of improving several broad classes of experiments with radioactive isotopes. In nuclear beta decay, neutrino spectroscopy from beta-recoil coincidences, along with highly polarized samples, enable experiments to search for non-Standard Model interactions, test whether parity symmetry is maximally violated, and search for new sources of time reversal violation. Ongoing efforts at TRIUMF, Los Alamos and Berkeley will be highlighted. The traps also offer bright sources for Doppler-free spectroscopy, particularly in high-Z atoms where precision measurements could measure the strength of weak neutral nucleon-nucleon and electron-nucleon interactions. Physics with francium atoms has been vigorously pursued at Stony Brook. Several facilities plan work with radioactive atom traps; concrete plans and efforts at KVI Groningen and Legnaro will be among those summarized. Contributions to the multidisciplinary field of trace analysis will be left...

  17. Neutral particles identification at LHCb

    CERN Multimedia

    Quintana, Boris Julien

    2018-01-01

    Important analyses of the core LHCb physics program rely on calorimetry to identify photons, high-energy neutral pions and electrons. For this purpose, the LHCb calorimeter system is composed of a scintillating pad plane, a preshower detector, an electromagnetic and a hadronic sampling calorimeters. The interaction of a given particle in these detectors leaves a specific signature. This is exploited for particle identification (PID) by combining calorimeters and tracking information into multi-variate classifiers. In this contribution, we focus on the identification of photons against high-energy neutral pion and hadronic backgrounds. Performance on Run 1 data will be shown. Small discrepancies with simulation predictions are then discussed, with special emphasis on the methods to correctly estimate PID cut efficiencies by means of large calibration samples of abundant beauty and charm decays to final states with photons. Finally, the technical aspects of the collection of these samples in Run 2 are presented...

  18. Selective alkylation by photogenerated aryl and vinyl cation

    NARCIS (Netherlands)

    Slegt, Micha

    2006-01-01

    Seven para-substituted phenyl cations and the parent phenyl cation were prepared from iodonium salt precursors. Product studies revealed remarkable chemoselectivity and regioselectivity that could be related to the spin multiplicity of the cations. Also an universal method to fingerprint singlet and

  19. Vendor neutral archive in PACS

    International Nuclear Information System (INIS)

    Agarwal, Tapesh Kumar; Sanjeev

    2012-01-01

    An archive is a location containing a collection of records, documents, or other materials of historical importance. An integral part of Picture Archiving and Communication System (PACS) is archiving. When a hospital needs to migrate a PACS vendor, the complete earlier data need to be migrated in the format of the newly procured PACS. It is both time and money consuming. To address this issue, the new concept of vendor neutral archive (VNA) has emerged. A VNA simply decouples the PACS and workstations at the archival layer. This is achieved by developing an application engine that receives, integrates, and transmits the data using the different syntax of a Digital Imaging and Communication in Medicine (DICOM) format. Transferring the data belonging to the old PACS to a new one is performed by a process called migration of data. In VNA, a number of different data migration techniques are available to facilitate transfer from the old PACS to the new one, the choice depending on the speed of migration and the importance of data. The techniques include simple DICOM migration, prefetch-based DICOM migration, medium migration, and the expensive non-DICOM migration. “Vendor neutral” may not be a suitable term, and “architecture neutral,” “PACS neutral,” “content neutral,” or “third-party neutral” are probably better and preferred terms. Notwithstanding this, the VNA acronym has come to stay in both the medical IT user terminology and in vendor nomenclature, and radiologists need to be aware of its impact in PACS across the globe

  20. Electromagnetic disturbance neutralizing radiation detector

    International Nuclear Information System (INIS)

    Gripentog, W.G.

    1975-01-01

    A radiation detector of the Neher-White type is described which automatically neutralizes induced negative charges on the electrometer tube control grid which shut off the electrometer tube. The detector includes means for establishing a voltage of one polarity in response to plate current and voltage of opposite polarity in response to an absence of plate current and means for connecting the control grid to a reference potential for draining the negative charge in response to the voltage of opposite polarity. (author)

  1. Steady state neutral beam injector

    International Nuclear Information System (INIS)

    Mattoo, S.K.; Bandyopadhyay, M.; Baruah, U.K.; Bisai, N.; Chakbraborty, A.K.; Chakrapani, Ch.; Jana, M.R.; Bajpai, M.; Jaykumar, P.K.; Patel, D.; Patel, G.; Patel, P.J.; Prahlad, V.; Rao, N.V.M.; Rotti, C.; Singh, N.P.; Sridhar, B.

    2000-01-01

    Learning from operational reliability of neutral beam injectors in particular and various heating schemes including RF in general on TFTR, JET, JT-60, it has become clear that neutral beam injectors may find a greater role assigned to them for maintaining the plasma in steady state devices under construction. Many technological solutions, integrated in the present day generation of injectors have given rise to capability of producing multimegawatt power at many tens of kV. They have already operated for integrated time >10 5 S without deterioration in the performance. However, a new generation of injectors for steady state devices have to address to some basic issues. They stem from material erosion under particle bombardment, heat transfer > 10 MW/m 2 , frequent regeneration of cryopanels, inertial power supplies, data acquisition and control of large volume of data. Some of these engineering issues have been addressed to in the proposed neutral beam injector for SST-1 at our institute; the remaining shall have to wait for the inputs of the database generated from the actual experience with steady state injectors. (author)

  2. Neutral beams for magnetic fusion

    International Nuclear Information System (INIS)

    Hooper, B.

    1977-01-01

    Significant advances in forming energetic beams of neutral hydrogen and deuterium atoms have led to a breakthrough in magnetic fusion: neutral beams are now heating plasmas to thermonuclear temperatures, here at LLL and at other laboratories. For example, in our 2XIIB experiment we have injected a 500-A-equivalent current of neutral deuterium atoms at an average energy of 18 keV, producing a dense plasma (10 14 particles/cm 3 ) at thermonuclear energy (14 keV or 160 million kelvins). Currently, LLL and LBL are developing beam energies in the 80- to 120-keV range for our upcoming MFTF experiment, for the TFTR tokamak experiment at Princeton, and for the Doublet III tokamak experiment at General Atomic. These results increase our long-range prospects of producing high-intensity beams of energies in the hundreds or even thousands of kilo-electron-volts, providing us with optimistic extrapolations for realizing power-producing fusion reactors

  3. Radiation chemistry of aromatic dimer radical cations

    International Nuclear Information System (INIS)

    Okamoto, Kazumasa; Tagawa, Seiichi

    2009-01-01

    π-π Interactions of aromatic molecules are paid attention much in many fields, especially biology, chemistry, and applied physics, represented as protein, DNA, electron donor-accepter complexes, charge transfers, and self assembly molecules. Aromatic molecules including benzene rings are the simplest case to study the π-π interactions. To interpret the charge resonance (CR) structure in the dimer radical cations, spectroscopic and ESR methods have been carried out. The spectroscopic study on the dimer radical ion of molecules with two chromophores would be profitable to identify the electronic and configurational properties. In this article, dynamics of the dimer radical cation of benzenes, polystyrenes, and resist polymers is described on the basis of direct observation of CR band by the nanosecond pulse radiolysis and low temperature γ-radiolysis methods. (author)

  4. Electronic spectrum of 9-methylanthracenium radical cation

    Energy Technology Data Exchange (ETDEWEB)

    O’Connor, Gerard D.; Schmidt, Timothy W., E-mail: timothy.schmidt@unsw.edu.au [School of Chemistry, UNSW Sydney, New South Wales 2052 (Australia); Sanelli, Julian A.; Dryza, Vik; Bieske, Evan J. [School of Chemistry, The University of Melbourne, Victoria 3010 (Australia)

    2016-04-21

    The predissociation spectrum of the cold, argon-tagged, 9-methylanthracenium radical cation is reported from 8000 cm{sup −1} to 44 500 cm{sup −1}. The reported spectrum contains bands corresponding to at least eight electronic transitions ranging from the near infrared to the ultraviolet. These electronic transitions are assigned through comparison with ab initio energies and intensities. The infrared D{sub 1}←D{sub 0} transitions exhibit significant vibronic activity, which is assigned through comparison with TD-B3LYP excited state frequencies and intensities, as well as modelled vibronic interactions. Dissociation of 9-methylanthracenium is also observed at high visible-photon energies, resulting in the loss of either CH{sub 2} or CH{sub 3}. The relevance of these spectra, and the spectra of other polycyclic aromatic hydrocarbon radical cations, to the largely unassigned diffuse interstellar bands, is discussed.

  5. Photodissociation of spatially aligned acetaldehyde cations.

    Science.gov (United States)

    Lee, Suk Kyoung; Silva, Ruchira; Kim, Myung Hwa; Shen, Lei; Suits, Arthur G

    2007-07-26

    Photofragment translational energy and angular distributions are reported for the photodissociation of acetaldehyde cations in the wavelength range 354-363 nm obtained using the DC slice ion imaging technique. Vibrationally selected parent ions were produced by 2+1 resonance-enhanced multiphoton ionization (REMPI) via the 3sCH3CO+, and CH4+. The angular distributions reveal that all product channels have a predominantly parallel recoil anisotropy although the lower beta2 parameter of CH3CO+ indicates the concomitant presence of a perpendicular component. Furthermore, the distinct angular distribution of the CH3CO+ fragments shows a large value of the higher order Legendre polynomial term, providing evidence that acetaldehyde cations are spatially aligned during the ionization process.

  6. Mechanism of adsorption of cations onto rocks

    International Nuclear Information System (INIS)

    Kitamura, Akira; Yamamoto, Tadashi; Fujiwara, Kenso; Nishikawa, Sataro; Moriyama, Hirotake

    1999-01-01

    Adsorption behavior of cations onto granite was investigated. The distribution coefficient (K d ) of Sr 2+ and Ba 2+ onto granite was determined in the solution of which pH was ranged from 3.5 to 11.3 and ionic strength was set at 10 -2 and 10 -1 . The K d values were found to increase with increasing pH and with deceasing ionic strength. The obtained data were successfully analyzed by applying an electrical double layer model. The optimum parameter values of the double layer electrostatics and adsorption reactions were obtained, and the mechanism of adsorption of cations onto granite was discussed. Feldspar was found to play an important role in their adsorption. (author)

  7. Regulation of Cation Balance in Saccharomyces cerevisiae

    Science.gov (United States)

    Cyert, Martha S.; Philpott, Caroline C.

    2013-01-01

    All living organisms require nutrient minerals for growth and have developed mechanisms to acquire, utilize, and store nutrient minerals effectively. In the aqueous cellular environment, these elements exist as charged ions that, together with protons and hydroxide ions, facilitate biochemical reactions and establish the electrochemical gradients across membranes that drive cellular processes such as transport and ATP synthesis. Metal ions serve as essential enzyme cofactors and perform both structural and signaling roles within cells. However, because these ions can also be toxic, cells have developed sophisticated homeostatic mechanisms to regulate their levels and avoid toxicity. Studies in Saccharomyces cerevisiae have characterized many of the gene products and processes responsible for acquiring, utilizing, storing, and regulating levels of these ions. Findings in this model organism have often allowed the corresponding machinery in humans to be identified and have provided insights into diseases that result from defects in ion homeostasis. This review summarizes our current understanding of how cation balance is achieved and modulated in baker’s yeast. Control of intracellular pH is discussed, as well as uptake, storage, and efflux mechanisms for the alkali metal cations, Na+ and K+, the divalent cations, Ca2+ and Mg2+, and the trace metal ions, Fe2+, Zn2+, Cu2+, and Mn2+. Signal transduction pathways that are regulated by pH and Ca2+ are reviewed, as well as the mechanisms that allow cells to maintain appropriate intracellular cation concentrations when challenged by extreme conditions, i.e., either limited availability or toxic levels in the environment. PMID:23463800

  8. Reducible cationic lipids for gene transfer.

    Science.gov (United States)

    Wetzer, B; Byk, G; Frederic, M; Airiau, M; Blanche, F; Pitard, B; Scherman, D

    2001-01-01

    One of the main challenges of gene therapy remains the increase of gene delivery into eukaryotic cells. We tested whether intracellular DNA release, an essential step for gene transfer, could be facilitated by using reducible cationic DNA-delivery vectors. For this purpose, plasmid DNA was complexed with cationic lipids bearing a disulphide bond. This reduction-sensitive linker is expected to be reduced and cleaved in the reducing milieu of the cytoplasm, thus potentially improving DNA release and consequently transfection. The DNA--disulphide-lipid complexation was monitored by ethidium bromide exclusion, and the size of complexes was determined by dynamic light scattering. It was found that the reduction kinetics of disulphide groups in DNA--lipid complexes depended on the position of the disulphide linker within the lipid molecule. Furthermore, the internal structure of DNA--lipid particles was examined by small-angle X-ray scattering before and after lipid reduction. DNA release from lipid complexes was observed after the reduction of disulphide bonds of several lipids. Cell-transfection experiments suggested that complexes formed with selected reducible lipids resulted in up to 1000-fold higher reporter-gene activity, when compared with their analogues without disulphide bonds. In conclusion, reduction-sensitive groups introduced into cationic lipid backbones potentially allow enhanced DNA release from DNA--lipid complexes after intracellular reduction and represent a tool for improved vectorization. PMID:11389682

  9. Investigations on complexing cation exchangers and their use for trace analysis in natural waters

    International Nuclear Information System (INIS)

    Lang, H.

    1991-12-01

    The practicability of cation preconcentrations from natural waters by use of EDTrA- and 5-s-oxine- celluloses has been studied. For that purpose the protonation constants as well as the complexation capacities were determined by use of acid/base titrations. In additional titration experiments the complex stability constants for Cu 2+ , Mn 2+ , Co 2+ , Ni 2+ and Ca 2+ were determined examplarely. The interpretation of the experiments was performed using an optimised fit between calculated and experimentally determined pH-titration curves. Calculations have been done by the computer code 'MINEQL'. The determined stability constants are in the same order of magnitude as those given in literature for the water soluble complexes of EDTA, NTA or 5-s-oxine. The preconcentration of cations from natural water samples occurs in accordance with the theoretical predictions. Not ignorable disturbances appear for cations forming hydroxides or oxides in neutral or weakly acidic solutions. By use of radioactive isotopes for Sn 2+ , Zn 4+ and Nb 5+ it can be shown that those ions may form particles or colloids in natural waters. These particles will be filtered in the columns packed with the celluloses and can hardly be removed from there. (author)

  10. Tetrathiafulvalene-based azine ligands for anion and metal cation coordination

    Directory of Open Access Journals (Sweden)

    Awatef Ayadi

    2015-08-01

    Full Text Available The synthesis and full characterization of two tetrathiafulvalene-appended azine ligands, namely 2-([2,2’-bi(1,3-dithiolylidene]-4-yl-6-((2,4-dinitrophenylhydrazonomethylpyridine (L1 and 5-([2,2’-bi(1,3-dithiolylidene]-4-yl-2-((2,4-dinitrophenylhydrazonomethylpyridine (L2 are described. The crystal structure of ligand L1 indicates that the ligand is completely planar with the presence of a strong intramolecular N3–H3···O1 hydrogen bonding. Titration experiments with inorganic anions showed that both ligands are suitable candidates for the sensing of fluoride anions. Ligand L2 was reacted with a Re(I cation to yield the corresponding rhenium tricarbonyl complex 3. In the crystal structure of the newly prepared electroactive rhenium complex the TTF is neutral and the rhenium cation is hexacoordinated. The electrochemical behavior of the three compounds indicates that they are promising for the construction of crystalline radical cation salts.

  11. Exceptionally High Proton and Lithium Cation Gas-Phase Basicity of the Anti-Diabetic Drug Metformin.

    Science.gov (United States)

    Raczyńska, Ewa D; Gal, Jean-François; Maria, Pierre-Charles; Michalec, Piotr; Zalewski, Marcin

    2017-11-16

    Substituted biguanides are known for their biological effect, and a few of them are used as drugs, the most prominent example being metformin (1,1-dimethylbiguanide, IUPAC name: N,N-dimethylimidodicarbonimidic diamide). Because of the presence of hydrogen atoms at the amino groups, biguanides exhibit a multiple tautomerism. This aspect of their structures was examined in detail for unsubstituted biguanide and metformin in the gas phase. At the density functional theory (DFT) level {essentially B3LYP/6-311+G(d,p)}, the most stable structures correspond to the conjugated, push-pull, system (NR 2 )(NH 2 )C═N-C(═NH)NH 2 (R = H, CH 3 ), further stabilized by an internal hydrogen bond. The structural and energetic aspects of protonation and lithium cation adduct formation of biguanide and metformin was examined at the same level of theory. The gas-phase protonation energetics reveal that the more stable tautomer is protonated at the terminal imino C═NH site, still with an internal hydrogen bond maintaining the structure of the neutral system. The calculated proton affinity and gas-phase basicity of the two molecules reach the domain of superbasicity. By contrast, the lithium cation prefers to bind the less stable, not fully conjugated, tautomer (NR 2 )C(═NH)-NH-C(═NH)NH 2 of biguanides, in which the two C═NH groups are separated by NH. This less stable form of biguanides binds Li + as a bidentate ligand, in agreement with what was reported in the literature for other metal cations in the solid phase. The quantitative assessment of resonance in biguanide, in metformin and in their protonated forms, using the HOMED and HOMA indices, reveals an increase in electron delocalization upon protonation. On the contrary, the most stable lithium cation adducts are less conjugated than the stable neutral biguanides, because the metal cation is better coordinated by the not-fully conjugated bidentate tautomer.

  12. Plasma/Neutral-Beam Etching Apparatus

    Science.gov (United States)

    Langer, William; Cohen, Samuel; Cuthbertson, John; Manos, Dennis; Motley, Robert

    1989-01-01

    Energies of neutral particles controllable. Apparatus developed to produce intense beams of reactant atoms for simulating low-Earth-orbit oxygen erosion, for studying beam-gas collisions, and for etching semiconductor substrates. Neutral beam formed by neutralization and reflection of accelerated plasma on metal plate. Plasma ejected from coaxial plasma gun toward neutralizing plate, where turned into beam of atoms or molecules and aimed at substrate to be etched.

  13. The Neutral Interest Rate: Estimates for Chile

    OpenAIRE

    Rodrigo Fuentes S; Fabián Gredig U.

    2008-01-01

    To estimate the neutral real interest rate for Chile, we use a variety of methods that can be classified into three categories: those derived from economic theory, the neutral rate implicit in financial assets, and statistical procedures using macroeconomic data. We conclude that the neutral rate is not constant over time, but it is closely related with—though not equivalent to—the potential GDP growth rate. The application of the different methods yields fairly similar results. The neutral r...

  14. Neutrality in mediation: an ambiguous ethical value

    OpenAIRE

    Bailey, Paul

    2014-01-01

    Mediator neutrality would appear, by definition, to be a necessary and required ethical principle for all mediators to practice. But what is meant by neutrality in mediation? Is it practically possible to be completely neutral between parties in mediation while at the same time being fair to both of them? This paper attempts to answer these two questions.

  15. Ion-beam Plasma Neutralization Interaction Images

    International Nuclear Information System (INIS)

    Igor D. Kaganovich; Edward Startsev; S. Klasky; Ronald C. Davidson

    2002-04-01

    Neutralization of the ion beam charge and current is an important scientific issue for many practical applications. The process of ion beam charge and current neutralization is complex because the excitation of nonlinear plasma waves may occur. Computer simulation images of plasma neutralization of the ion beam pulse are presented

  16. Ion-beam Plasma Neutralization Interaction Images

    Energy Technology Data Exchange (ETDEWEB)

    Igor D. Kaganovich; Edward Startsev; S. Klasky; Ronald C. Davidson

    2002-04-09

    Neutralization of the ion beam charge and current is an important scientific issue for many practical applications. The process of ion beam charge and current neutralization is complex because the excitation of nonlinear plasma waves may occur. Computer simulation images of plasma neutralization of the ion beam pulse are presented.

  17. The Net Neutrality Debate: The Basics

    Science.gov (United States)

    Greenfield, Rich

    2006-01-01

    Rich Greenfield examines the basics of today's net neutrality debate that is likely to be an ongoing issue for society. Greenfield states the problems inherent in the definition of "net neutrality" used by Common Cause: "Network neutrality is the principle that Internet users should be able to access any web content they choose and…

  18. Anchoring cationic amphiphiles for nucleotide delivery: significance of DNA release from cationic liposomes for transfection.

    Science.gov (United States)

    Hirashima, Naohide; Minatani, Kazuhiro; Hattori, Yoshifumi; Ohwada, Tomohiko; Nakanishi, Mamoru

    2007-06-01

    We have designed and synthesized lithocholic acid-based cationic amphiphile molecules as components of cationic liposomes for gene transfection (lipofection). To study the relationship between the molecular structures of those amphiphilic molecules, particularly the extended hydrophobic appendant (anchor) at the 3-hydroxyl group, and transfection efficiency, we synthesized several lithocholic and isolithocholic acid derivatives, and examined their transfection efficiency. We also compared the physico-chemical properties of cationic liposomes prepared from these derivatives. We found that isolithocholic acid derivatives exhibit higher transfection efficiency than the corresponding lithocholic acid derivatives. This result indicates that the orientation and extension of hydrophobic regions influence the gene transfection process. Isolithocholic acid derivatives showed a high ability to encapsulate DNA in a compact liposome-DNA complex and to protect it from enzymatic degradation. Isolithocholic acid derivatives also facilitated the release of DNA from the liposome-DNA complex, which is a crucial step for DNA entry into the nucleus. Our results show that the transfection efficiency is directly influenced by the ability of the liposome complex to release DNA, rather than by the DNA-encapsulating ability. Molecular modeling revealed that isolithocholic acid derivatives take relatively extended conformations, while the lithocholic acid derivatives take folded structures. Thus, the efficiency of release of DNA from cationic liposomes in the cytoplasm, which contributes to high transfection efficiency, appears to be dependent upon the molecular shape of the cationic amphiphiles.

  19. Comparative analysis of cation/proton antiporter superfamily in plants.

    Science.gov (United States)

    Ye, Chu-Yu; Yang, Xiaohan; Xia, Xinli; Yin, Weilun

    2013-06-01

    The cation/proton antiporter superfamily is associated with the transport of monovalent cations across membranes. This superfamily was annotated in the Arabidopsis genome and some members were functionally characterized. In the present study, a systematic analysis of the cation/proton antiporter genes in diverse plant species was reported. We identified 240 cation/proton antiporters in alga, moss, and angiosperm. A phylogenetic tree was constructed showing these 240 members are separated into three families, i.e., Na(+)/H(+) exchangers, K(+) efflux antiporters, and cation/H(+) exchangers. Our analysis revealed that tandem and/or segmental duplications contribute to the expansion of cation/H(+) exchangers in the examined angiosperm species. Sliding window analysis of the nonsynonymous/synonymous substitution ratios showed some differences in the evolutionary fate of cation/proton antiporter paralogs. Furthermore, we identified over-represented motifs among these 240 proteins and found most motifs are family specific, demonstrating diverse evolution of the cation/proton antiporters among three families. In addition, we investigated the co-expressed genes of the cation/proton antiporters in Arabidopsis thaliana. The results showed some biological processes are enriched in the co-expressed genes, suggesting the cation/proton antiporters may be involved in these biological processes. Taken together, this study furthers our knowledge on cation/proton antiporters in plants. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Cation Exchange Capacity of Biochar: An urgent method modification

    Science.gov (United States)

    Munera, Jose; Martinsen, Vegard; Mulder, Jan; Tau Strand, Line; Cornelissen, Gerard

    2017-04-01

    A better understanding of the cation exchange capacity (CEC) values of biochar and its acid neutralizing capacity (ANC) is crucial when tailoring a single biochar for a particular soil and crop. Literature values for the CEC of biochar are surprisingly variable, commonly ranging from 5 to 50 cmol+/Kg even as high as 69 to 204 cmol+/Kg and often poorly reproducible, suggesting methodological problems. Ashes and very fine pores in biochar may complicate the analysis and thus compromise the results. Here, we modify and critically assess different steps in a common method for CEC determination in biochar and investigate how the measured CEC may be affected by slow cation diffusion from micro-pores. We modified the existing ammonium acetate (NH4-OAc) method (buffered at pH 7), based on displaced ammonium (NH4+) in potassium chloride (KCl) extracts after removing excess NH4-OAc with alcohol in batch mode. We used pigeon pea biochar (produced at 350 ˚C; particle size 0.5mm to 2mm) to develop the method and we tested its reproducibility in biochars with different ANC. The biochar sample (1.00g) was pH-adjusted to 7 after 2 days of equilibration, using hydrochloric acid (HCl), and washed with water until the conductivity of the water was modified method were highly reproducible and that 1 day shaking with NH4OAc and KCl is enough to saturate the exchange sites with NH4+ and subsequently with K+. The biochar to NH4OAc solution ratio did not affect the measured CEC. Three washings with at least 15 ml alcohol are required to remove excess NH4-OAc. We found the CEC of biochar with the displacement method from pigeon pea, corncob, rice husk and cacao shell to be 26.4(±0.3), 19.2(±0.5), 20.5(±0.4), 46.5±(0.2) cmol+/Kg, respectively. The selected batch experiment allows a large sample throughput, less laboratory equipment is needed and shaking ensures better contact between the extracting solution and the exchange sites.

  1. Neutralization of acidic raindrops on leaves of agricultural crop and boreal forest species

    Energy Technology Data Exchange (ETDEWEB)

    Hutchinson, T.C.; Adams, C.M.; Gaber, B.A.

    1986-10-01

    The abilities of foliage of selected agricultural crop and native boreal forest species to neutralize acidic raindrops were compared. The species differed widely in their responses. Neutralization was influenced to a large extent by leaf wettability and was poorly related with species' susceptibility to foliar injury from acid rain sprayings. Little neutralization of pH 3.0 droplets occurred on very waxy leaves, e.g. cabbage (Brassica oleracea L.), due to the small contact area between the leaf surface and raindrops. In contrast, on sunflower (Helianthus annuus L.) and radish (Raphanus sativus L.) leaves, which are pubescent and easily wettable, neutralization was considerable. For all agricultural crop species examined, the pH of droplets drying on cotyledons was consistently higher than on the leaves. The pH values of raindrops were also higher when the foliage was injured by the acid rain, probably due to leakage of cellular contents. Among boreal forest species examined, bunchberry (Cornus canadensis L.) was particularly good at neutralizing natural acid rain, increasing the pH from 3.9 to 6.6 after 9 hr of foliar contact, while the response of other boreal species ranged from a final pH of 4.8 to 5.7 under the same conditions. Simulated raindrops on wild sarsaparilla (Aralia nudicaulis L.) were never neutralized but increased in acidity as they evaporated. Chemical analyses of droplets collected from foliage showed calcium (Ca) and potassium (K) to be the major cations entering the neutralized droplets. Neutralization of acidic raindrops appears to occur through two processes; solubilization of alkaline dusts and exudates on the leaf surface, and ion exchange removal of H/sup +/ by the foliage. 14 references.

  2. Neutralization of acidic raindrops on leaves of agricultural crop and boreal forest species

    Energy Technology Data Exchange (ETDEWEB)

    Hutchinson, T.C.; Adams, C.M.; Gaber, B.A.

    1986-11-01

    The abilities of foliage of selected agricultural crop and native boreal forest species to neutralize acidic raindrops were compared. The species differed widely in their responses. Neutralization was influenced to a large extent by leaf wettability and was poorly related with species' susceptibility to foliar injury from acid rain sprayings. Little neutralization of pH 3.0 droplets occurred on very waxy leaves, e.g. cabbage (Brassica oleracea L.), due to the small contact area between the leaf surface and raindrops. In contrast, on sunflower (Helianthus annuus L.) and radish (Raphanus sativus L.) leaves, which are pubescent and easily wettable, neutralization was considerable. For all agricultural crop species examined, the pH of droplets drying on cotyledons was consistently higher than on the leaves. The pH values of raindrops were also higher when the foliage was injured by the acid rain, probably due to leakage of cellular contents. Among boreal forest species examined, bunchberry (Cornus canadensis L.) was particularly good at neutralizing natural acid rain, increasing the pH from 3.9 to 6.6 after 9 hr of foliar contact, while the response of other boreal species ranged from a final pH of 4.8 to 5.7 under the same conditions. Simulated raindrops on wild sarsaparilla (Aralia nudicaulis L.) were never neutralized but increased in acidity as they evaporated. Chemical analyses of droplets collected from foliage showed calcium and potassium to be the major cations entering the neutralized droplets. Neutralization of acidic raindrops appears to occur through two processes: solubilization of alkaline dusts and exudates on the leaf surface, and ion exchange removal of H/sup +/ by the foliage. 14 refs.

  3. Characterization of a distonic isomer C6H5C+(OH)OCH2 of methyl benzoate radical cation by associative ion-molecule reactions

    Science.gov (United States)

    Dechamps, Noémie; Flammang, Robert; Gerbaux, Pascal; Nam, Pham-Cam; Nguyen, Minh Tho

    2006-03-01

    The C6H5C+(OH)OCH2 radical cation, formally a distonic isomer of ionized methyl benzoate, has been prepared by dissociative ionization of neopentyl benzoate, as earlier suggested by Audier et al. [H.E. Audier, A. Milliet, G. Sozzi, S. Hammerum, Org. Mass. Spectrom. 25 (1990) 44]. Its distonic character has now been firmly established by its high reactivity towards neutral methyl isocyanide (ionized methylene transfer) producing N-methyl ketenimine ions. Other mass spectrometric experiments and ab initio quantum chemical calculations also concur with each other pointing toward the existence of a stable distonic radical cation.

  4. Radical cations of quadricyclane and norbornadiene in polar ZSM-5 matrices: Radical cation photochemical transformations without photons

    International Nuclear Information System (INIS)

    Barnabas, M.V.; Trifunac, A.D.

    1994-01-01

    Radical cations of quadricyclane (Q) and norbornadiene (NBD) are produced by γ-radiolysis in zeolites. In polar ZSM-5, only one radical cation is initially observed below 100K. Increasing the temperature above 200K gives rise to the cyclopentadiene radical cation. Higher temperatures (>360K) give rise to the cyclopenten-4-yl radical. The observation of cyclopentadiene radical cation implies the occurrence of the reverse Diels-Alder reaction. This is a thermally forbidden, photochemically allowed, process, which is made possible by the interaction of the polar zeolite matrix sites with parent NBD and Q radical cations

  5. Advanced neutral-beam technology

    International Nuclear Information System (INIS)

    Berkner, K.H.

    1980-09-01

    Extensive development will be required to achieve the 50- to 75-MW, 175- to 200-keV, 5- to 10-sec pulses of deuterium atoms envisioned for ETF and INTOR. Multi-megawatt injector systems are large (and expansive); they consist of large vacuum tanks with many square meters of cryogenic pumping panels, beam dumps capable of dissipating several megawatts of un-neutralized beam, bending magnets, electrical power systems capable of fast turnoff with low (capacity) stored energy, and, of course, the injector modules (ion sources and accelerators). The technology requirements associated with these components are described

  6. Plasma neutralizers for H- or D- beams

    International Nuclear Information System (INIS)

    Berkner, K.H.; Pyle, R.V.; Savas, S.E.; Stalder, K.R.

    1980-10-01

    Plasma neutralizers can produce higher conversion efficiencies than are obtainable with gas neutralizers for the production of high-energy neutral beams from negative hydrogen ions. Little attention has been paid to experimental neutralizer studies because of the more critical problems connected with the development of negative-ion sources. With the prospect of accelerating ampere dc beams from extrapolatable ion sources some time next year, we are re-examining plasma neutralizers. Some basic considerations, two introductory experiments, and a next-step experiment are described

  7. ORNL positive ion neutral beam program

    International Nuclear Information System (INIS)

    Whealton, J.H.; Haselton, H.H.; Barber, G.C.

    1978-01-01

    The neutral beam group at Oak Ridge National Laboratory has constructed neutral beam generators for the ORMAK and PLT devices, is presently constructing neutral beam devices for the ISX and PDX devices, and is contemplating the construction of neutral beam systems for the advanced TNS device. These neutral beam devices stem from the pioneering work on ion sources of G. G. Kelley and O. B. Morgan. We describe the ion sources under development at this Laboratory, the beam optics exhibited by these sources, as well as some theoretical considerations, and finally the remainder of the beamline design

  8. Cationic niosomes an effective gene carrier composed of novel spermine-derivative cationic lipids: effect of central core structures.

    Science.gov (United States)

    Opanasopit, Praneet; Leksantikul, Lalita; Niyomtham, Nattisa; Rojanarata, Theerasak; Ngawhirunpat, Tanasait; Yingyongnarongkul, Boon-Ek

    2017-05-01

    Cationic niosomes formulated from Span 20, cholesterol (Chol) and novel spermine-based cationic lipids of multiple central core structures (di(oxyethyl)amino, di(oxyethyl)amino carboxy, 3-amino-1,2-dioxypropyl and 2-amino-1,3-dioxypropyl) were successfully prepared for improving transfection efficiency in vitro. The niosomes composed of spermine cationic lipid with central core structure of di(oxyethyl)amino revealed the highest gene transfection efficiency. To investigate the factors affecting gene transfection and cell viability including differences in the central core structures of cationic lipids, the composition of vesicles, molar ratio of cationic lipids in formulations and the weight ratio of niosomes to DNA. Cationic niosomes composed of nonionic surfactants (Span20), cholesterol and spermine-based cationic lipids of multiple central core structures were formulated. Gene transfection and cell viability were evaluated on a human cervical carcinoma cell line (HeLa cells) using pDNA encoding green fluorescent protein (pEGFP-C2). The morphology, size and charge were also characterized. High transfection efficiency was obtained from cationic niosomes composed of Span20:Chol:cationic lipid at the molar ratio of 2.5:2.5:0.5 mM. Cationic lipids with di(oxyethyl)amino as a central core structure exhibited highest transfection efficiency. In addition, there was also no serum effect on transfection efficiency. These novel cationic niosomes may constitute a good alternative carrier for gene transfection.

  9. Discrete symmetries with neutral mesons

    Science.gov (United States)

    Bernabéu, José

    2018-01-01

    Symmetries, and Symmetry Breakings, in the Laws of Physics play a crucial role in Fundamental Science. Parity and Charge Conjugation Violations prompted the consideration of Chiral Fields in the construction of the Standard Model, whereas CP-Violation needed at least three families of Quarks leading to Flavour Physics. In this Lecture I discuss the Conceptual Basis and the present experimental results for a Direct Evidence of Separate Reversal-in-Time T, CP and CPT Genuine Asymmetries in Decaying Particles like Neutral Meson Transitions, using Quantum Entanglement and the Decay as a Filtering Measurement. The eight transitions associated to the Flavour-CP eigenstate decay products of entangled neutral mesons have demonstrated with impressive significance a separate evidence of TRV and CPV in Bd-physics, whereas a CPTV asymmetry shows a 2σ effect interpreted as an upper limit. Novel CPTV observables are discussed for K physics at KLOE-2, including the difference between the semileptonic asymmetries from KL and KS, the ratios of double decay rate Intensities to Flavour-CP eigenstate decay products and the ω-effect. Their observation would lead to a change of paradigm beyond Quantum Field Theory, however there is nothing in Quantum Mechanics forbidding CPTV.

  10. Cation-Cation Complexes of Pentavalent Uranyl: From Disproportionation Intermediates to Stable Clusters

    Energy Technology Data Exchange (ETDEWEB)

    Mougel, Victor; Horeglad, Pawel; Nocton, Gregory; Pecaut, Jacques; Mazzanti, Marinella [CEA, INAC, SCIB, Laboratoire de Reconnaissance Ionique et Chimie de Coordination, CEA-Grenoble, 38054 GRENOBLE, Cedex 09 (France)

    2010-07-01

    Three new cation cation complexes of pentavalent uranyl, stable with respect to the disproportionation reaction, have been prepared from the reaction of the precursor [(UO{sub 2}py{sub 5})-(KI{sub 2}py{sub 2})]{sub n} (1) with the Schiff base ligands salen{sup 2-}, acacen{sup 2-}, and salophen{sup 2-} (H{sub 2}salen N, N'-ethylene-bis(salicylidene-imine), H{sub 2}acacen=-N, N'-ethylenebis(acetylacetone-imine), H{sub 2}salophen=N, N'-phenylene-bis(salicylidene-imine)). The preparation of stable complexes requires a careful choice of counter ions and reaction conditions. Notably the reaction of 1 with salophen{sup 2-} in pyridine leads to immediate disproportionation, but in the presence of [18]crown-6 ([18]C-6) a stable complex forms. The solid-state structure of the four tetra-nuclear complexes ([UO{sub 2}-(acacen)]{sub 4}[{mu}{sub 8}-]{sub 2}[K([18]C-6)(py)]{sub 2}) (3) and ([UO{sub 2}(acacen)](4)[{mu}{sub 8}-]).2[K([222])(py)] (4) ([UO{sub 2}(salophen)](4)[{mu}{sub 8}-K]{sub 2}[mu(5)-KI]{sub 2}[(K([18]C-6)]).2 [K([18]C-6)-(thf){sub 2}].2I (5), and ([UO{sub 2}(salen)(4)][{mu}{sub 8}-Rb]{sub 2}[Rb([18]C-6)]{sub 2}) (9) ([222] = [222]cryptand, py =pyridine), presenting a T-shaped cation cation interaction has been determined by X-ray crystallographic studies. NMR spectroscopic and UV/Vis studies show that the tetra-nuclear structure is maintained in pyridine solution for the salen and acacen complexes. Stable mononuclear complexes of pentavalent uranyl are also obtained by reduction of the hexavalent uranyl Schiff base complexes with cobaltocene in pyridine in the absence of coordinating cations. The reactivity of the complex [U{sup V}O{sub 2}(salen)(py)][Cp*{sub 2}Co] with different alkali ions demonstrates the crucial effect of coordinating cations on the stability of cation cation complexes. The nature of the cation plays a key role in the preparation of stable cation cation complexes. Stable tetra-nuclear complexes form in the presence of K

  11. pH-Sensitive self-propelled motion of oil droplets in the presence of cationic surfactants containing hydrolyzable ester linkages.

    Science.gov (United States)

    Banno, Taisuke; Kuroha, Rie; Toyota, Taro

    2012-01-17

    Self-propelled oil droplets in a nonequilibrium system have drawn much attention as both a primitive type of inanimate chemical machinery and a dynamic model of the origin of life. Here, to create the pH-sensitive self-propelled motion of oil droplets, we synthesized cationic surfactants containing hydrolyzable ester linkages. We found that n-heptyloxybenzaldehyde oil droplets were self-propelled in the presence of ester-containing cationic surfactant. In basic solution prepared with sodium hydroxide, oil droplets moved as molecular aggregates formed on their surface. Moreover, the self-propelled motion in the presence of the hydrolyzable cationic surfactant lasted longer than that in the presence of nonhydrolyzable cationic surfactant. This is probably due to the production of a fatty acid by the hydrolysis of the ester-containing cationic surfactant and the subsequent neutralization of the fatty acid with sodium hydroxide. A complex surfactant was formed in the aqueous solution because of the cation and anion combination. Because such complex formation can induce both a decrease in the interfacial tension of the oil droplet and self-assembly with n-heptyloxybenzaldehyde and lauric acid in the aqueous dispersion, the prolonged movement of the oil droplet may be explained by the increase in heterogeneity of the interfacial tension of the oil droplet triggered by the hydrolysis of the ester-containing surfactant. © 2011 American Chemical Society

  12. Complexes of natural carbohydrates with metal cations

    International Nuclear Information System (INIS)

    Alekseev, Yurii E; Garnovskii, Alexander D; Zhdanov, Yu A

    1998-01-01

    Data on the interaction of natural carbohydrates (mono-, oligo-, and poly-saccharides, amino sugars, and natural organic acids of carbohydrate origin) with metal cations are surveyed and described systematically. The structural diversity of carbohydrate metal complexes, caused by some specific features of carbohydrates as ligands, is demonstrated. The influence of complex formation on the chemical properties of carbohydrates is discussed. It is shown that the formation of metal complexes plays an important role in the configurational and conformational analysis of carbohydrates. The practical significance of the coordination interaction in the series of carbohydrate ligands is demonstrated. The bibliography includes 571 references.

  13. Complex Macromolecular Architectures by Living Cationic Polymerization

    KAUST Repository

    Alghamdi, Reem D.

    2015-05-01

    Poly (vinyl ether)-based graft polymers have been synthesized by the combination of living cationic polymerization of vinyl ethers with other living or controlled/ living polymerization techniques (anionic and ATRP). The process involves the synthesis of well-defined homopolymers (PnBVE) and co/terpolymers [PnBVE-b-PCEVE-b-PSiDEGVE (ABC type) and PSiDEGVE-b-PnBVE-b-PSiDEGVE (CAC type)] by sequential living cationic polymerization of n-butyl vinyl ether (nBVE), 2-chloroethyl vinyl ether (CEVE) and tert-butyldimethylsilyl ethylene glycol vinyl ether (SiDEGVE), using mono-functional {[n-butoxyethyl acetate (nBEA)], [1-(2-chloroethoxy) ethyl acetate (CEEA)], [1-(2-(2-(t-butyldimethylsilyloxy)ethoxy) ethoxy) ethyl acetate (SiDEGEA)]} or di-functional [1,4-cyclohexanedimethanol di(1-ethyl acetate) (cHMDEA), (VEMOA)] initiators. The living cationic polymerizations of those monomers were conducted in hexane at -20 0C using Et3Al2Cl3 (catalyst) in the presence of 1 M AcOEt base.[1] The PCEVE segments of the synthesized block terpolymers were then used to react with living macroanions (PS-DPE-Li; poly styrene diphenyl ethylene lithium) to afford graft polymers. The quantitative desilylation of PSiDEGVE segments by n-Bu4N+F- in THF at 0 °C led to graft co- and terpolymers in which the polyalcohol is the outer block. These co-/terpolymers were subsequently subjected to “grafting-from” reactions by atom transfer radical polymerization (ATRP) of styrene to afford more complex macromolecular architectures. The base assisted living cationic polymerization of vinyl ethers were also used to synthesize well-defined α-hydroxyl polyvinylether (PnBVE-OH). The resulting polymers were then modified into an ATRP macro-initiator for the synthesis of well-defined block copolymers (PnBVE-b-PS). Bifunctional PnBVE with terminal malonate groups was also synthesized and used as a precursor for more complex architectures such as H-shaped block copolymer by “grafting-from” or

  14. Homogeneous cation exchange membrane by radiation grafting

    International Nuclear Information System (INIS)

    Kolhe, Shailesh M.; G, Agathian; Ashok Kumar

    2001-01-01

    Preparation of a strong cation exchange membrane by radiation grafting of styrene on to polyethylene (LDPE) film by mutual irradiation technique in the presence of air followed by sulfonation is described. The grafting has been carried out in the presence of air and without any additive. Low dose rate has been seen to facilitate the grafting. Further higher the grafting percentage more is the exchange capacity. The addition of a swelling agent during the sulfonation helped in achieving the high exchange capacity. The TGA-MASS analysis confirmed the grafting and the sulfonation. (author)

  15. Catalytic copolymerization of CO and ethylene with a charge neutral palladium(II) zwitterion.

    Science.gov (United States)

    Lu, Connie C; Peters, Jonas C

    2002-05-15

    The synthesis of a zwitterionic Pd(II) complex supported by an anionic bis(phosphino)borate ligand, Ph(2)B(CH(2)PPh(2))(2) (abbreviated as [Ph(2)BP(2)]), is reported. The new complex, [Ph(2)BP(2)]PdMe(THF), is active for CO and ethylene copolymerization. The copolymerization activity and polyketone molecular weight for the neutral, zwitterionic system are compared with those for the cationic systems [R(2)E(CH(2)PPh(2))(2)PdMe(THF)][B(C(6)F(5))(4)] where ER(2) = SiPh(2) and CH(2). Surprisingly, the more electron rich zwitterionic system is a catalyst of activity comparable to that of the more conventional cationic systems.

  16. Cationic polymers in water treatment: Part 1: Treatability of water with cationic polymers

    Czech Academy of Sciences Publication Activity Database

    Polasek, P.; Mutl, Silvestr

    2002-01-01

    Roč. 28, č. 1 (2002), s. 69-82 ISSN 0378-4738 R&D Projects: GA AV ČR KSK2067107 Keywords : cationic polymers * treatability * water quality Subject RIV: BK - Fluid Dynamics Impact factor: 0.481, year: 2002

  17. Cobalt 60 cation exchange with mexican clays

    International Nuclear Information System (INIS)

    Nava Galve, R.G.

    1993-01-01

    Mexican clays can be used to remove radioactive elements from contaminated aqueous solutions. Cation exchange experiments were performed with 60 Co radioactive solution. In the present work the effect of contact time on the sorption of Co 2+ was studied. The contact time in hydrated montmorillonite was from 5 to 120 minutes and in dehydrated montmorillonite 5 to 1400 minutes. The Co 2+ uptake value was, in hydrated montmorillonite, between 0.3 to 0.85 m eq/g and in dehydrated montmorillonite, between 0.6 to 1.40 m eq/g. The experiments were done in a pH 5.1 to 5.7 and normal conditions. XRD patterns were used to characterize the samples. The crystallinity was determined by X-ray Diffraction and it was maintained before and after the cation exchange. DTA thermo grams showed the temperatures of the lost humidity and crystallization water. Finally, was observed that dehydrated montmorillonite adsorb more cobalt than hydrated montmorillonite. (Author)

  18. Cationic antimicrobial peptides in penaeid shrimp.

    Science.gov (United States)

    Tassanakajon, Anchalee; Amparyup, Piti; Somboonwiwat, Kunlaya; Supungul, Premruethai

    2011-08-01

    Penaeid shrimp aquaculture has been consistently affected worldwide by devastating diseases that cause a severe loss in production. To fight a variety of harmful microbes in the surrounding environment, particularly at high densities (of which intensive farming represents an extreme example), shrimps have evolved and use a diverse array of antimicrobial peptides (AMPs) as part of an important first-line response of the host defense system. Cationic AMPs in penaeid shrimps composed of penaeidins, crustins, and anti-lipopolysaccharide factors are comprised of multiple classes or isoforms and possess antibacterial and antifungal activities against different strains of bacteria and fungi. Shrimp AMPs are primarily expressed in circulating hemocytes, which is the main site of the immune response, and hemocytes expressing AMPs probably migrate to infection sites to fight against pathogen invasion. Indeed, most AMPs are produced as early as the nauplii developmental stage to protect shrimp larvae from infections. In this review, we discuss the sequence diversity, expression, gene structure, and antimicrobial activities of cationic AMPs in penaeid shrimps. The information available on antimicrobial activities indicates that these shrimp AMPs have potential therapeutic applications in the control of disease problems in aquaculture.

  19. Cationic Antimicrobial Polymers and Their Assemblies

    Science.gov (United States)

    Carmona-Ribeiro, Ana Maria; de Melo Carrasco, Letícia Dias

    2013-01-01

    Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs). The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications. PMID:23665898

  20. Cationic Antimicrobial Polymers and Their Assemblies

    Directory of Open Access Journals (Sweden)

    Ana Maria Carmona-Ribeiro

    2013-05-01

    Full Text Available Cationic compounds are promising candidates for development of antimicrobial agents. Positive charges attached to surfaces, particles, polymers, peptides or bilayers have been used as antimicrobial agents by themselves or in sophisticated formulations. The main positively charged moieties in these natural or synthetic structures are quaternary ammonium groups, resulting in quaternary ammonium compounds (QACs. The advantage of amphiphilic cationic polymers when compared to small amphiphilic molecules is their enhanced microbicidal activity. Besides, many of these polymeric structures also show low toxicity to human cells; a major requirement for biomedical applications. Determination of the specific elements in polymers, which affect their antimicrobial activity, has been previously difficult due to broad molecular weight distributions and random sequences characteristic of radical polymerization. With the advances in polymerization control, selection of well defined polymers and structures are allowing greater insight into their structure-antimicrobial activity relationship. On the other hand, antimicrobial polymers grafted or self-assembled to inert or non inert vehicles can yield hybrid antimicrobial nanostructures or films, which can act as antimicrobials by themselves or deliver bioactive molecules for a variety of applications, such as wound dressing, photodynamic antimicrobial therapy, food packing and preservation and antifouling applications.

  1. Happy birthday, little neutral one

    International Nuclear Information System (INIS)

    Sutton, C.

    1990-01-01

    This article looks at the history of the neutrino particle, a tiny neutral particle which reacts only with the weak force. Its existence was originally postulated by Wolfgang Pauli in 1930, to explain beta decay energy conservation but because of the extreme experimental difficulties involved, neutrinos were not observed experimentally until 1956. Notwithstanding this the neutrino has become a valuable tool in high energy physics. Neutrino beams are used to probe matter and were used to reveal the existence of quarks within the particles once viewed as elementary, the proton and neutron. Cosmic neutrinos may be detected in the Deep Underwater Muon and Neutrino Detector off the coast of Hawaii and the Moon itself is a target for ultra high energy neutrinos in a Russian experiment to detect cascades of charge particles produced by these neutrinos in ice in the Antarctic. (UK)

  2. Gargamelle and the neutral currents

    International Nuclear Information System (INIS)

    Rousset, A.

    1996-06-01

    In order to simplify the description of forces, the physicists want to reduce the number of four interactions to a smaller one. They want to unify them. Einstein tried to unify the electromagnetic interaction and the gravitation interaction but it was probably the most difficult to unify. during the sixties, the American physicists Sheldon Glashow and Steven Weinberg and the Pakistani Abdus Salam ( each rewarded by the Nobel price of 1979) propose to unify the weak and electromagnetic interactions interactions under the form of an only interaction, the electro-weak interaction. To check the validity of this theory exist the demonstration by the weak neutral currents. In 1973, European physicians which analyzed photos taken in the bubble chamber called Gargamelle brought the experimental proof. This book tells the story of this discovery. (N.C.)

  3. $\\tau$ decays with neutral kaons

    CERN Document Server

    Abbiendi, G.; Akesson, P.F.; Alexander, G.; Allison, John; Anderson, K.J.; Arcelli, S.; Asai, S.; Ashby, S.F.; Axen, D.; Azuelos, G.; Bailey, I.; Ball, A.H.; Barberio, E.; Barlow, Roger J.; Batley, J.R.; Baumann, S.; Behnke, T.; Bell, Kenneth Watson; Bella, G.; Bellerive, A.; Bentvelsen, S.; Bethke, S.; Betts, S.; Biebel, O.; Biguzzi, A.; Bloodworth, I.J.; Bock, P.; Bohme, J.; Boeriu, O.; Bonacorsi, D.; Boutemeur, M.; Braibant, S.; Bright-Thomas, P.; Brigliadori, L.; Brown, Robert M.; Burckhart, H.J.; Capiluppi, P.; Carnegie, R.K.; Carter, A.A.; Carter, J.R.; Chang, C.Y.; Charlton, David G.; Chrisman, D.; Ciocca, C.; Clarke, P.E.L.; Clay, E.; Cohen, I.; Conboy, J.E.; Cooke, O.C.; Couchman, J.; Couyoumtzelis, C.; Coxe, R.L.; Cuffiani, M.; Dado, S.; Dallavalle, G.Marco; Dallison, S.; Davis, R.; de Roeck, A.; Dervan, P.; Desch, K.; Dienes, B.; Dixit, M.S.; Donkers, M.; Dubbert, J.; Duchovni, E.; Duckeck, G.; Duerdoth, I.P.; Estabrooks, P.G.; Etzion, E.; Fabbri, F.; Fanfani, A.; Fanti, M.; Faust, A.A.; Feld, L.; Ferrari, P.; Fiedler, F.; Fierro, M.; Fleck, I.; Frey, A.; Furtjes, A.; Futyan, D.I.; Gagnon, P.; Gary, J.W.; Gaycken, G.; Geich-Gimbel, C.; Giacomelli, G.; Giacomelli, P.; Gingrich, D.M.; Glenzinski, D.; Goldberg, J.; Gorn, W.; Grandi, C.; Graham, K.; Gross, E.; Grunhaus, J.; Gruwe, M.; Hajdu, C.; Hanson, G.G.; Hansroul, M.; Hapke, M.; Harder, K.; Harel, A.; Hargrove, C.K.; Harin-Dirac, M.; Hauschild, M.; Hawkes, C.M.; Hawkings, R.; Hemingway, R.J.; Herten, G.; Heuer, R.D.; Hildreth, M.D.; Hill, J.C.; Hobson, P.R.; Hocker, James Andrew; Hoffman, Kara Dion; Homer, R.J.; Honma, A.K.; Horvath, D.; Hossain, K.R.; Howard, R.; Huntemeyer, P.; Igo-Kemenes, P.; Imrie, D.C.; Ishii, K.; Jacob, F.R.; Jawahery, A.; Jeremie, H.; Jimack, M.; Jones, C.R.; Jovanovic, P.; Junk, T.R.; Kanaya, N.; Kanzaki, J.; Karapetian, G.; Karlen, D.; Kartvelishvili, V.; Kawagoe, K.; Kawamoto, T.; Kayal, P.I.; Keeler, R.K.; Kellogg, R.G.; Kennedy, B.W.; Kim, D.H.; Klier, A.; Kobayashi, T.; Kobel, M.; Kokott, T.P.; Kolrep, M.; Komamiya, S.; Kowalewski, Robert V.; Kress, T.; Krieger, P.; von Krogh, J.; Kuhl, T.; Kupper, M.; Kyberd, P.; Lafferty, G.D.; Landsman, H.; Lanske, D.; Lauber, J.; Lawson, I.; Layter, J.G.; Lellouch, D.; Letts, J.; Levinson, L.; Liebisch, R.; Lillich, J.; List, B.; Littlewood, C.; Lloyd, A.W.; Lloyd, S.L.; Loebinger, F.K.; Long, G.D.; Losty, M.J.; Lu, J.; Ludwig, J.; Macchiolo, A.; Macpherson, A.; Mader, W.; Mannelli, M.; Marcellini, S.; Marchant, T.E.; Martin, A.J.; Martin, J.P.; Martinez, G.; Mashimo, T.; Mattig, Peter; McDonald, W.John; McKenna, J.; Mckigney, E.A.; McMahon, T.J.; McPherson, R.A.; Meijers, F.; Mendez-Lorenzo, P.; Merritt, F.S.; Mes, H.; Meyer, I.; Michelini, A.; Mihara, S.; Mikenberg, G.; Miller, D.J.; Mohr, W.; Montanari, A.; Mori, T.; Nagai, K.; Nakamura, I.; Neal, H.A.; Nisius, R.; O'Neale, S.W.; Oakham, F.G.; Odorici, F.; Ogren, H.O.; Okpara, A.; Oreglia, M.J.; Orito, S.; Pasztor, G.; Pater, J.R.; Patrick, G.N.; Patt, J.; Perez-Ochoa, R.; Petzold, S.; Pfeifenschneider, P.; Pilcher, J.E.; Pinfold, J.; Plane, David E.; Poli, B.; Polok, J.; Przybycien, M.; Quadt, A.; Rembser, C.; Rick, H.; Robins, S.A.; Rodning, N.; Roney, J.M.; Rosati, S.; Roscoe, K.; Rossi, A.M.; Rozen, Y.; Runge, K.; Runolfsson, O.; Rust, D.R.; Sachs, K.; Saeki, T.; Sahr, O.; Sang, W.M.; Sarkisian, E.K.G.; Sbarra, C.; Schaile, A.D.; Schaile, O.; Scharff-Hansen, P.; Schieck, J.; Schmitt, S.; Schoning, A.; Schroder, Matthias; Schumacher, M.; Schwick, C.; Scott, W.G.; Seuster, R.; Shears, T.G.; Shen, B.C.; Shepherd-Themistocleous, C.H.; Sherwood, P.; Siroli, G.P.; Skuja, A.; Smith, A.M.; Snow, G.A.; Sobie, R.; Soldner-Rembold, S.; Spagnolo, S.; Sproston, M.; Stahl, A.; Stephens, K.; Stoll, K.; Strom, David M.; Strohmer, R.; Surrow, B.; Talbot, S.D.; Taras, P.; Tarem, S.; Teuscher, R.; Thiergen, M.; Thomas, J.; Thomson, M.A.; Torrence, E.; Towers, S.; Trefzger, T.; Trigger, I.; Trocsanyi, Z.; Tsur, E.; Turner-Watson, M.F.; Ueda, I.; Van Kooten, Rick J.; Vannerem, P.; Verzocchi, M.; Voss, H.; Wackerle, F.; Waller, D.; Ward, C.P.; Ward, D.R.; Watkins, P.M.; Watson, A.T.; Watson, N.K.; Wells, P.S.; Wengler, T.; Wermes, N.; Wetterling, D.; White, J.S.; Wilson, G.W.; Wilson, J.A.; Wyatt, T.R.; Yamashita, S.; Zacek, V.; Zer-Zion, D.

    2000-01-01

    The branching ratio of the tau lepton to a neutral K meson is measured from a sample of approximately 200,000 tau decays recorded by the OPAL detector at centre-of-mass energies near the Z0 resonance. The measurement is based on two samples which identify one-prong tau decays with KL and KS mesons. The combined branching ratios are measured to be B(tau- -->pi- K0bar nutau) = (9.33+-0.68+-0.49)x10^-3 B(tau- -->pi- K0bar [>=1pi0] nutau) = (3.24+-0.74+-0.66)x10^-3 B(tau- -->K- K0bar [>=0pi0] nutau) = (3.30+-0.55+-0.39)x10^-3 where the first error is statistical and the second systematic.

  4. Laser sputter neutral mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    King, B V; Clarke, M; Hu, H; Betz, [Newcastle Univ., NSW (Australia). Dept. of Physics

    1994-12-31

    Laser sputter neutral mass spectrometry (LSNMS) is an emerging technique for highly sensitive surface analysis. In this technique a target is bombarded with a pulsed beam of keV ions. The sputtered particles are intercepted by a high intensity pulsed laser beam above the surface and ionised with almost 100% efficiency. The photions may then be mass analysed using a quadrupole or, more commonly, using time of flight (TOF) techniques. In this method photoions are extracted from the ionisation region, accelerated to a known energy E{sub o} and strike a channelplate detector a distance `d` away. The flight time `t` of the photoions is then related to their mass by `d` {radical}m / {radical} 2E{sub o} so measurement of `t` allows mass spectra to be obtained. It is found that LSNMS is an emerging technique of great sensitivity and flexibility, useful for both applied analysis and to investigate basic sputtering processes. 4 refs., 3 figs.

  5. Laser sputter neutral mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    King, B.V.; Clarke, M.; Hu, H.; Betz [Newcastle Univ., NSW (Australia). Dept. of Physics

    1993-12-31

    Laser sputter neutral mass spectrometry (LSNMS) is an emerging technique for highly sensitive surface analysis. In this technique a target is bombarded with a pulsed beam of keV ions. The sputtered particles are intercepted by a high intensity pulsed laser beam above the surface and ionised with almost 100% efficiency. The photions may then be mass analysed using a quadrupole or, more commonly, using time of flight (TOF) techniques. In this method photoions are extracted from the ionisation region, accelerated to a known energy E{sub o} and strike a channelplate detector a distance `d` away. The flight time `t` of the photoions is then related to their mass by `d` {radical}m / {radical} 2E{sub o} so measurement of `t` allows mass spectra to be obtained. It is found that LSNMS is an emerging technique of great sensitivity and flexibility, useful for both applied analysis and to investigate basic sputtering processes. 4 refs., 3 figs.

  6. TFTR neutral beam power system

    International Nuclear Information System (INIS)

    Deitz, A.; Murray, H.; Winje, R.

    1977-01-01

    The TFTR NB System will be composed of four beam lines, each containing three ion sources presently being developed for TFTR by the Lawrence Berkeley Laboratories (LBL). The Neutral Beam Power System (NBPS) will provide the necessary power required to operate these Ion Sources in both an experimental or operational mode as well as test mode. This paper describes the technical as well as the administrative/management aspects involved in the development and building of this system. The NBPS will combine the aspects of HV pulse (120 kV) and long pulse width (0.5 sec) together to produce a high power system that is unique in the Electrical Engineering field

  7. Radiochemical study of isomerization of free butyl cations

    International Nuclear Information System (INIS)

    Sinotova, E.N.; Nefedov, V.D.; Skorokhodov, S.S.; Arkhipov, Yu.M.

    1987-01-01

    Ion-molecular reactions of free butyl cations, generated by nuclear chemical method, with carbon monoxide containing small quantities of ethanol vapors are studied. Carbon monoxide was used to fix instable butyl cations in the form of corresponding acyl ions. Ester of α-methyl-butyric acid appears to be the only product of free butyl cation interaction with carbon monoxide in the presence of ethanol vapors. That means, that up to the moment of butyl cation reaction with carbon monoxide, the primary butyl cations are almost completely isomerized into secondary in agreement with results of previous investigations. This allows one to study free butyl cation isomerization process according to ion-molecular reaction product isomeric composition

  8. Stability and recovery of DNA origami structure with cation concentration

    Science.gov (United States)

    Chen, Yi; Wang, Ping; Liu, Yang; Liu, Ting; Xu, Yan; Zhu, Shanshan; Zhu, Jun; Ye, Kai; Huang, Guang; Dannong, He

    2018-01-01

    We synthesized triangular and rectangular DNA origami nanostructures and investigated the stability and recovery of them under low cation concentration. Our results demonstrated that the origami nanostructures would melt when incubated in low cation concentration, and recover whilst kept in the concentration for less than 10 min. However, extending the incubation time would lead to irreversible melting. Our results show the possibility of application of DNA origami nanostructures for things such as a sensor for cation concentration response, etc.

  9. Adiabatic differential scanning calorimetric study of divalent cation induced DNA - DPPC liposome formulation compacted for gene delivery

    Directory of Open Access Journals (Sweden)

    Erhan Süleymanoglu

    2004-11-01

    Full Text Available Complexes between nucleic acids and phospholipid vesicles have been developed as stable non-viral gene delivery vehicles. Currently employed approach uses positively charged lipid species and a helper zwitterionic lipid, the latter being applied for the stabilization of the whole complex. However, besides problematic steps during their preparation, cationic lipids are toxic for cells. The present work describes some energetic issues pertinent to preparation and use of neutral lipid-DNA self-assemblies, thus avoiding toxicity of lipoplexes. Differential scanning calorimetry data showed stabilization of polynucleotide helix upon its interaction with liposomes in the presence of divalent metal cations. It is thus possible to suggest this self-assembly as an improved formulation for use in gene delivery.

  10. Modeling Secondary Neutral Helium in the Heliosphere

    International Nuclear Information System (INIS)

    Müller, Hans-Reinhard; Möbius, Eberhard; Wood, Brian E.

    2016-01-01

    An accurate, analytic heliospheric neutral test-particle code for helium atoms from the interstellar medium (ISM) is coupled to global heliospheric models dominated by hydrogen and protons from the solar wind and the ISM. This coupling enables the forward-calculation of secondary helium neutrals from first principles. Secondaries are produced predominantly in the outer heliosheath, upwind of the heliopause, by charge exchange of helium ions with neutral atoms. The forward model integrates the secondary production terms along neutral trajectories and calculates the combined neutral helium phase space density in the innermost heliosphere where it can be related to in-situ observations. The phase space density of the secondary component is lower than that of primary neutral helium, but its presence can change the analysis of primaries and the ISM, and can yield valuable insight into the characteristics of the plasma in the outer heliosheath. (paper)

  11. Molecular clock on a neutral network.

    Science.gov (United States)

    Raval, Alpan

    2007-09-28

    The number of fixed mutations accumulated in an evolving population often displays a variance that is significantly larger than the mean (the overdispersed molecular clock). By examining a generic evolutionary process on a neutral network of high-fitness genotypes, we establish a formalism for computing all cumulants of the full probability distribution of accumulated mutations in terms of graph properties of the neutral network, and use the formalism to prove overdispersion of the molecular clock. We further show that significant overdispersion arises naturally in evolution when the neutral network is highly sparse, exhibits large global fluctuations in neutrality, and small local fluctuations in neutrality. The results are also relevant for elucidating aspects of neutral network topology from empirical measurements of the substitution process.

  12. Neutral particle beam alternative concept for ITER

    International Nuclear Information System (INIS)

    Sedgley, D.; Brook, J.; Luzzi, T.; Deutsch, L.

    1989-01-01

    An analysis of an ITER neutral particle beam system is presented. The analysis covers the neutralizer, ion dumps, pumping, and geometric aspects. The US beam concept for ITER consists of three or four clusters of beamlines delivering approximately 80 MW total of 1.6-MeV deuterium to three or four reactor ports. Each cluster has three self-contained beamlines featuring plasma neutralizers and electrostatic ion dumps. In this study, each of the beamlines has two source assemblies with separate gas neutralizers and magnetic ion dumps. Deuterium is injected into the gas neutralizers by a separate system. Saddle-shaped copper coils augment the tokamak poloidal field to turn the charged particles into the ion dumps. The gas flow from the source, neutralizer, and ion dump is pumped by regenerable cryopanels. The effect of the port between the TF coils and the beam injection angle on the plasma footprint was studied

  13. BEAMS3D Neutral Beam Injection Model

    Energy Technology Data Exchange (ETDEWEB)

    Lazerson, Samuel

    2014-04-14

    With the advent of applied 3D fi elds in Tokamaks and modern high performance stellarators, a need has arisen to address non-axisymmetric effects on neutral beam heating and fueling. We report on the development of a fully 3D neutral beam injection (NBI) model, BEAMS3D, which addresses this need by coupling 3D equilibria to a guiding center code capable of modeling neutral and charged particle trajectories across the separatrix and into the plasma core. Ionization, neutralization, charge-exchange, viscous velocity reduction, and pitch angle scattering are modeled with the ADAS atomic physics database [1]. Benchmark calculations are presented to validate the collisionless particle orbits, neutral beam injection model, frictional drag, and pitch angle scattering effects. A calculation of neutral beam heating in the NCSX device is performed, highlighting the capability of the code to handle 3D magnetic fields.

  14. Neutral-beam current drive in tokamaks

    International Nuclear Information System (INIS)

    Devoto, R.S.

    1986-01-01

    The theory of neutral-beam current drive in tokamaks is reviewed. Experiments are discussed where neutral beams have been used to drive current directly and also indirectly through neoclassical effects. Application of the theory to an experimental test reactor is described. It is shown that neutral beams formed from negative ions accelerated to 500 to 700 keV are needed for this device

  15. Neutral-beam current drive in tokamaks

    International Nuclear Information System (INIS)

    Devoto, R.S.

    1987-01-01

    The theory of neutral-beam current drive in tokamaks is reviewed. Experiments are discussed where neutral beams have been used to drive current directly and also indirectly through neoclassical effects. Application of the theory to an experimental test reactor is described. It is shown that neutral beams formed from negative ions accelerated to 500-700 keV are needed for this device

  16. Adsorption of a cationic dye molecule on polystyrene microspheres in colloids: effect of surface charge and composition probed by second harmonic generation.

    Science.gov (United States)

    Eckenrode, Heather M; Jen, Shih-Hui; Han, Jun; Yeh, An-Gong; Dai, Hai-Lung

    2005-03-17

    Nonlinear optical probe, second harmonic generation (SHG), of the adsorption of the dye molecule malachite green (MG), in cationic form at pH polystyrene microspheres in aqueous solution is used to study the effect of surface charge and composition on molecular adsorption. Three types of polystyrene microspheres with different surface composition are investigated: (1) a sulfate terminated, anionic surface, (2) a neutral surface without any functional group termination, and (3) an amine terminated, cationic surface. The cationic dye was found to adsorb at all three surfaces, regardless of surface charge. The adsorption free energies, DeltaG's, measured for the three surfaces are -12.67, -12.39, and -10.46 kcal/mol, respectively, with the trend as expected from the charge interactions. The adsorption density on the anionic surface, where attractive charge-charge interaction dominates, is determined by the surface negative charge density. The adsorption densities on the neutral and cationic surfaces are on the other hand higher, perhaps as a result of a balance between minimizing repulsive charge interaction and maximizing attractive molecule-substrate and intermolecular interactions. The relative strength of the SH intensity per molecule, in combination of a model calculation, reveals that the C(2) axis of the MG molecule is nearly perpendicular to the surface on the anionic surface and tilts away from the surface norm when the surface is neutral and further away when cationic. Changing the pH of the solution may alter the surface charge and subsequently affect the adsorption configuration and SH intensity.

  17. Synthesis of some (eta-arene)dihydridorhenium cations and their reactions with LiAlH/sub 4/ and LiAlD/sub 4/

    Energy Technology Data Exchange (ETDEWEB)

    Baudrey, D.; Boydell, P.; Ephritikhine, M.

    1986-03-01

    A series of cations (Re(eta-arene)H/sub 2/(PPh/sub 3/)/sub 2/)/sup +/ (arene benzene, toluene, p-xylene, or mesitylene) was prepared from the corresponding neutral dihydridocyclohexadienyl complexes by treatment with CPh/sub 3/BF/sub 4/. These cations reacted with LiAlH/sub 4/ and LiAlD/sub 4/ to form dihydridocyclohexadienyl complexes. The unusual selectivity of the hydride attack is explained by steric interactions between the ring methyl groups and the bulky phosphine ligands. The initial product of the reaction of the eta-mesitylene cation with LiAlD/sub 4/ allows the isomerisation mechanism for the cyclohexadienyl complexes to be clarified.

  18. On implicit abstract neutral nonlinear differential equations

    Energy Technology Data Exchange (ETDEWEB)

    Hernández, Eduardo, E-mail: lalohm@ffclrp.usp.br [Universidade de São Paulo, Departamento de Computação e Matemática, Faculdade de Filosofia Ciências e Letras de Ribeirão Preto (Brazil); O’Regan, Donal, E-mail: donal.oregan@nuigalway.ie [National University of Ireland, School of Mathematics, Statistics and Applied Mathematics (Ireland)

    2016-04-15

    In this paper we continue our developments in Hernández and O’Regan (J Funct Anal 261:3457–3481, 2011) on the existence of solutions for abstract neutral differential equations. In particular we extend the results in Hernández and O’Regan (J Funct Anal 261:3457–3481, 2011) for the case of implicit nonlinear neutral equations and we focus on applications to partial “nonlinear” neutral differential equations. Some applications involving partial neutral differential equations are presented.

  19. Structural Basis for Differential Neutralization of Ebolaviruses

    Directory of Open Access Journals (Sweden)

    John M. Dye

    2012-04-01

    Full Text Available There are five antigenically distinct ebolaviruses that cause hemorrhagic fever in humans or non-human primates (Ebola virus, Sudan virus, Reston virus, Taï Forest virus, and Bundibugyo virus. The small handful of antibodies known to neutralize the ebolaviruses bind to the surface glycoprotein termed GP1,2. Curiously, some antibodies against them are known to neutralize in vitro but not protect in vivo, whereas other antibodies are known to protect animal models in vivo, but not neutralize in vitro. A detailed understanding of what constitutes a neutralizing and/or protective antibody response is critical for development of novel therapeutic strategies. Here, we show that paradoxically, a lower affinity antibody with restricted access to its epitope confers better neutralization than a higher affinity antibody against a similar epitope, suggesting that either subtle differences in epitope, or different characteristics of the GP1,2 molecules themselves, confer differential neutralization susceptibility. Here, we also report the crystal structure of trimeric, prefusion GP1,2 from the original 1976 Boniface variant of Sudan virus complexed with 16F6, the first antibody known to neutralize Sudan virus, and compare the structure to that of Sudan virus, variant Gulu. We discuss new structural details of the GP1-GP2 clamp, thermal motion of various regions in GP1,2 across the two viruses visualized, details of differential interaction of the crystallized neutralizing antibodies, and their relevance for virus neutralization.

  20. Cation depletion by the sodium pump in red cells with pathologic cation leaks. Sickle cells and xerocytes.

    OpenAIRE

    Joiner, C H; Platt, O S; Lux, S E

    1986-01-01

    The mechanism by which sickle cells and xerocytic red cells become depleted of cations in vivo has not been identified previously. Both types of cells exhibit elevated permeabilities to sodium and potassium, in the case of sickle cells, when deoxygenated. The ouabain-insensitive fluxes of sodium and potassium were equivalent, however, in both cell types under these conditions. When incubated 18 hours in vitro, sickle cells lost cations but only when deoxygenated. This cation depletion was blo...

  1. Liberal Neutrality : Constructivist, not foundationalist

    Directory of Open Access Journals (Sweden)

    Lendell Horne

    2009-06-01

    Full Text Available In defending the principle of neutrality, liberals have often appealed to a more general moral principle that forbids coercing persons in the name of reasons those persons themselves cannot reasonably be expected to share. Yet liberals have struggled to articulate a non-arbitrary, non-dogmatic distinction between the reasons that persons can reasonably be expected to share and those they cannot. The reason for this, I argue, is that what it means to “share a reason” is itself obscure. In this paper I articulate two different conceptions of what it is to share a reason; I call these conceptions “foundationalist” and “constructivist.” On the foundationalist view, two people “share” a reason just in the sense that the same reason applies to each of them independently. On this view, I argue, debates about the reasons we share collapse into debates about the reasons we have, moving us no closer to an adequate defense of neutrality. On the constructivist view, by contrast, “sharing reasons” is understood as a kind of activity, and the reasons we must share are just those reasons that make this activity possible. I argue that the constructivist conception of sharing reasons yields a better defense of the principle of neutrality. À travers leur défense du principe de neutralité, les libéraux ont souvent interpellé un principe moral plus général qui interdit de contraindre des personnes pour des raisons dont on ne peut raisonnablement attendre que ces personnes elles-mêmes les partagent. Les libéraux éprouvent cependant de la difficulté à articuler une distinction non-arbitraire et non-dogmatique entre les raisons dont on peut raisonnablement attendre que les personnes les partagent et celles dont on ne le peut pas. Je soutiens dans cet article que cette difficulté provient du fait que «partager une raison » est une notion obscure. Pour illustrer cela, je me pencherai sur deux conceptions distinctes de ce que veut dire

  2. Chemical acceleration of a neutral granulated blast-furnace slag activated by sodium carbonate

    International Nuclear Information System (INIS)

    Kovtun, Maxim; Kearsley, Elsabe P.; Shekhovtsova, Julia

    2015-01-01

    This paper presents results of a study on chemical acceleration of a neutral granulated blast-furnace slag activated using sodium carbonate. As strength development of alkali-activated slag cements containing neutral GBFS and sodium carbonate as activator at room temperature is known to be slow, three accelerators were investigated: sodium hydroxide, ordinary Portland cement and a combination of silica fume and slaked lime. In all cements, the main hydration product is C–(A)–S–H, but its structure varies between tobermorite and riversideite depending on the accelerator used. Calcite and gaylussite are present in all systems and they were formed due to either cation exchange reaction between the slag and the activator, or carbonation. With accelerators, compressive strength up to 15 MPa can be achieved within 24 h in comparison to 2.5 MPa after 48 h for a mix without an accelerator

  3. Investigation of electron exchange between neutral and ionized centers of germanium in PbSe

    International Nuclear Information System (INIS)

    Terukov, I.E.; Khuzhakulov, Eh.S.

    2005-01-01

    The 73 As( 73 Ge) emission Moessbauer spectroscopy is applied to study the electron exchange between neutral ionized states of the germanium donor center in PbSe. It is shown that the charge state of the antistructural 73 Ge defect, generating in the anion PbSe sublattice after 73 As radioactive decay, does not depend on the Fermi level location. In contrast to this, the 73 Ge center in the cation PbSe sublattice is the isoelectronic substitution impurity. The analysis of emission Moessbauer spectra of p-type PbSe: 73 As testifies about the presence of the fast electron exchange between neutral and ionized donor Ge centers in PbSe [ru

  4. Gas-phase reactivity of lanthanide cations with fluorocarbons: C-F versus C-H and C-C bond activation

    International Nuclear Information System (INIS)

    Cornehl, H.H.; Hornung, G.; Schwarz, H.

    1996-01-01

    The gas-phase reactivity of the fluorinated hydrocarbons CF 4 , CHF 3 , CH 3 F, C 2 F 6 , 1,1-C 2 H 4 F 2 , and C 6 F 6 with the lanthanide cations Ce + , Pr + , Sm + , Ho + , Tm + , and Yb + and the reactivity of C 6 H 5 F with all lanthanide cations Ln + (Ln = La-Lu, with the exception of Pm + ) have been examined by Fourier-transform ion cyclotron resonance mass spectrometry. The perfluorinated compounds tetrafluoromethane and hexafluoroethane as well as trifluoromethane do not react with any lanthanide cation. Selective activation of the strong C-F bonds in fluoromethane, 1,1-difluoroethane, hexafluorobenzene, and fluorobenzene appears as a general reaction scheme along the 4f row. Experimental evidence is given for a 'harpoon'-like mechanism for the F atom abstraction process which operates via an initial electron transfer from the lanthanide cation to the fluorinated substrate in the encounter complex Ln + RF. The most reactive lanthanides La + , Ce + , Gd + , and Tb + and also the formal closed-shell species Lu + exhibit additional C-H and C-C bond activation pathways in the reaction with fluorobenzene, namely dehydrohalogenation as well as loss of a neutral acetylene molecule. In the case of Tm + and Yb + the formation of neutral LnF 3 is observed in a multistep process via C-C coupling and charge transfer. 17 refs., 2 figs., 2 tabs

  5. Predicting Organic Cation Sorption Coefficients: Accounting for Competition from Sorbed Inorganic Cations Using a Simple Probe Molecule.

    Science.gov (United States)

    Jolin, William C; Goyetche, Reaha; Carter, Katherine; Medina, John; Vasudevan, Dharni; MacKay, Allison A

    2017-06-06

    With the increasing number of emerging contaminants that are cationic at environmentally relevant pH values, there is a need for robust predictive models of organic cation sorption coefficients (K d ). Current predictive models fail to account for the differences in the identity, abundance, and affinity of surface-associated inorganic exchange ions naturally present at negatively charged receptor sites on environmental solids. To better understand how organic cation sorption is influenced by surface-associated inorganic exchange ions, sorption coefficients of 10 organic cations (including eight pharmaceuticals and two simple probe organic amines) were determined for six homoionic forms of the aluminosilicate mineral, montmorillonite. Organic cation sorption coefficients exhibited consistent trends for all compounds across the various homoionic clays with sorption coefficients (K d ) decreasing as follows: K d Na + > K d NH 4 + ≥ K d K + > K d Ca 2+ ≥ K d Mg 2+ > K d Al 3+ . This trend for competition between organic cations and exchangeable inorganic cations is consistent with the inorganic cation selectivity sequence, determined for exchange between inorganic ions. Such consistent trends in competition between organic and inorganic cations suggested that a simple probe cation, such as phenyltrimethylammonium or benzylamine, could capture soil-to-soil variations in native inorganic cation identity and abundance for the prediction of organic cation sorption to soils and soil minerals. Indeed, sorption of two pharmaceutical compounds to 30 soils was better described by phenyltrimethylammonium sorption than by measures of benzylamine sorption, effective cation exchange capacity alone, or a model from the literature (Droge, S., and Goss, K. Environ. Sci. Technol. 2013, 47, 14224). A hybrid approach integrating structural scaling factors derived from this literature model of organic cation sorption, along with phenyltrimethylammonium K d values, allowed for

  6. Computational study of cation substitutions in apatites

    International Nuclear Information System (INIS)

    Tamm, Toomas; Peld, Merike

    2006-01-01

    Density-functional theory plane-wave modeling of fluor- and hydroxyapatites has been performed, where one or two calcium ions per unit cell were replaced with cadmium or zinc cations. It was found that cadmium ions favor Ca(1) positions in fluorapatites and Ca(2) positions in hydroxyapatites, in agreement with experiment. A similar pattern is predicted for zinc substitutions. In the doubly substituted cases, where only hydroxyapatites were modeled, a preference for the substituting ions to be located in Ca(2) position was also observed. Displacement of the hydroxide ions from their symmetrical positions on the hexagonal axis can be used to explain the preferred configurations of substituting ions around the axis. -- Deformation of the hydroxide ion chain due to substitutions around the ion channel in substituted hydroxyapatites

  7. Retention of Cationic Starch onto Cellulose Fibres

    Science.gov (United States)

    Missaoui, Mohamed; Mauret, Evelyne; Belgacem, Mohamed Naceur

    2008-08-01

    Three methods of cationic starch titration were used to quantify its retention on cellulose fibres, namely: (i) the complexation of CS with iodine and measurement of the absorbency of the ensuing blue solution by UV-vis spectroscopy; (ii) hydrolysis of the starch macromolecules followed by the conversion of the resulting sugars to furan-based molecules and quantifying the ensuing mixture by measuring their absorbance at a Ι of 490 nm, using the same technique as previous one and; finally (iii) hydrolysis of starch macromolecules by trifluoro-acetic acid and quantification of the sugars in the resulting hydrolysates by high performance liquid chromatography. The three methods were found to give similar results within the range of CS addition from 0 to 50 mg per g of cellulose fibres.

  8. Repurposing Cationic Amphiphilic Antihistamines for Cancer Treatment

    DEFF Research Database (Denmark)

    Ellegaard, Anne-Marie; Dehlendorff, Christian; Vind, Anna C.

    2016-01-01

    Non-small cell lung cancer (NSCLC) is one of the deadliest cancers worldwide. In search for new NSCLC treatment options, we screened a cationic amphiphilic drug (CAD) library for cytotoxicity against NSCLC cells and identified several CAD antihistamines as inducers of lysosomal cell death. We...... then performed a cohort study on the effect of CAD antihistamine use on mortality of patients diagnosed with non-localized cancer in Denmark between 1995 and 2011. The use of the most commonly prescribed CAD antihistamine, loratadine, was associated with significantly reduced all-cause mortality among patients...... with non-localized NSCLC or any non-localized cancer when compared with use of non-CAD antihistamines and adjusted for potential confounders. Of the less frequently described CAD antihistamines, astemizole showed a similar significant association with reduced mortality as loratadine among patients with any...

  9. Use of a material conducting hydrogen cations

    International Nuclear Information System (INIS)

    Howe, A.T.; Shilton, M.G.

    1986-01-01

    The invention concerns a separator conducting hydrogenous for electrical devices, which contains at least one compound with the formula H(UO 2 )PO 4 x nH 2 O, H(UO 2 )AsO 4 x nH 2 O or H(UO 2 )IO 4 (OH) 2 x nH 2 O, where not more than 50% by weight of the H + is replaced by one or more cations, such as Li + , Na + , K + , NH 4 + , Cu 2+ , Mg 2+ , Ca 2+ , Ba 2+ , Sr 2+ , Pb 2+ , Fe 2+ , Co 2+ , Ni 2+ , Mn 2+ or Al 3+ . The electrical device having the separator can be an electrolysis cell, for example, an electro chromium cell. (H x WO 3 ), a hydrogen isotope enrichment device, a proton-sensitive electrode (eg for a pH meter), a battery or a fuel cell. (orig./MM) [de

  10. A Cationic Smart Copolymer for DNA Binding

    Directory of Open Access Journals (Sweden)

    Tânia Ribeiro

    2017-11-01

    Full Text Available A new block copolymer with a temperature-responsive block and a cationic block was prepared by reversible addition-fragmentation chain transfer (RAFT polymerization, with good control of its size and composition. The first block is composed by di(ethylene glycol methyl ether methacrylate (DEGMA and oligo(ethylene glycol methyl ether methacrylate (OEGMA, with the ratio DEGMA/OEGMA being used to choose the volume phase transition temperature of the polymer in water, tunable from ca. 25 to above 90 °C. The second block, of trimethyl-2-methacroyloxyethylammonium chloride (TMEC, is positively charged at physiological pH values and is used for DNA binding. The coacervate complexes between the block copolymer and a model single strand DNA are characterized by fluorescence correlation spectroscopy and fluorescence spectroscopy. The new materials offer good prospects for biomedical application, for example in controlled gene delivery.

  11. Hydration Structure of the Quaternary Ammonium Cations

    KAUST Repository

    Babiaczyk, Wojtek Iwo

    2010-11-25

    Two indicators of the hydropathicity of small solutes are introduced and tested by molecular dynamics simulations. These indicators are defined as probabilities of the orientation of water molecules\\' dipoles and hydrogen bond vectors, conditional on a generalized distance from the solute suitable for arbitrarily shaped molecules. Using conditional probabilities, it is possible to distinguish features of the distributions in close proximity of the solute. These regions contain the most significant information on the hydration structure but cannot be adequately represented by using, as is usually done, joint distance-angle probability densities. Our calculations show that using our indicators a relative hydropathicity scale for the interesting test set of the quaternary ammonium cations can be roughly determined. © 2010 American Chemical Society.

  12. Calixarenes synthesized for seducing and trapping cations

    International Nuclear Information System (INIS)

    Dozol, J.F.

    1997-01-01

    Calixarenes are known to be selective extractants for cesium radioactive cations. This liquid-liquid extraction is still to be studied and would allow to reduce the volume of years living radioactive wastes before they were stored and perhaps to remove then the cesium by transmutation. Calixarenes are macrocycles with phenolic units bridged by methylene groups. They have the important property to have a flexible structure. On this basic structure, all kinds of chemical functions can be branched. They thus confer particular properties to the molecule. A computerized virtual construction phase of molecules is actually studied in order to optimize the extraction. It is currently known that with small modifications it will be possible to selectively extract heavy metals (Hg, Cd..) coming from industrial pollution. (O.M.)

  13. Safety evaluation of cation-exchange resins

    International Nuclear Information System (INIS)

    Kalkwarf, D.R.

    1977-08-01

    Results are presented of a study to evaluate whether sufficient information is available to establish conservative limits for the safe use of cation-exchange resins in separating radionuclides and, if not, to recommend what new data should be acquired. The study was also an attempt to identify in-line analytical techniques for the evaluation of resin degradation during radionuclide processing. The report is based upon a review of the published literature and upon discussions with many people engaged in the use of these resins. It was concluded that the chief hazard in the use of cation-exchange resins for separating radionuclides is a thermal explosion if nitric acid or other strong oxidants are present in the process solution. Thermal explosions can be avoided by limiting process parameters so that the rates of heat and gas generation in the system do not exceed the rates for their transfer to the surroundings. Such parameters include temperature, oxidant concentration, the amounts of possible catalysts, the radiation dose absorbed by the resin and the diameter of the resin column. Current information is not sufficient to define safe upper limits for these parameters. They can be evaluated, however, from equations derived from the Frank-Kamenetskii theory of thermal explosions provided the heat capacities, thermal conductivities and rates of heat evolution in the relevant resin-oxidant mixtures are known. It is recommended that such measurements be made and the appropriate limits be evaluated. A list of additional safety precautions are also presented to aid in the application of these limits and to provide additional margins of safety. In-line evaluation of resin degradation to assess its safety hazard is considered impractical. Rather, it is recommended that the resin be removed from use before it has received the limiting radiation dose, evaluated as described above

  14. Anaerobic toxicity of cationic silver nanoparticles

    International Nuclear Information System (INIS)

    Gitipour, Alireza; Thiel, Stephen W.; Scheckel, Kirk G.; Tolaymat, Thabet

    2016-01-01

    The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag"+ under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged polyvinylpyrrolidone coated AgNPs (PVP-AgNPs) and (3) positively charged branched polyethyleneimine coated AgNPs (BPEI-AgNPs). The AgNPs investigated in this experiment were similar in size (10–15 nm), spherical in shape, but varied in surface charge which ranged from highly negative to highly positive. While, at AgNPs concentrations lower than 5 mg L"−"1, the anaerobic decomposition process was not influenced by the presence of the nanoparticles, there was an observed impact on the diversity of the microbial community. At elevated concentrations (100 mg L"−"1 as silver), only the cationic BPEI-AgNPs demonstrated toxicity similar in magnitude to that of Ag"+. Both citrate and PVP-AgNPs did not exhibit toxicity at the 100 mg L"−"1 as measured by biogas evolution. These findings further indicate the varying modes of action for nanoparticle toxicity and represent one of the few studies that evaluate end-of-life management concerns with regards to the increasing use of nanomaterials in our everyday life. These findings also highlight some of the concerns with a one size fits all approach to the evaluation of environmental health and safety concerns associated with the use of nanoparticles. - Highlights: • At concentrations -1 the anaerobic decomposition process was not impacted. • An impact on the microbial community at concentrations -1 were observed. • At high concentrations (100 mg L"−"1), the cationic BPEI-AgNPs demonstrated toxicity. • Toxicity was demonstrated without the presence of oxidative dissolution of silver. • A one size fits all approach for the evaluation of NPs may not be accurate.

  15. Increased localized delivery of piroxicam by cationic nanoparticles after intra-articular injection

    Directory of Open Access Journals (Sweden)

    Kim SR

    2016-11-01

    Full Text Available Sung Rae Kim,1 Myoung Jin Ho,2 Sang Hyun Kim,1 Ha Ra Cho,2 Han Sol Kim,2 Yong Seok Choi,2 Young Wook Choi,1 Myung Joo Kang2 1Division of Pharmaceutical Sciences, College of Pharmacy, Chung-Ang University, Seoul, 2College of Pharmacy, Dankook University, Cheonan, Chungnam, South Korea Abstract: Piroxicam (PRX, a potent nonsteroidal anti-inflammatory drug, is prescribed to relieve postoperative and/or chronic joint pain. However, its oral administration often results in serious gastrointestinal adverse effects including duodenal ulceration. Thus, a novel cationic nanoparticle (NP was explored to minimize the systemic exposure and increase the retention time of PRX in the joint after intra-articular (IA injection, by forming micrometer-sized electrostatic clusters with endogenous hyaluronic acid (HA in the synovial cavity. PRX-loaded NPs consisting of poly(lactic-co-glycolic acid, Eudragit RL, and polyvinyl alcohol were constructed with the following characteristics: particle size of 220 nm, zeta potential of 11.5 mV in phosphate-buffered saline, and loading amount of 4.0% (w/w of PRX. In optical and hyperspectral observations, the cationic NPs formed more than 50 µm-sized aggregates with HA, which was larger than the intercellular gaps between synoviocytes. In an in vivo pharmacokinetic study in rats, area under the plasma concentration–time curve (AUC0–24 h and maximum plasma concentration (Cmax of PRX after IA injection of the cationic NPs were <70% (P<0.05 and 60% (P<0.05, respectively, compared to those obtained from drug solution. Moreover, the drug concentration in joint tissue 24 h after dosing with the cationic NPs was 3.2-fold (P<0.05 and 1.8-fold (P<0.05 higher than that from drug solution and neutrally charged NPs, respectively. Therefore, we recommend the IA cationic NP therapy as an effective alternative to traditional oral therapy with PRX, as it increases drug retention selectively in the joint. Keywords: piroxicam

  16. Spectroscopy of electronic transitions in Polycyclic Aromatic Hydrocarbon cations and their clusters

    International Nuclear Information System (INIS)

    Friha, Hela

    2012-01-01

    excited states of the homogeneous dimer cations cited above. In complement to these experimental achievements, a theoretical study has been made in the context of the main astrophysical signatures of PAHs, the series of mid-infrared emission bands known as the Aromatic Infrared Bands for AIBs. These spectra are discussed and interpreted in the light of earlier works. This study consisted in calculations of structures and infrared spectra of neutral and cationic dehydrogenated naphthalene derivatives using the Density Functional method. The vibrational data derived from DFT calculations were then used by the welcoming team as input for numerical simulations, using a kinetic Monte Carlo procedure, which allowed the determination of the infrared emission spectrum expected from the heating of the naphthalene molecule by 6.4 eV. (author) [fr

  17. Modelling of marine base cation emissions, concentrations and deposition in the UK

    Directory of Open Access Journals (Sweden)

    M. Werner

    2011-02-01

    Full Text Available Base cations exert a large impact on various geochemical and geophysical processes both in the atmosphere and at the Earth surface. One of the essential roles of these compounds is impact on surface pH causing an increase in alkalinity and neutralizing the effects of acidity generated by sulphur and nitrogen deposition. During recent years anthropogenic emissions of base cations in the UK have decreased substantially, by about 70%, 78%, 75% and 48% for Na+, Mg2+, Ca2+ and K+, respectively, over the period 1990–2006. For the island regions, such as the UK, the main source of base cation particles is the aerosol produced from the sea surface. Here, the sea salt aerosol (SSA emissions are calculated with parameterisations proposed by Mårtensson et al. (2003 for ultra fine particles, Monahan et al. (1986 for fine particles and Smith and Harisson (1998 for coarse particles continuously with a 0.1 μm size step using WRF-modelled wind speed data at a 5 km × 5 km grid square resolution with a 3 h time step for two selected years 2003 and 2006. SSA production has been converted into base cation emissions, with the assumption that the chemical composition of the particle emitted from the sea surface is equal to the chemical composition of sea water, and used as input data in the Fine Resolution Atmospheric Multi-pollutant Exchange Model (FRAME. FRAME model annual mean concentrations and total wet deposition at a 5 km × 5 km grid resolution, are compared with concentrations in air and wet deposition from the National Monitoring Network and measurements based estimates of UK deposition budget. The correlation coefficient for wet deposition achieves high values (R = 0.8 for Na+ and Mg2+, whereas for Ca2+ the correlation is poor (R < 0.3. Base cation concentrations are also represented well, with some overestimations on the west coast and underestimations in the

  18. The status of neutral currents

    International Nuclear Information System (INIS)

    Zwirner, F.

    1987-11-01

    The situation of particle physics today is quite puzzling. On the one hand, the Standard Model (SM) of strong and electroweak interactions is consistent with all confirmed experimental data but theoretically rather unsatisfactory. On the other hand, none of the many theoretical speculations which try to go beyond the SM has (yet) received the slightest experimental support. The solution to this dilemma can only come from new data: either from the detection of a new particle threshold at high energy colliders, or from the appearance of some small discrepancy in high-precision experiments. A crucial sector for testing the SM and its extensions is that of neutral currents (NC), where an impressive amount of data has been collected in recent years. While waiting for the next generation of experiments, it is certainly useful to take stock of our knowledge, determining the NC parameters as precisely as we can and putting limits on possible deviations from the SM. The present talk contains the results of a recent analysis along these lines: the first part illustrates how a set of 'model-independent' parameters can be extracted from the available NC data, the second part particularizes the analysis to the SM and to some superstring-inspired models with an additional Z' in their low-energy spectrum. 27 refs., 3 figs., 1 tab

  19. Organic cation rhodamines for screening organic cation transporters in early stages of drug development.

    Science.gov (United States)

    Ugwu, Malachy C; Oli, Angus; Esimone, Charles O; Agu, Remigius U

    The aim of this study was to investigate the suitability of rhodamine-123, rhodamine-6G and rhodamine B as non-radioactive probes for characterizing organic cation transporters in respiratory cells. Fluorescent characteristics of the compounds were validated under standard in vitro drug transport conditions (buffers, pH, and light). Uptake/transport kinetics and intracellular accumulation of the compounds were investigated. Uptake/transport mechanisms were investigated by comparing the effect of pH, temperature, concentration, polarity, OCTs/OCTNs inhibitors/substrates, and metabolic inhibitors on the cationic dyes uptake in Calu-3 cells. Fluorescence stability and intensity of the compounds were altered by buffer composition, light, and pH. Uptake of the dyes was concentration-, temperature- and pH-dependent. OCTs/OCTNs inhibitors significantly reduced intracellular accumulation of the compounds. Whereas rhodamine-B uptake was sodium-dependent, pH had no effect on rhodamine-123 and rhodamine-6G uptake. Transport of the dyes across the cells was polarized: (AP→BL>BL→AP transport) and saturable: {V max =14.08±2.074, K m =1821±380.4 (rhodamine-B); V max =6.555±0.4106, K m =1353±130.4 (rhodamine-123) and V max =0.3056±0.01402, K m =702.9±60.97 (rhodamine-6G)}. The dyes were co-localized with MitoTracker®, the mitochondrial marker. Cationic rhodamines, especially rhodamine-B and rhodamine- 6G can be used as organic cation transporter substrates in respiratory cells. During such studies, buffer selection, pH and light exposure should be taken into consideration. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. Auditors' Professional Skepticism: Neutrality versus Presumptive Doubt

    NARCIS (Netherlands)

    Groot, T.L.C.M.; Quadackers, L.M.; Wright, A.

    2014-01-01

    Although skepticism is widely viewed as essential to audit quality, there is a debate about what form is optimal. The two prevailing perspectives that have surfaced are "neutrality" and "presumptive doubt." With neutrality, auditors neither believe nor disbelieve client management. With presumptive

  1. 32 CFR 644.323 - Neutral language.

    Science.gov (United States)

    2010-07-01

    ... 32 National Defense 4 2010-07-01 2010-07-01 true Neutral language. 644.323 Section 644.323 National Defense Department of Defense (Continued) DEPARTMENT OF THE ARMY (CONTINUED) REAL PROPERTY REAL ESTATE HANDBOOK Disposal § 644.323 Neutral language. Wherever the words “man”, “men”, or their related...

  2. 3He neutral current detectors at SNO

    International Nuclear Information System (INIS)

    Elliott, S.R.; Browne, M.C.; Doe, P.J.

    1998-01-01

    The flux of solar neutrinos measured via charged and neutral current interactions can provide a model independent test of neutrino oscillations. Since the Sudbury Neutrino Observatory uses heavy water as a target, it has a large sensitivity to both interactions. A technique for observing the neutral current breakup of the deuteron using 3 He proportional counters is described

  3. Photoproduction of neutral pions off protons

    NARCIS (Netherlands)

    Crede, V.; Sparks, N.; Wilson, A.; Anisovich, A. V.; Bacelar, J. C. S.; Bantes, R.; Bartholomy, O.; Bayadilov, D.; Beck, R.; Beloglazov, Y. A.; Castelijns, R.; Dutz, H.; Elsner, D.; Ewald, R.; Frommberger, F.; Funke, Chr; Gregor, R.; Gridnev, A.; Gutz, E.; Hillert, W.; Hoffmeister, P.; Jaegle, I.; Junkersfeld, J.; Kalinowsky, H.; Kammer, S.; Klein, Frank; Klein, Friedrich; Klempt, E.; Kotulla, M.; Krusche, B.; Löhner, H.; Lopatin, I. V.; Lugert, S.; Menze, D.; Mertens, T.; Messchendorp, J. G.; Metag, V.; Nanova, M.; Nikonov, V. A.; Novinski, D.; Novotny, R.; Ostrick, M.; Pant, L. M.; van Pee, H.; Pfeiffer, M.; Roy, A.; Sarantsev, A. V.; Schadmand, S.; Schmidt, C.; Schmieden, H.; Schoch, B.; Shende, S.; Sokhoyan, V.; Suele, A.; Sumachev, V. V.; Szczepanek, T.; Thoma, U.; Trnka, D.; Varma, R.; Walther, D.; Wendel, Ch

    2011-01-01

    Photoproduction of neutral pions has been studied with the CBELSA/TAPS detector in the reaction gamma p -> p pi(0) for photon energies between 0.85 and 2.50 GeV. The pi(0) mesons are observed in their dominant neutral decay mode: pi(0) -> gamma gamma. For the first time, the differential cross

  4. On the possible eigenoscillations of neutral sheets

    International Nuclear Information System (INIS)

    Almeida, W.A.; Costa, J.M. da; Aruquipa, E.G.; Sudano, J.P.

    1974-12-01

    A neutral sheet model with hyperbolic tangent equilibrium magnetic field and hyperbolic square secant density profiles is considered. It is shown that the equation for small oscillations takes the form of an eigenvalue oscillation problem. Computed eigenfrequencies of the geomagnetic neutral sheet were found to be in the range of the resonant frequencies of the geomagnetic plasma sheet computed by other authors

  5. Gender Neutrality: Women's Friend or Foe?

    Science.gov (United States)

    Steuernagel, Trudy

    Gender neutral public policies are those that are either silent on the question of the existence of significant gender differences or incorporate a perspective which mandates that such differences be ignored. Prominent voices today contend that gender neutrality favors males and have held the male standard as the one for which women should aspire.…

  6. Targets for high power neutral beams

    International Nuclear Information System (INIS)

    Kim, J.

    1980-01-01

    Stopping high-power, long-pulse beams is fast becoming an engineering challenge, particularly in neutral beam injectors for heating magnetically confined plasmas. A brief review of neutral beam target technology is presented along with heat transfer calculations for some selected target designs

  7. On plasma-neutral gas interaction

    International Nuclear Information System (INIS)

    Venkataramani, N.; Mattoo, S.K.

    1980-01-01

    The importance of plasma-neutral gas interaction layer has been emphasized by pointing out its application to a wide variety of physical phenomena. The interaction of a magnetised plasma stream penetrating a neutral gas cloud is discussed in the light of Alfven's critical velocity and Varma's threshold velocity on the ionising interaction. Interaction of a moving magnetised plasma with a stationary neutral gas has been studied and described. The device comprises of a plasma gun and an interaction region where neutral gas cloud is injected. The interaction region is provided with a transverse magnetic field of upto 1000 G. Several diagnostics deployed at the interaction region to make measurements on the macroscopic parameters of plasma and neutral gas are described. The parameters of discharge circuits are measured with high current and voltage probes. An interaction between a magnetised plasma stream and a neutral gas cloud is demonstrated. It is shown that this interaction does not have Varma's threshold on their relative velocity. The Alfven's critical velocity phenomenon is shown to depend on the integrated column neutral gas density that a plasma stream encounters while penetrating through it and not on the neutral gas density in the range of 10 17 -10 21 m -3 . (auth.)

  8. Net Neutrality and Inflation of Traffic

    NARCIS (Netherlands)

    Peitz, M.; Schütt, F.

    2015-01-01

    Under strict net neutrality Internet service providers (ISPs) are required to carry data without any differentiation and at no cost to the content provider. We provide a simple framework with a monopoly ISP to evaluate different net neutrality rules. Content differs in its sensitivity to delay.

  9. Net neutrality and inflation of traffic

    NARCIS (Netherlands)

    Peitz, M.; Schütt, Florian

    Under strict net neutrality Internet service providers (ISPs) are required to carry data without any differentiation and at no cost to the content provider. We provide a simple framework with a monopoly ISP to evaluate the short-run effects of different net neutrality rules. Content differs in its

  10. Neutralization of wastewater from nitrite passivation

    International Nuclear Information System (INIS)

    Pawlowski, L.; Mientki, B.; Wasag, H.

    1982-01-01

    A method for neutralization of wastewater formed in nitrite passivation has been presented. The method consists of introducing urea into wastewater and acidifying it with sulphuric acid. Wastewater is neutralized with lime. After clarification, wastewater can be drained outside the plant

  11. A neutral sampling formula for multiple samples and an `exact' test of neutrality

    NARCIS (Netherlands)

    Etienne, R.S.

    2007-01-01

    As the utility of the neutral theory of biodiversity is increasingly being recognized, there is also an increasing need for proper tools to evaluate the relative importance of neutral processes (dispersal limitation and stochasticity). One of the key features of neutral theory is its close link to

  12. A neutral sampling formula for multiple samples and an 'exact' test of neutrality

    NARCIS (Netherlands)

    Etienne, Rampal S.

    As the utility of the neutral theory of biodiversity is increasingly being recognized, there is also an increasing need for proper tools to evaluate the relative importance of neutral processes (dispersal limitation and stochasticity). One of the key features of neutral theory is its close link to

  13. Stable polyfluorinated cycloalkenyl cations and their NMR spectra

    International Nuclear Information System (INIS)

    Snegirev, V.F.; Galakhov, M.V.; Makarov, K.N.; Bakhmutov, V.I.

    1986-01-01

    New stable 1-methoxyperfluoro-2-ethylcyclobutenyl, 1-methoxyperfluoro-2-methylcyclo-pentenyl, and 1-methoxyperfluoro-2-ethylcyclohexenyl cations were obtained by the action of antimony pentafluoride on the corresponding olefins. The distribution of the charges in the investigated polyfluorinated cycloalkenyl cations was investigated by 13 C NMR method

  14. Synthesis of Cationic Core-Shell Latex Particles

    NARCIS (Netherlands)

    Dziomkina, N.; Hempenius, Mark A.; Vancso, Gyula J.

    2006-01-01

    Surfactant-free seeded (core-shell) polymerization of cationic polymer colloids is presented. Polystyrene core particles with sizes between 200 nm and 500 nm were synthesized. The number average diameter of the colloidal core particles increased with increasing monomer concentration. Cationic shells

  15. Cationic antimicrobial peptides inactivate Shiga toxin-encoding bacteriophages

    Science.gov (United States)

    Del Cogliano, Manuel E.; Hollmann, Axel; Martinez, Melina; Semorile, Liliana; Ghiringhelli, Pablo D.; Maffía, Paulo C.; Bentancor, Leticia V.

    2017-12-01

    Shiga toxin (Stx) is the principal virulence factor during Shiga toxin-producing Escherichia coli (STEC) infections. We have previously reported the inactivation of bacteriophage encoding Stx after treatment with chitosan, a linear polysaccharide polymer with cationic properties. Cationic antimicrobial peptides (cAMPs) are short linear aminoacidic sequences, with a positive net charge, which display bactericidal or bacteriostatic activity against a wide range of bacterial species. They are promising novel antibiotics since they have shown bactericidal effects against multiresistant bacteria. To evaluate whether cationic properties are responsible for bacteriophage inactivation, we tested seven cationic peptides with proven antimicrobial activity as anti-bacteriophage agents, and one random sequence cationic peptide with no antimicrobial activity as a control. We observed bacteriophage inactivation after incubation with five cAMPs, but no inactivating activity was observed with the random sequence cationic peptide or with the non alpha helical cAMP Omiganan. Finally, to confirm peptide-bacteriophage interaction, zeta potential was analyzed by following changes on bacteriophage surface charges after peptide incubation. According to our results we could propose that: 1) direct interaction of peptides with phage is a necessary step for bacteriophage inactivation, 2) cationic properties are necessary but not sufficient for bacteriophage inactivation, and 3) inactivation by cationic peptides could be sequence (or structure) specific. Overall our data suggest that these peptides could be considered a new family of molecules potentially useful to decrease bacteriophage replication and Stx expression.

  16. CATION EXCHANGE METHOD FOR THE RECOVERY OF PROTACTINIUM

    Science.gov (United States)

    Studier, M.H.; Sullivan, J.C.

    1959-07-14

    A cation exchange prccess is described for separating protactinium values from thorium values whereby they are initially adsorbed together from an aqueous 0.1 to 2 N hydrochloric acid on a cation exchange resin in a column. Then selectively eluting the thorium by an ammonium sulfate solution and subsequently eluting the protactinium by an oxalate solution.

  17. pi-Dimers of end-capped oligopyrrole cation radicals

    NARCIS (Netherlands)

    Haare, van J.A.E.H.; Groenendaal, L.; Havinga, E.E.; Janssen, R.A.J.; Meijer, E.W.

    1996-01-01

    In two consecutive one-electron oxidations, oligopyrroles substituted with phenyl capping groups (PhPynPh, n = 2–4) can be oxidized reversibly to give stable cation radicals and dications. Spectroelectrochemical studies give direct evidence that diamagnetic p-dimers of cation radicals are formed in

  18. Cation exchange of 53 elements in nitric acid

    International Nuclear Information System (INIS)

    Marsh, S.F.; Alarid, J.E.; Hamond, C.F.; McLeod, M.J.; Roensch, F.R.; Rein, J.E.

    1978-02-01

    Cation-exchange distribution data are presented for 53 elements from 3 to 12M HNO 3 for three strong-acid resins, having cross-linkages of 8%, 4%, and macroporous. Data obtained by 16- to 18-h dynamic batch contacts are compared to cation-exchange distribution data from strong HCl and HClO 4

  19. Cationic Antimicrobial Peptides Inactivate Shiga Toxin-Encoding Bacteriophages

    Directory of Open Access Journals (Sweden)

    Manuel E. Del Cogliano

    2017-12-01

    Full Text Available Shiga toxin (Stx is the principal virulence factor during Shiga toxin-producing Escherichia coli (STEC infections. We have previously reported the inactivation of bacteriophage encoding Stx after treatment with chitosan, a linear polysaccharide polymer with cationic properties. Cationic antimicrobial peptides (cAMPs are short linear aminoacidic sequences, with a positive net charge, which display bactericidal or bacteriostatic activity against a wide range of bacterial species. They are promising novel antibiotics since they have shown bactericidal effects against multiresistant bacteria. To evaluate whether cationic properties are responsible for bacteriophage inactivation, we tested seven cationic peptides with proven antimicrobial activity as anti-bacteriophage agents, and one random sequence cationic peptide with no antimicrobial activity as a control. We observed bacteriophage inactivation after incubation with five cAMPs, but no inactivating activity was observed with the random sequence cationic peptide or with the non-alpha helical cAMP Omiganan. Finally, to confirm peptide-bacteriophage interaction, zeta potential was analyzed by following changes on bacteriophage surface charges after peptide incubation. According to our results we could propose that: (1 direct interaction of peptides with phage is a necessary step for bacteriophage inactivation, (2 cationic properties are necessary but not sufficient for bacteriophage inactivation, and (3 inactivation by cationic peptides could be sequence (or structure specific. Overall our data suggest that these peptides could be considered a new family of molecules potentially useful to decrease bacteriophage replication and Stx expression.

  20. Cation substitution induced blue-shift of optical band gap

    Indian Academy of Sciences (India)

    Cation substitution induced blue-shift of optical band gap in nanocrystalline Zn ( 1 − x ) Ca x O thin films deposited by sol–gel dip coating technique ... thin films giving 13.03% enhancement in theenergy gap value due to the electronic perturbation caused by cation substitution as well as deterioration in crystallinity.

  1. In vivo toxicity of cationic micelles and liposomes

    DEFF Research Database (Denmark)

    Knudsen, Kristina Bram; Northeved, Helle; Ek, Pramod Kumar

    2015-01-01

    This study investigated toxicity of nanocarriers comprised of cationic polymer and lipid components often used in gene and drug delivery, formulated as cationic micelles and liposomes. Rats were injected intravenously with 10, 25 or 100 mg/kg and sacrificed after 24 or 48 h, or 24 h after the las...

  2. Inversion of membrane surface charge by trivalent cations probed with a cation-selective channel.

    Science.gov (United States)

    Gurnev, Philip A; Bezrukov, Sergey M

    2012-11-13

    We demonstrate that the cation-selective channel formed by gramicidin A can be used as a reliable sensor for studying the multivalent ion accumulation at the surfaces of charged lipid membranes and the "charge inversion" phenomenon. In asymmetrically charged membranes with the individual leaflets formed from pure negative and positive lipids bathed by 0.1 M CsCl solutions the channel exhibits current rectification, which is comparable to that of a typical n/p semiconductor diode. We show that even at these highly asymmetrical conditions the channel conductance can be satisfactorily described by the electrodiffusion equation in the constant field approximation but, due to predictable limitations, only when the applied voltages do not exceed 50 mV. Analysis of the changes in the voltage-dependent channel conductance upon addition of trivalent cations allows us to gauge their interactions with the membrane surface. The inversion of the sign of the effective surface charge takes place at the concentrations, which correlate with the cation size. Specifically, these concentrations are close to 0.05 mM for lanthanum, 0.25 mM for hexaamminecobalt, and 4 mM for spermidine.

  3. Relationship between the supramolecular structure and the transfection efficiency for cationic micelle/DNA complexes

    International Nuclear Information System (INIS)

    Sakuragi, Mina; Kusuki, Shota; Hamada, Emi; Sakurai, Kazuo; Masunaga, Hiroyasu; Sasaki, Sono

    2009-01-01

    We synthesized a cationic lipid benzyl amine derivative bearing a primary amine as the head group and evaluated its transfection efficiency as a DNA carrier. A lipoplex (complex of DNA and lipid micelle) was prepared by mixing BA and two neutral colipids (DOPE and DLPC). When we compared the transfection efficiency at various compositions, we found that B-lipoplex (BA/DOPE/DLPC=1/2/1) was the most efficient while A-lipoplex (BA/DLPC=1/1) showed no transfection. We compared A-lipoplex with B-lipoplex by use of SAXS, fluorescence spectrum of ethidium bromide and pyrene. These results indicated that A-lipoplex formed a lamellar or cylinder structure within which DNA molecules were trapped in the lipid alkyl chain, while B-lipoplex formed cylinders where DNAs were intercalated between the lipid micelle cylinders. (author)

  4. Structure-activity correlation in transfection promoted by pyridinium cationic lipids.

    Science.gov (United States)

    Parvizi-Bahktar, P; Mendez-Campos, J; Raju, L; Khalique, N A; Jubeli, E; Larsen, H; Nicholson, D; Pungente, M D; Fyles, T M

    2016-03-21

    The efficiency of the transfection of a plasmid DNA encoding a galactosidase promoted by a series of pyridinium lipids in mixtures with other cationic lipids and neutral lipids was assessed in CHO-K1 cells. We identify key molecular parameters of the lipids in the mixture - clog P, lipid length, partial molar volume - to predict the morphology of the lipid-DNA lipoplex and then correlate these same parameters with transfection efficiency in an in vitro assay. We define a Transfection Index that provides a linear correlation with normalized transfection efficiency over a series of 90 different lipoplex compositions. We also explore the influence of the same set of molecular parameters on the cytotoxicity of the formulations.

  5. Use of cation selective membrane and acid addition for PH control in two-dimensional electrokinetic remediation of copper

    Energy Technology Data Exchange (ETDEWEB)

    Chan, M.S.M.; Lynch, R.J. [Cambridge Univ., Engineering Dept. (United Kingdom); Ilett, D.J. [AEA Technology, Harwell, Oxfordshire (United Kingdom)

    2001-07-01

    The feasibility of using a combination of a cation selective membrane and acid addition for pH control in electrokinetic remediation to toxic and heavy metals from low-permeability soil has been investigated. The high pH generated during the remediation process, as a result of surplus OH{sup -} ions, may cause metal ions to precipitate as hydroxides at or near the cathodes. This region of high pH is known to be associated with high electrical resistance, which limits the remediation efficiency by inhibiting current flow through the soil. One way to control pH is by adding acid to neutralize the OH{sup -} ions. However, preliminary work showed that addition of acid to the cathodic region was not effective in preventing the spread of the alkaline zone from cathodes toward anodes. Precipitates were formed before metal ions reached the cathodic region. Therefore, another method of pH control was investigated, using a cation selective membrane to enhance the electrokinetic process. The membrane was placed in front of the cathodes to contain the OH{sup -} ions generated, and confine the precipitates of metal hydroxide to a small cathodic region. The clean-up of a contaminated site was modelled in a rectangular tank, using silt as the low permeability soul and copper to simulate the contamination. The objective was to redistribute the contaminant so as to concentrate it into a small area. Three experiments were performed with the following methods of pH control: (1) acid addition, (2) use of a cation selective membrane and (3) a combination of acid addition and a cation selective membrane. Using the combined approach, it was found that 75% of the target clean-up section (bounded by the cation selective membrane and the anodes) had more than 40% of the initial copper removed. The general efficiency of remediation increased in the following order. (orig.)

  6. Neutral beam in ALVAND IIC tokamak

    International Nuclear Information System (INIS)

    Ghrannevisse, M.; Moradshahi, M.; Avakian, M.

    1992-01-01

    Neutral beams have a wide application in tokamak experiments. It used to heat; fuel; adjust electric potentials in plasmas and diagnose particles densities and momentum distributions. It may be used to sustain currents in tokamaks to extend the pulse length. A 5 KV; 500 mA ion source has been constructed by plasma physics group, AEOI and it used to produce plasma and study the plasma parameters. Recently this ion source has been neutralized and it adapted to a neutral beam source; and it used to heat a cylindrical DC plasma and the plasma of ALVAND IIC Tokamak which is a small research tokamak with a minor radius of 12.6 cm, and a major radius of 45.5 cm. In this paper we report the neutralization of the ion beam and the results obtained by injection of this neutral beam into plasmas. (author) 2 refs., 4 figs

  7. Tax Neutrality on International Capital Investments

    Directory of Open Access Journals (Sweden)

    Gizem KAPUCU

    2017-07-01

    Full Text Available The tax policies which states follow with regard to developing technology and capital investments with raising mobility due to globalism are need to be discussed in its legal basis. The principle of tax neutrality has the aim of being legal foundation for these policies. According to this, the neutrality principle in taxation of international capital investments is provided with two measures, namely; not effecting the investment decision and not discriminate between investments. In this paper, initially focused on the conceptual framework and the foundations of the tax neutrality principle and later capital export neutrality and capital import neutrality are considered and explained with regard to international capital movements. Moreover, conformity and diversion to the principle of the current situation and regulations in OECD, EU and Turkey are examined.

  8. Sputtering of neutral and ionic indium clusters

    International Nuclear Information System (INIS)

    Ma, Z.; Coon, S.R.; Calaway, W.F.; Pellin, M.J.; Gruen, D.M.; Von Nagy-Felsobuki, E.I.

    1993-01-01

    Secondary neutral and secondary ion cluster yields were measured during the sputtering of a polycrystalline indium surface by normally incident ∼4 keV Ar + ions. In the secondary neutral mass spectra, indium clusters as large as In 32 were observed. In the secondary ion mass spectra, indium clusters up to In 18 + were recorded. Cluster yields obtained from both the neutral and ion channel exhibited a power law dependence on the number of constituent atoms, n, in the cluster, with the exponents measured to be -5.6 and -4. 1, respectively. An abundance drop was observed at n=8, 15, and 16 in both the neutral and ion yield distributions suggesting that the stability of the ion (either secondary ion or photoion) plays a significant role in the observed distributions. In addition, our experiments suggest that unimolecular decomposition of the neutral cluster may also plays an important role in the measured yield distributions

  9. Neutral-beam-heating applications and development

    International Nuclear Information System (INIS)

    Menon, M.M.

    1981-01-01

    The technique of heating the plasma in magnetically confined fusion devices by the injection of intense beams of neutral atoms is described. The basic principles governing the physics of neutral beam heating and considerations involved in determining the injection energy, power, and pulse length required for a fusion reactor are discussed. The pertinent experimental results from various fusion devices are surveyed to illustrate the efficacy of this technique. The second part of the paper is devoted to the technology of producing the neutral beams. A state-of-the-art account o the development of neutral injectors is presented, and the prospects for utilizing neutral injection to heat the plasma in a fusion reactor are examined

  10. ORNL neutral-beam program in 1978

    International Nuclear Information System (INIS)

    Whealton, J.H.

    1982-12-01

    This report was presented at the ion source workshop held at Culham Laboratory, Abingdon, Oxfordshire, in 1978. Because the proceedings of that conference are unavailable, and because the material in this report is still not to be found elsewhere, it is issued as a laboratory report. The neutral beam group at Oak Ridge National Laboratory has constructed neutral beam generators for the ORMAK and PLT devices, is presently constructing neutral beam devices for the ISX and PDX devices, and is contemplating the construction of neutral beam systems for the advanced TNS device. These neutral beam devices stem from the pioneering work on ion sources of G.G. Kelley and O.B. Morgan. We describe the ion sources under development at this laboratory, the beam optics exhibited by these sources, as well as some theoretical considerations, and finally the remainder of the beamline design

  11. Cation interdiffusion in polycrystalline calcium and strontium titanate

    International Nuclear Information System (INIS)

    Butler, E.P.; Jain, H.; Smyth, D.M.

    1991-01-01

    This paper discusses a method that has been developed to study bulk lattice interdiffusion between calcium and strontium titanate by fabrication of a diffusion couple using cosintering. The measured interdiffusion coefficients, D(C), indicate that strontium impurity diffusion in calcium titanate occurs at a faster rate than calcium impurity diffusion in strontium titanate. These interdiffusion coefficients are composition independent when the concentration of the calcium cation exceeds that of the strontium cation; otherwise D(C) is strongly composition dependent. Investigations into the effect of cation nonstoichiometry give results that are consistent with a defect incorporation reaction in which excess TiO 2 , within the solid solubility limit, produces A-site cation vacancies as compensating defects. The interdiffusion coefficients increase with increasing concentrations of TiO 2 , so it is concluded that interdiffusion of these alkaline-earth cations in their titanates occurs via a vacancy mechanism

  12. Thermochemical stability of Soviet macroporous sulfonated cation-exchangers

    Energy Technology Data Exchange (ETDEWEB)

    Rukhlyada, N.N.; Plotnikova, V.P.; Roginskaya, B.S.; Znamenskii, Yu.P.; Zavodovskaya, A.S.; Dobrova, E.I.

    1988-10-20

    The purpose of this work was to study the influence of macroporosity on the thermochemical stability of sulfonated cation-exchangers. The investigations were carried out on commercial macroporous sulfonated cation-exchangers based on styrene-divinylbenzene copolymers. Study of the thermochemical stability of macroporous sulfonated cation-exchangers in dilute hydrogen peroxide solutions showed that the type of macroporosity has virtually no influence on their stability. The determining factor in thermal stability of macroporous cation-exchangers, as of the gel type, is the degree of cross-linking of the polymer matrix. The capacity loss of macroporous cation-exchangers during oxidative thermolysis is caused by destruction of the macromolecular skeleton and elution of fragments of polar chains containing sulfo groups into the solution.

  13. Increasing Base Cations in Streams: Another Legacy of Deicing Salts?

    Science.gov (United States)

    Helton, A. M.; Barclay, J. R.; Bellucci, C.; Rittenhouse, C.

    2017-12-01

    Elevated use of deicing salts directly increases sodium chloride inputs to watersheds. Sodium can accumulate in soils over time and has the potential to leach other cations (e.g., calcium, magnesium, and potassium) from the soil through cation exchange. We hypothesize that increased use of deicing salts results in a legacy of soils depleted in non-sodium base cations with loss of cations to receiving waters. The goal of this project is to quantify temporal trends in base cations and chloride in streams and rivers across the United States. We used Weighted Regressions on Time, Discharge, and Season (WRTDS) to analyze trends in base cations. Our preliminary analysis of 10 rivers in Connecticut with chemical periods of record ranging from 24 - 64 years (median = 55 years), shows that the flux of base cations is increasing in all sites (25 - 366 103 meq ha-1 yr-1 yr-1), driven largely by increases in sodium (23 - 222 103 meq ha-1 yr-1 yr-1), the dominant cation in 7 of the sites. Chloride is also increasing at all sites (26 - 261 103 meq ha-1 yr-1 yr-1), which, in combination with salt use trends, suggests a road salt source for the increased sodium. Non-sodium cations are also increasing in 9 of the sites (8 - 54 103 meq ha-1 yr-1 yr-1), though they are not directly added with most deicing salts. We will compare these trends to other long-term sites across the United States, and quantify relationships between cation trends and land cover, road density, and snowfall.

  14. Light-induced cation exchange for copper sulfide based CO2 reduction.

    Science.gov (United States)

    Manzi, Aurora; Simon, Thomas; Sonnleitner, Clemens; Döblinger, Markus; Wyrwich, Regina; Stern, Omar; Stolarczyk, Jacek K; Feldmann, Jochen

    2015-11-11

    Copper(I)-based catalysts, such as Cu2S, are considered to be very promising materials for photocatalytic CO2 reduction. A common synthesis route for Cu2S via cation exchange from CdS nanocrystals requires Cu(I) precursors, organic solvents, and neutral atmosphere, but these conditions are not compatible with in situ applications in photocatalysis. Here we propose a novel cation exchange reaction that takes advantage of the reducing potential of photoexcited electrons in the conduction band of CdS and proceeds with Cu(II) precursors in an aqueous environment and under aerobic conditions. We show that the synthesized Cu2S photocatalyst can be efficiently used for the reduction of CO2 to carbon monoxide and methane, achieving formation rates of 3.02 and 0.13 μmol h(-1) g(-1), respectively, and suppressing competing water reduction. The process opens new pathways for the preparation of new efficient photocatalysts from readily available nanostructured templates.

  15. Interactions between fluorinated cationic guar gum and surfactants in the dilute and semi-dilute solutions.

    Science.gov (United States)

    Wang, Chen; Li, Xiaorui; Li, Peizhi; Niu, Yuhua

    2014-01-01

    The interactions between the fluorinated cationic guar gum (FCGG) and ionic surfactants including cetyl trimethyl ammonium bromide (CTAB) and sodium lauryl sulfate (SDS) were studied by light scattering, fluorescence spectroscopy, UV-spectrophotometer, (19)F NMR and dynamic rheometer, respectively. The FCGG is prepared with cationic guar gum, isophorone diisocyanate and 2,2,3,4,4,4-hexafluoro-1-butanol. The results show that, with the addition of the surfactants, the stretching degree of the FCGG chains is increased in the FCGG/CTAB solutions, while the dramatical shrinking of FCGG chain, the phase separation and the re-stretched macromolecules appear successively because of the electricity neutralization reaction in the FCGG/SDS system. The mixed hydrophobic domains in all solutions will be reinforced and then dismantled. The solution elasticity shows up the maximum value accordingly. The surfactants can be embedded in the micro-domains and then hinder the fluorinated segmental motions. The interactions between FCGG and SDS are much stronger than those between FCGG and CTAB. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Cation depletion by the sodium pump in red cells with pathologic cation leaks. Sickle cells and xerocytes.

    Science.gov (United States)

    Joiner, C H; Platt, O S; Lux, S E

    1986-12-01

    The mechanism by which sickle cells and xerocytic red cells become depleted of cations in vivo has not been identified previously. Both types of cells exhibit elevated permeabilities to sodium and potassium, in the case of sickle cells, when deoxygenated. The ouabain-insensitive fluxes of sodium and potassium were equivalent, however, in both cell types under these conditions. When incubated 18 hours in vitro, sickle cells lost cations but only when deoxygenated. This cation depletion was blocked by ouabain, removal of external potassium, or pretreatment with 4,4'-diisothiocyanostilbene-2,2'-disulfonate, which blocks the increase in cation permeability induced by deoxygenation. The loss of cation exhibited by oxygenated xerocytes similarly incubated was also blocked by ouabain. These data support the hypothesis that the elevated "passive" cation fluxes of xerocytes and deoxygenated sickle cells are not directly responsible for cation depletion of these cells; rather, these pathologic leaks interact with the sodium pump to produce a net loss of cellular cation.

  17. Comparison of "type I" and "type II" organic cation transport by organic cation transporters and organic anion-transporting polypeptides

    NARCIS (Netherlands)

    Van Montfoort, JE; Muller, M; Groothuis, GMM; Meijer, DKF; Koepsell, H; Meier, PJ

    Previous inhibition studies with taurocholate and cardiac glycosides suggested the presence of separate uptake systems for small "type I" (system1) and for bulky "type II" (system2) organic cations in rat hepatocytes. To identify the transport systems involved in type I and type II organic cation

  18. IRMPD Action Spectroscopy of Alkali Metal Cation-Cytosine Complexes: Effects of Alkali Metal Cation Size on Gas Phase Conformation

    NARCIS (Netherlands)

    Yang, B.; Wu, R.R.; Polfer, N.C.; Berden, G.; Oomens, J.; Rodgers, M.T.

    2013-01-01

    The gas-phase structures of alkali metal cation-cytosine complexes generated by electrospray ionization are probed via infrared multiple photon dissociation (IRMPD) action spectroscopy and theoretical calculations. IRMPD action spectra of five alkali metal cation-cytosine complexes exhibit both

  19. Dissociation of protonated N-(3-phenyl-2H-chromen-2-ylidene)-benzenesulfonamide in the gas phase: cyclization via sulfonyl cation transfer.

    Science.gov (United States)

    Wang, Shanshan; Dong, Cheng; Yu, Lian; Guo, Cheng; Jiang, Kezhi

    2016-01-15

    In the tandem mass spectrometry of protonated N-(3-phenyl-2H-chromen-2-ylidene)benzenesulfonamides, the precursor ions have been observed to undergo gas-phase dissociation via two competing channels: (a) the predominant channel involves migration of the sulfonyl cation to the phenyl C atom and the subsequent loss of benzenesulfinic acid along with cyclization reaction, and (b) the minor one involves dissociation of the precursor ion to give an ion/neutral complex of [sulfonyl cation/imine], followed by decomposition to afford sulfonyl cation or the INC-mediated electron transfer to give an imine radical cation. The proposed reaction channels have been supported by theoretical calculations and D-labeling experiments. The gas-phase cyclization reaction originating from the N- to C-sulfonyl cation transfer has been first reported to the best of our knowledge. For the substituted sulfonamides, the presence of electron-donating groups (R(2) -) at the C-ring effectively facilitates the reaction channel of cyclization reaction, whereas that of electron-withdrawing groups inhibits this pathway. Copyright © 2015 John Wiley & Sons, Ltd.

  20. Anaerobic toxicity of cationic silver nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Gitipour, Alireza; Thiel, Stephen W. [Biomedical, Chemical, and Environmental Engineering, University of Cincinnati, Cincinnati, OH (United States); Scheckel, Kirk G. [USEPA, Office of Research and Development, Cincinnati, OH (United States); Tolaymat, Thabet, E-mail: tolaymat.thabet@epa.gov [USEPA, Office of Research and Development, Cincinnati, OH (United States)

    2016-07-01

    The microbial toxicity of silver nanoparticles (AgNPs) stabilized with different capping agents was compared to that of Ag{sup +} under anaerobic conditions. Three AgNPs were investigated: (1) negatively charged citrate-coated AgNPs (citrate-AgNPs), (2) minimally charged polyvinylpyrrolidone coated AgNPs (PVP-AgNPs) and (3) positively charged branched polyethyleneimine coated AgNPs (BPEI-AgNPs). The AgNPs investigated in this experiment were similar in size (10–15 nm), spherical in shape, but varied in surface charge which ranged from highly negative to highly positive. While, at AgNPs concentrations lower than 5 mg L{sup −1}, the anaerobic decomposition process was not influenced by the presence of the nanoparticles, there was an observed impact on the diversity of the microbial community. At elevated concentrations (100 mg L{sup −1} as silver), only the cationic BPEI-AgNPs demonstrated toxicity similar in magnitude to that of Ag{sup +}. Both citrate and PVP-AgNPs did not exhibit toxicity at the 100 mg L{sup −1} as measured by biogas evolution. These findings further indicate the varying modes of action for nanoparticle toxicity and represent one of the few studies that evaluate end-of-life management concerns with regards to the increasing use of nanomaterials in our everyday life. These findings also highlight some of the concerns with a one size fits all approach to the evaluation of environmental health and safety concerns associated with the use of nanoparticles. - Highlights: • At concentrations -1 the anaerobic decomposition process was not impacted. • An impact on the microbial community at concentrations -1 were observed. • At high concentrations (100 mg L{sup −1}), the cationic BPEI-AgNPs demonstrated toxicity. • Toxicity was demonstrated without the presence of oxidative dissolution of silver. • A one size fits all approach for the evaluation of NPs may not be accurate.

  1. Cation-π interaction of the univalent sodium cation with [2.2.2]paracyclophane: Experimental and theoretical study

    Science.gov (United States)

    Makrlík, Emanuel; Sýkora, David; Böhm, Stanislav; Vaňura, Petr

    2018-02-01

    By employing electrospray ionization mass spectrometry (ESI-MS), it was proven experimentally that the univalent sodium cation (Na+) forms with [2.2.2]paracyclophane (C24H24) the cationic complex [Na(C24H24)]+. Further, applying quantum chemical DFT calculations, the most probable structure of the [Na(C24H24)]+ complex was derived. In the resulting complex with a symmetry very close to C3, the "central" cation Na+, fully located in the cavity of the parent [2.2.2]paracyclophane ligand, is bound to all three benzene rings of [2.2.2]paracyclophane via cation-π interaction. Finally, the interaction energy, E(int), of the considered cation-π complex [Na(C24H24)]+ was found to be -267.3 kJ/mol, confirming the formation of this fascinating complex species as well.

  2. The neutral species of the weak base trimethoprim is more toxic to willow trees (Salix viminalis) than the cation

    DEFF Research Database (Denmark)

    Mikes, O.; Trapp, Stefan

    2011-01-01

    The acute toxicity of the veterinary antibiotic trimethoprim (TMP) to willow trees was tested at three different pH levels in hydroponic solutions with TMP concentrations of 1, 10, 100 or 1000 mg/L. The pH variation was achieved by using ammonium (pH 4.3, low) or nitrate (pH 6.4, medium) as nitro......The acute toxicity of the veterinary antibiotic trimethoprim (TMP) to willow trees was tested at three different pH levels in hydroponic solutions with TMP concentrations of 1, 10, 100 or 1000 mg/L. The pH variation was achieved by using ammonium (pH 4.3, low) or nitrate (pH 6.4, medium...

  3. Metal cation dependence of interactions with amino acids: bond dissociation energies of Rb(+) and Cs(+) to the acidic amino acids and their amide derivatives.

    Science.gov (United States)

    Armentrout, P B; Yang, Bo; Rodgers, M T

    2014-04-24

    Metal cation-amino acid interactions are key components controlling the secondary structure and biological function of proteins, enzymes, and macromolecular complexes comprising these species. Determination of pairwise interactions of alkali metal cations with amino acids provides a thermodynamic vocabulary that begins to quantify these fundamental processes. In the present work, we expand a systematic study of such interactions by examining rubidium and cesium cations binding with the acidic amino acids (AA), aspartic acid (Asp) and glutamic acid (Glu), and their amide derivatives, asparagine (Asn) and glutamine (Gln). These eight complexes are formed using electrospray ionization and their bond dissociation energies (BDEs) are determined experimentally using threshold collision-induced dissociation with xenon in a guided ion beam tandem mass spectrometer. Analyses of the energy-dependent cross sections include consideration of unimolecular decay rates, internal energy of the reactant ions, and multiple ion-neutral collisions. Quantum chemical calculations are conducted at the B3LYP, MP2(full), and M06 levels of theory using def2-TZVPPD basis sets, with results showing reasonable agreement with experiment. At 0 and 298 K, most levels of theory predict that the ground-state conformers for M(+)(Asp) and M(+)(Asn) involve tridentate binding of the metal cation to the backbone carbonyl, amino, and side-chain carbonyl groups, although tridentate binding to the carboxylic acid group and side-chain carbonyl is competitive for M(+)(Asn). For the two longer side-chain amino acids, Glu and Gln, multiple structures are competitive. A comparison of these results to those for the smaller alkali cations, Na(+) and K(+), provides insight into the trends in binding energies associated with the molecular polarizability and dipole moment of the side chain. For all four metal cations, the BDEs are inversely correlated with the size of the metal cation and follow the order Asp < Glu

  4. Neutral sodium/bicarbonate/sulfate hot waters in geothermal systems

    Energy Technology Data Exchange (ETDEWEB)

    Mahon, W.A.J. (Dept. of Industrial and Scientific Research, Wairakei, New Zealand); Klyen, L.E.; Rhode, M.

    1980-03-01

    The least understood thermal water is a near neutral water which contains varying amounts of bicarbonate and sulfate as the major anions, low concentrations of chloride (< 30 ppM) and sodium as the major cation. In the past this water has been referred to as a sodium bicarbonate water but present studies suggest that the quantities of bicarbonate and sulfate in this water type are frequently of the same order. Of particular interest is the distribution and position of the sodium/bicarbonate/sulfate water in the same and different systems. Many hot springs in Indonesia, for example, discharge water of this composition. Present studies indicate that this water type can originate from high temperature reservoirs which form the secondary steam heated part of a normal high temperature geothermal system. The hydrological conditions producing these waters in geothermal systems are investigated and the relationship between the water type and vapor dominated systems is discussed. It is suggested that the major water type occurring in the so called vapor dominated parts of geothermal systems is this water. The water does not simply represent steam condensate, rather it consists essentially of meteoric water which has been steam heated. The water composition results from the interaction of carbon dioxide and hydrogen sulfide with meteoric water and the rocks confining this water in the aquifer.

  5. Feline Immunodeficiency Virus (FIV Neutralization: A Review

    Directory of Open Access Journals (Sweden)

    Margaret J. Hosie

    2011-10-01

    Full Text Available One of the major obstacles that must be overcome in the design of effective lentiviral vaccines is the ability of lentiviruses to evolve in order to escape from neutralizing antibodies. The primary target for neutralizing antibodies is the highly variable viral envelope glycoprotein (Env, a glycoprotein that is essential for viral entry and comprises both variable and conserved regions. As a result of the complex trimeric nature of Env, there is steric hindrance of conserved epitopes required for receptor binding so that these are not accessible to antibodies. Instead, the humoral response is targeted towards decoy immunodominant epitopes on variable domains such as the third hypervariable loop (V3 of Env. For feline immunodeficiency virus (FIV, as well as the related human immunodeficiency virus-1 (HIV-1, little is known about the factors that lead to the development of broadly neutralizing antibodies. In cats infected with FIV and patients infected with HIV-1, only rarely are plasma samples found that contain antibodies capable of neutralizing isolates from other clades. In this review we examine the neutralizing response to FIV, comparing and contrasting with the response to HIV. We ask whether broadly neutralizing antibodies are induced by FIV infection and discuss the comparative value of studies of neutralizing antibodies in FIV infection for the development of more effective vaccine strategies against lentiviral infections in general, including HIV-1.

  6. Net Neutrality: Media Discourses and Public Perception

    Directory of Open Access Journals (Sweden)

    Christine Quail

    2010-01-01

    Full Text Available This paper analyzes media and public discourses surrounding net neutrality, with particular attention to public utility philosophy, from a critical perspective. The article suggests that further public education about net neutrality would be beneficial. The first portion of this paper provides a survey of the existing literature surrounding net neutrality, highlighting the contentious debate between market-based and public interest perspectives. In order to contextualize the debate, an overview of public utility philosophy is provided, shedding light on how the Internet can be conceptualized as a public good. Following this discussion, an analysis of mainstream media is presented, exploring how the media represents the issue of net neutrality and whether or not the Internet is discussed through the lens of public utility. To further examine how the net neutrality debate is being addressed, and to see the potential impacts of media discourses on the general public, the results of a focus group are reported and analyzed. Finally, a discussion assesses the implications of the net neutrality debate as presented through media discourses, highlighting the future of net neutrality as an important policy issue.

  7. Alkali Metal Cation versus Proton and Methyl Cation Affinities: Structure and Bonding Mechanism

    NARCIS (Netherlands)

    Boughlala, Z.; Guerra, C.F.; Bickelhaupt, F.M.

    2016-01-01

    We have analyzed the structure and bonding of gas-phase Cl X and [HCl X](+) complexes for X+ = H+, CH3+, Li+, and Na+, using relativistic density functional theory (DFT). We wish to establish a quantitative trend in affinities of the anionic and neutral Lewis bases Cl- and HCl for the various

  8. Neutral Supersymmetric Higgs Boson Searches

    Energy Technology Data Exchange (ETDEWEB)

    Robinson, Stephen Luke [Imperial College, London (United Kingdom)

    2008-07-01

    In some Supersymmetric extensions of the Standard Model, including the Minimal Supersymmetric Standard Model (MSSM), the coupling of Higgs bosons to b-quarks is enhanced. This enhancement makes the associated production of the Higgs with b-quarks an interesting search channel for the Higgs and Supersymmetry at D0. The identification of b-quarks, both online and offline, is essential to this search effort. This thesis describes the author's involvement in the development of both types of b-tagging and in the application of these techniques to the MSSM Higgs search. Work was carried out on the Level-3 trigger b-tagging algorithms. The impact parameter (IP) b-tagger was retuned and the effects of increased instantaneous luminosity on the tagger were studied. An extension of the IP-tagger to use the z-tracking information was developed. A new b-tagger using secondary vertices was developed and commissioned. A tool was developed to allow the use of large multi-run samples for trigger studies involving b-quarks. Offline, a neural network (NN) b-tagger was trained combining the existing offline lifetime based b-tagging tools. The efficiency and fake rate of the NN b-tagger were measured in data and MC. This b-tagger was internally reviewed and certified by the Collaboration and now provides the official b-tagging for all analyses using the Run IIa dataset at D0. A search was performed for neutral MSSM Higgs bosons decaying to a b{bar b} pair and produced in association with one or more b-quarks. Limits are set on the cross-section times the branching ratio for such a process. The limits were interpreted in various MSSM scenarios. This analysis uses the NN b-tagger and was the first to use this tool. The analysis also relies on triggers using the Level-3 IP b-tagging tool described previously. A likelihood discriminant was used to improve the analysis and a neural network was developed to cross-check this technique. The result of the analysis has been submitted to PRL

  9. Removal of radiocesium using cation exchange resin

    International Nuclear Information System (INIS)

    Morita-Murase, Yuko; Mizumura, Ryosuke; Tachibana, Yoshitaka; Kanazawa, Hideko

    2013-01-01

    Cation exchange resins (calcium polystyrene sulfonate, Ca-resin and sodium polystyrene sulfonate, Na-resin) have been used as agents to improve hyperkerlemia. For removing 137 Cs from the human body, the adsorption ability of the resin for 137 Cs was examined and evaluated. Resin (0.03 g) and 137 Cs (ca.1 kBq) were introduced into 3 mL of water, the Japanese Pharmacopoeia 1st fluid for a dissolution test (pH 1.2) and 2nd fluid (pH 6.8), respectively, and shaken. After 1-3 hours, the 137 Cs adsorption (%) of Na-resin was 99% in water, 60% in a pH 1.2 fluid and, 66% in a pH 6.8 fluid. By adding potassium, the 137 Cs adsorption (%) of Ca-resin was reduced. However, the 137 Cs adsorption (%) of Na-resin was almost unchanged. These results show that both resins have adsorption ability for 137 Cs in the stomach and the intestines. Therefore, the proposed method will be an effective means in the case of a radiological emergency due to 137 Cs. (author)

  10. Interaction of cationic drugs with liposomes.

    Science.gov (United States)

    Howell, Brett A; Chauhan, Anuj

    2009-10-20

    Interactions between cationic drugs and anionic liposomes were studied by measuring binding of drugs and the effect of binding on liposome permeability. The measurements were analyzed in the context of a continuum model based on electrostatic interactions and a Langmuir isotherm. Experiments and modeling indicate that, although electrostatic interactions are important, the fraction of drug sequestered in the double-layer is negligible. The majority of drug enters the bilayer with the charged regions interacting with the charged lipid head groups and the lipophilic regions associated with the bilayer. The partitioning of the drug can be described by a Langmuir isotherm with the electrostatic interactions increasing the sublayer concentration of the drug. The binding isotherms are similar for all tricyclic antidepressants (TCA). Bupivacaine (BUP) binds significantly less compared to TCA because its structure is such that the charged region has minimal interactions with the lipid heads once the BUP molecule partitions inside the bilayer. Conversely, the TCAs are linear with distinct hydrophilic and lipophilic regions, allowing the lipophilic regions to lie inside the bilayer and the hydrophilic regions to protrude out. This conformation maximizes the permeability of the bilayer, leading to an increased release of a hydrophilic fluorescent dye from liposomes.

  11. Radical Cations and Acid Protection during Radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Mincher, Bruce J. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Zarzana, Christopher A. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mezyk, Stephen P. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-09-09

    Ligand molecules for used nuclear fuel separation schemes are exposed to high radiation fields and high concentrations of acid. Thus, an understanding of the complex interactions between extraction ligands, diluent, and acid is critical to understanding the performance of a separation process. The diglycolamides are ligands with important structural similarities to CMPO; however, previous work has shown that their radiolytic degradation has important mechanistic differences from CMPO. The DGAs do not enjoy radioprotection by HNO3 and the kinetics of DGA radiolytic degradation are different. CMPO degrades with pseudo-zero-order kinetics in linear fashion with absorbed dose while the DGAs degrade in pseudo-first-order, exponential fashion. This suggests that the DGAs degrade by simple reaction with some product of direct diluent radiolysis, while CMPO degradation is probably multi-step, with a slow step that is not dependent on the CMPO concentration, and mitigated by HNO3. It is thus believed that radio-protection and the zero-order radiolytic degradation kinetics are related, and that these phenomena are a function of either the formation of strong acid complexes with CMPO and/or to the presence of the CMPO phenyl ring. Experiments to test both these hypotheses have been designed and partially conducted. This report summarizes findings related to these phenomena for FY16, in satisfaction of milestone M3FT-16IN030104053. It also reports continued kinetic measurements for the reactions of the dodecane radical cation with solvent extraction ligands.

  12. Radical Cations and Acid Protection during Radiolysis

    International Nuclear Information System (INIS)

    Mincher, Bruce J.; Zarzana, Christopher A.; Mezyk, Stephen P.

    2016-01-01

    Ligand molecules for used nuclear fuel separation schemes are exposed to high radiation fields and high concentrations of acid. Thus, an understanding of the complex interactions between extraction ligands, diluent, and acid is critical to understanding the performance of a separation process. The diglycolamides are ligands with important structural similarities to CMPO; however, previous work has shown that their radiolytic degradation has important mechanistic differences from CMPO. The DGAs do not enjoy radioprotection by HNO3 and the kinetics of DGA radiolytic degradation are different. CMPO degrades with pseudo-zero-order kinetics in linear fashion with absorbed dose while the DGAs degrade in pseudo-first-order, exponential fashion. This suggests that the DGAs degrade by simple reaction with some product of direct diluent radiolysis, while CMPO degradation is probably multi-step, with a slow step that is not dependent on the CMPO concentration, and mitigated by HNO 3 . It is thus believed that radio-protection and the zero-order radiolytic degradation kinetics are related, and that these phenomena are a function of either the formation of strong acid complexes with CMPO and/or to the presence of the CMPO phenyl ring. Experiments to test both these hypotheses have been designed and partially conducted. This report summarizes findings related to these phenomena for FY16, in satisfaction of milestone M3FT-16IN030104053. It also reports continued kinetic measurements for the reactions of the dodecane radical cation with solvent extraction ligands.

  13. Evaluation of smallpox vaccines using variola neutralization.

    Science.gov (United States)

    Damon, Inger K; Davidson, Whitni B; Hughes, Christine M; Olson, Victoria A; Smith, Scott K; Holman, Robert C; Frey, Sharon E; Newman, Frances; Belshe, Robert B; Yan, Lihan; Karem, Kevin

    2009-08-01

    The search for a 'third'-generation smallpox vaccine has resulted in the development and characterization of several vaccine candidates. A significant barrier to acceptance is the absence of challenge models showing induction of correlates of protective immunity against variola virus. In this light, virus neutralization provides one of few experimental methods to show specific 'in vitro' activity of vaccines against variola virus. Here, we provide characterization of the ability of a modified vaccinia virus Ankara vaccine to induce variola virus-neutralizing antibodies, and we provide comparison with the neutralization elicited by standard Dryvax vaccination.

  14. Neutral currents, supernovae neutrinos, and nucleosynthesis

    International Nuclear Information System (INIS)

    Haxton, W.C.

    1988-01-01

    The inelastic interactions of neutrinos during stellar collapse and neutron star cooling are discussed. The primary mechanism for dissipative neutrino reactions is nuclear excitation by neutral current scattering, a process not included in standard descriptions of supernovae. Charge-current and neutral current ''preheating'' of iron lying outside the shock front appears to be significant in the few milliseconds near shock breakout. This could help produce a more energetic shock. During the cooling phase, the neutral current interactions of muon and taon neutrinos appear to be responsible for some interesting nucleosynthesis. I discuss two examples the production of fluorine and neutrino-induced r-process nucleosynthesis. 26 refs., 1 fig., 3 tabs

  15. Rare decays of neutral π and eta

    International Nuclear Information System (INIS)

    Poutissou, J.M.

    1983-09-01

    The decays of the pseudoscalar neutral mesons π degree and eta degree have provided a test of fundamental principles. The main branch, π degree → 2γ, was investigated in the late 60's in the context of current algebra and the decay rate calculated from the singular triangle diagram is in excellent agreement with experiment. Rare leptonic decays of the neutral pseudoscalar mesons are of interest because of the information they reveal about neutral currents or other exotic interactions between leptons and quarks. The author discusses recent information on the π degree → e + e - decay

  16. Soviet exoatmospheric neutral particle beam research

    International Nuclear Information System (INIS)

    Leiss, J.E.; Abrams, R.H.; Ehlers, K.W.; Farrell, J.A.; Gillespie, G.H.; Jameson, R.A.; Keefe, D.; Parker, R.K.

    1988-02-01

    This technical assessment was performed by a panel of eight U.S. scientists and engineers who are familiar with Soviet research through their own research experience, their knowledge of the published scientific literature and conference proceedings, and personal contacts with Soviet scientists and other foreign colleagues. Most of the technical components of a neutral particle beam generating system including the ion source, the accelerator, the accelerator radio frequency power supply, the beam conditioning and aiming system, and the beam neutralizer system are addressed. It does not address a number of other areas important to an exoatmospheric neutral beam system

  17. Fast Neutral Pressure Measurements in NSTX

    International Nuclear Information System (INIS)

    R. Raman; H.W. Kugel; T. Provost; R. Gernhardt; T.R. Jarboe; M.G. Bell

    2002-01-01

    Several fast neutral pressure gauges have been installed on NSTX [National Spherical Torus Experiment] to measure the vessel and divertor pressure during inductive and coaxial helicity injected (CHI) plasma operations. Modified, PDX [Poloidal Divertor Experiment]-type Penning gauges have been installed on the upper and lower divertors. Neutral pressure measurements during plasma operations from these and from two shielded fast Micro ion gauges at different toroidal locations on the vessel mid-plane are described. A new unshielded ion gauge, referred to as the In-vessel Neutral Pressure (INP) gauge is under development

  18. Negative ion formation and neutralization processes, (2)

    International Nuclear Information System (INIS)

    Sugiura, Toshio

    1982-09-01

    This review is 2nd part of the report published at January 1982 (JAERI-M-9902). A compilation includes the survey of the data of the cross sections of H - and D - ion formations and the neutralization of these ions. This is also presented new information about the photosensitization by laser beam in dissociative-resonance electron capture of sulfur hexafluoride reported by Chen et al., for reference to enhancement of D - ions in discharge. For neutralization, the data of mutual neutralization and photodetachment are also presented. (author)

  19. Effect of alkali metal cations on anodic dissolution of gold in cyanide solutions. Potentiodynamic measurement

    International Nuclear Information System (INIS)

    Bek, R.Yu.; Rogozhnikov, N.A.; Kosolapov, G.V.

    1998-01-01

    It is shown that gold dissolution rate in cyanic solutions in Li + , Na + , K + , Cs + cation series increases basically and decreases under cation concentration increasing. Cation effect on current value is caused by cations drawing in dense layer. A model of dense part of double layer with two Helmholtz planes (anion and cation) is suggested. Effect of nature and concentration of alkali metal cations on gold dissolution rate is explained on the base of the model [ru

  20. Preparation, characterization, and efficient transfection of cationic liposomes and nanomagnetic cationic liposomes

    Directory of Open Access Journals (Sweden)

    Samadikhah HR

    2011-10-01

    Full Text Available Hamid Reza Samadikhah1,*, Asia Majidi2,*, Maryam Nikkhah2, Saman Hosseinkhani11Department of Biochemistry, 2Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran *These authors contributed equally to this work Purpose: Cationic liposomes (CLs are composed of phospholipid bilayers. One of the most important applications of these particles is in drug and gene delivery. However, using CLs to deliver therapeutic nucleic acids and drugs to target organs has some problems, including low transfection efficiency in vivo. The aim of this study was to develop novel CLs containing magnetite to overcome the deficiencies. Patients and methods: CLs and magnetic cationic liposomes (MCLs were prepared using the freeze-dried empty liposome method. Luciferase-harboring vectors (pGL3 were transferred into liposomes and the transfection efficiencies were determined by luciferase assay. Firefly luciferase is one of most popular reporter genes often used to measure the efficiency of gene transfer in vivo and in vitro. Different formulations of liposomes have been used for delivery of different kinds of gene reporters. Lipoplex (liposome–plasmid DNA complexes formation was monitored by gel retardation assay. Size and charge of lipoplexes were determined using particle size analysis. Chinese hamster ovary cells were transfected by lipoplexes (liposome-pGL3; transfection efficiency and gene expression level was evaluated by luciferase assay. Results: High transfection efficiency of plasmid by CLs and novel nanomagnetic CLs was achieved. Moreover, lipoplexes showed less cytotoxicity than polyethyleneimine and Lipofectamine™. Conclusion: Novel liposome compositions (1,2-dipalmitoyl-sn-glycero-3-phosphocholine [DPPC]/dioctadecyldimethylammonium bromide [DOAB] and DPPC/cholesterol/DOAB with high transfection efficiency can be useful in gene delivery in vitro. MCLs can also be used for targeted gene delivery, due to

  1. Evaluation of phenomena affecting diffusion of cations in compacted bentonite

    International Nuclear Information System (INIS)

    Muurinen, A.; Lehikoinen, J.

    1995-04-01

    In a number of diffusion studies, contradictions between the apparent diffusivities of cations and their distribution coefficients in bentonite have been found. Two principal reasons have been offered as explanations for this discrepancy; diffusion of the sorbed cations, often called surface diffusion, and the decrease of sorption in compacted clay compared to a sorption value obtained from a batch experiment. In the study the information available from the literature on sorption-diffusion mechanisms of cations in bentonite has been compiled and re-interpreted in order to improve the understanding of the diffusion process. (103 refs., 23 figs., 8 tabs.)

  2. Microscopic theory of cation exchange in CdSe nanocrystals.

    Science.gov (United States)

    Ott, Florian D; Spiegel, Leo L; Norris, David J; Erwin, Steven C

    2014-10-10

    Although poorly understood, cation-exchange reactions are increasingly used to dope or transform colloidal semiconductor nanocrystals (quantum dots). We use density-functional theory and kinetic Monte Carlo simulations to develop a microscopic theory that explains structural, optical, and electronic changes observed experimentally in Ag-cation-exchanged CdSe nanocrystals. We find that Coulomb interactions, both between ionized impurities and with the polarized nanocrystal surface, play a key role in cation exchange. Our theory also resolves several experimental puzzles related to photoluminescence and electrical behavior in CdSe nanocrystals doped with Ag.

  3. Neutral Color Semitransparent Microstructured Perovskite Solar Cells

    KAUST Repository

    Eperon, Giles E.; Burlakov, Victor M.; Goriely, Alain; Snaith, Henry J.

    2014-01-01

    Neutral-colored semitransparent solar cells are commercially desired to integrate solar cells into the windows and cladding of buildings and automotive applications. Here, we report the use of morphological control of perovskite thin films to form

  4. Charge neutralization of small ion beam clumps

    Energy Technology Data Exchange (ETDEWEB)

    Welch, D R [Mission Research Corp., Albuquerque, NM (United States); Olson, C L; Hanson, D L [Sandia National Labs., Albuquerque, NM (United States)

    1997-12-31

    The mega-ampere currents associated with light ion fusion (LIF) require excellent charge neutralization to prevent divergence growth. As the size and space-charge potential of a beam clump or `beamlet` become small (submillimeter size and kilovolt potentials), the neutralization becomes increasingly difficult. Linear theory predicts that plasma electrons cannot neutralize potentials < {phi}{sub crit} = (1/2)m{sub e}v{sub i}{sup 2}/e, where m{sub e} is the electron mass and v{sub i} is the ion beam velocity. A non-uniform beam would, therefore, have regions with potentials sufficient to add divergence to beam clumps. The neutralization of small beamlets produced on the SABLE accelerator and in numerical simulation has supported the theory, showing a plateau in divergence growths as the potential in the beamlet exceeds {phi}{sub crit}. (author). 1 tab., 2 figs., 4 refs.

  5. UV Ionizer for Neutral Wind Mass Spectrometers

    Data.gov (United States)

    National Aeronautics and Space Administration — Current neutral particle instrumentation relies on hot cathode filaments or an electron gun for ionizing the target medium.  These ionization sources represent a...

  6. Kinetics of neutralization of Po-218

    International Nuclear Information System (INIS)

    Chu, K.D.

    1987-01-01

    In a well-defined experimental system the neutralization of polonium-218 ions was investigated as a function of the physical and chemical properties of the controlled composition atmosphere. The mobilities of Po + and PoO 2 + are determined by combining experimental results with a computer model of the system. Three neutralization mechanisms were individually studied. The small ion recombination rate has been found to be proportional to the square root of radon concentration. The electron scavenging mechanism is responsible for the neutralization of Po + in NO 2 or H 2 O in nitrogen. When PoO 2 + is formed, the electron transfer mechanism dominates the neutralization process. The electron is transferred to PoO 2 + from molecules with lower ionization potentials. The ionization potential of PoO 2 + is also determined to be 10.44 +/- 0.05 eV

  7. An experimenter's history of neutral currents

    International Nuclear Information System (INIS)

    Sciulli, F.

    1979-01-01

    The history of the experimental study of neutral currents, defined as the class of weak interactions engaged in by lepton pairs of net zero charge, is traced under the headings; historical motivations, experimental searches, first positive indications, neutral currents corroborated, neutrino experiments on neutral currents and some general experimental comments. It is concluded that the neutral current does exist and predicted on the basis of gauge theory ideas, and though to connect the weak and electromagnetic interactions, its very general experimental properties are quite consistent with those ideas. Among these are flavor conserving complicated isospin structure, complicated V, A structure and a structure which depends on the type (or quantum numbers) of the target. 50 references. (UK)

  8. Converting Hg-1212 to Tl-2212 via Tl-Hg cation exchange in combination with Tl cation intercalation

    International Nuclear Information System (INIS)

    Zhao Hua; Wu, Judy Z

    2007-01-01

    In a cation exchange process developed recently for epitaxy of HgBa 2 CaCu 2 O 6 (Hg-1212) thin films, TlBa 2 CaCu 2 O 7 (Tl-1212) or Tl 2 Ba 2 CaCu 2 O 9 (Tl-2212) precursor films were employed as the precursor matrices and Hg-1212 was obtained by replacing Tl cations on the precursor lattice with Hg cations. The reversibility of the cation exchange dictates directly the underlying mechanism. Following our recent success in demonstrating a complete reversibility within '1212' structure, we show the conversion from Hg-1212 to Tl-2212 can be achieved via two steps: conversion from Hg-1212 to Tl-1212 followed by Tl intercalation to form double Tl-O plans in each unit cell. The demonstrated reversibility of the cation exchange process has confirmed the process is a thermal perturbation of weakly bonded cations on the lattice and the direction of the process is determined by the population ratio between the replacing cations and that to be replaced

  9. Calibration of the sodium base cation dominance index of weathering for the River Dee catchment in north-east Scotland

    Energy Technology Data Exchange (ETDEWEB)

    Stutter, M. [Aberdeen Univ. (United Kingdom). Dept. of Plant and Soil Science; Smart, R.; Cresser, M. [York Univ. (United Kingdom). Environmental Dept.

    2002-07-01

    Previously the dominance of base cations by Na{sup +} in river water in upland catchments with low weathering rates and influenced by marine-derived aerosols has been suggested as a quantitative index of weathering rate upstream of the sampling point. Using data for 59 sites from a study of the River Dee catchment in NE Scotland, the index has been fully calibrated against catchment weathering rates and net alkalinity production, derived through input output budget methods, for both upland and agricultural catchments and over a wide range of parent materials. It is shown that the relationship between Na{sup +} dominance and weathering rate is logarithmic, rather than linear as initially suggested. The excellent correlations highlight the potential use of this Na{sup +} dominance index for the direct quantification of catchment susceptibility to acidification at fine spatial resolution, using a few simple and inexpensive measurements. Stronger correlations were observed between the % Na{sup +} dominance and net annual flux of alkalinity than between % Na{sup +} dominance and weathering rate derived from summation of base cation fluxes. This demonstrates the importance of mechanisms controlling the transport of base cations out of catchments, namely in association with organic matter and with anthropogenically derived SO{sub 4}{sup 2-}. These processes are shown to reduce the residual alkalinity derived through weathering. The partial neutralization of organic acidity by internally generated alkalinity has implications in the context of using the mass balance approach for setting critical loads for catchments. (Author)

  10. Solubilization, partial purification, and reconstitution of glutamate- and N-methyl-D-aspartate-activated cation channels from brain synaptic membranes

    International Nuclear Information System (INIS)

    Ly, A.M.; Michaelis, E.K.

    1991-01-01

    L-Glutamate-activated cation channel proteins from rat brain synaptic membranes were solubilized, partially purified, and reconstituted into liposomes. Optimal conditions for solubilization and reconstitution included treatment of the membranes with nonionic detergents in the presence of neutral phospholipids plus glycerol. Quench-flow procedures were developed to characterize the rapid kinetics of ion flux induced by receptor agonists. [ 14 C]Methylamine, a cation that permeates through the open channel of both vertebrate and invertebrate glutamate receptors, was used to measure the activity of glutamate receptor-ion channel complexes in reconstituted liposomes. L-Glutamate caused an increase in the rate of [ 14 C]methylamine influx into liposomes reconstituted with either solubilized membrane proteins or partially purified glutamate-binding proteins. Of the major glutamate receptor agonists, only N-methyl-D-aspartate activated cation fluxes in liposomes reconstituted with glutamate-binding proteins. In liposomes reconstituted with glutamate-binding proteins, N-methyl-D-aspartate- or glutamate-induced influx of NA + led to a transient increase in the influx of the lipid-permeable anion probe S 14 CN - . These results indicate the functional reconstitution of N-methyl-D-aspartate-sensitive glutamate receptors and the role of the ∼69-kDa protein in the function of these ion channels

  11. ITER neutral beam system US conceptual design

    International Nuclear Information System (INIS)

    Purgalis, P.

    1990-09-01

    In this document we present the US conceptual design of a neutral beam system for International Thermonuclear Experimental Reactor (ITER). The design incorporates a barium surface conversion D - source feeding a linear array of accelerator channels. The system uses a dc accelerator with electrostatic quadrupoles for strong focusing. A high voltage power supply that is integrated with the accelerator is presented as an attractive option. A gas neutralizer is used and residual ions exiting the neutralizer are deflected to water-cooled dumps. Cryopanels are located at the accelerator exit to pump excess gas from the source and the neutralizer, and in the ion dump cavity to pump re-neutralized ions and neutralizer gas. All the above components are packaged in compact identical, independent modules which can be removed for remote maintenance. The neutral beam system delivers 75 MW of DO at 1.3 MeV, into three ports with a total of 9 modules arranged in stacks of three modules per port . To increase reliability each module is designed to deliver up to 10 MW; this allows eight modules operating at partial capacity to deliver the required power in the event one module is out of service, and provides 20% excess capacity to improve availability. Radiation protection is provided by shielding and by locating critical components in the source and accelerator 46.5 m from the torus centerline. Neutron shielding in the drift duct and neutralizer provides the added feature of limiting conductance and thus reducing gas flow to and from the torus

  12. Neutral-particle-beam production and injection

    International Nuclear Information System (INIS)

    Post, D.; Pyle, R.

    1982-07-01

    This paper is divided into two sections: the first is a discussion of the interactions of neutral beams with confined plasmas, the second is concerned with the production and diagnosis of the neutral beams. In general we are dealing with atoms, molecules, and ions of the isotopes of hydrogen, but some heavier elements (for example, oxygen) will be mentioned. The emphasis will be on single-particle collisions; selected atomic processes on surfaces will be included

  13. Neutral signature Walker-VSI metrics

    International Nuclear Information System (INIS)

    Coley, A; McNutt, D; Musoke, N; Brooks, D; Hervik, S

    2014-01-01

    We will construct explicit examples of four-dimensional neutral signature Walker (but not necessarily degenerate Kundt) spaces for which all of the polynomial scalar curvature invariants vanish. We then investigate the properties of some particular subclasses of Ricci flat spaces. We also briefly describe some four-dimensional neutral signature Einstein spaces for which all of the polynomial scalar curvature invariants are constant. (paper)

  14. Nitrogen-neutrality: a step towards sustainability

    Science.gov (United States)

    Leip, Adrian; Leach, Allison; Musinguzi, Patrick; Tumwesigye, Trust; Olupot, Giregon; Tenywa, John Stephen; Mudiope, Joseph; Hutton, Olivia; Cordovil, Claudia M. d. S.; Bekunda, Mateete; Galloway, James

    2014-11-01

    We propose a novel indicator measuring one dimension of the sustainability of an entity in modern societies: Nitrogen-neutrality. N-neutrality strives to offset Nr releases an entity exerts on the environment from the release of reactive nitrogen (Nr) to the environment by reducing it and by offsetting the Nr releases elsewhere. N-neutrality also aims to increase awareness about the consequences of unintentional releases of nitrogen to the environment. N-neutrality is composed of two quantified elements: Nr released by an entity (e.g. on the basis of the N footprint) and Nr reduction from management and offset projects (N offset). It includes management strategies to reduce nitrogen losses before they occur (e.g., through energy conservation). Each of those elements faces specific challenges with regard to data availability and conceptual development. Impacts of Nr releases to the environment are manifold, and the impact profile of one unit of Nr release depends strongly on the compound released and the local susceptibility to Nr. As such, N-neutrality is more difficult to conceptualize and calculate than C-neutrality. We developed a workable conceptual framework for N-neutrality which was adapted for the 6th International Nitrogen Conference (N2013, Kampala, November 2013). Total N footprint of the surveyed meals at N2013 was 66 kg N. A total of US 3050 was collected from the participants and used to offset the conference’s N footprint by supporting the UN Millennium Village cluster Ruhiira in South-Western Uganda. The concept needs further development in particular to better incorporate the spatio-temporal variability of impacts and to standardize the methods to quantify the required N offset to neutralize the Nr releases impact. Criteria for compensation projects need to be sharply defined to allow the development of a market for N offset certificates.

  15. Γ-source Neutral Point Clamped Inverter

    DEFF Research Database (Denmark)

    Mo, Wei; Loh, Poh Chiang; Blaabjerg, Frede

    Transformer based Z-source inverters are recently proposed to achieve promising buck-boost capability. They have improved higher buck-boost capability, smaller size and less components count over Z-source inverters. On the other hand, neutral point clamped inverters have less switching stress...... and better output performance comparing with traditional two-level inverters. Integrating these two types of configurations can help neutral point inverters achieve enhanced votlage buck-boost capability....

  16. TFTR neutral beam injection system conceptual design

    International Nuclear Information System (INIS)

    1975-01-01

    Three subsystems are described in the following chapters: (1) Neutral Beam Injection Line; (2) Power Supplies; and (3) Controls. Each chapter contains two sections: (1) Functions and Design Requirements; this is a brief listing of the requirements of components of the subsystem. (2) Design Description; this section describes the design and cost estimates. The overall performance requirements of the neutral beam injection system are summarized. (MOW)

  17. Neutral currents without gauge theory prejudices

    International Nuclear Information System (INIS)

    Sakurai, J.J.

    1976-01-01

    The measurement of weak neutral current processes allows a determination of the space-time structure and the isospin structure of these currents. The inclusive production data and the elastic neutrino electron scattering rules out a pure V or A structure of the current. A pure isoscalar current is in disagreement with the experimental data for the one pion production off neutrinos. Further aspects of the neutral current can be determined in neutrino-nucleus-scattering experiments. (BJ) [de

  18. Negative ion formation and neutralization processes, (1)

    International Nuclear Information System (INIS)

    Sugiura, Toshio

    1982-01-01

    This review has been made preliminary for the purpose of contribute to the plasma heating by ''negative ion based neutral beam injection'' in the magnetic confinement fusion reactor. A compilation includes the survey of the general processes of negative ion formation, the data of the cross section of H - ion formation and the neutralization of H - ion, and some of new processes of H - ion formation. The data of cross section are mainly experimental, but partly include the results of theoretical calculation. (author)

  19. Nitrogen-neutrality: a step towards sustainability

    International Nuclear Information System (INIS)

    Leip, Adrian; Leach, Allison; Hutton, Olivia; Galloway, James; Musinguzi, Patrick; Tumwesigye, Trust; Olupot, Giregon; Stephen Tenywa, John; Mudiope, Joseph; Cordovil, Claudia M d S; Bekunda, Mateete

    2014-01-01

    We propose a novel indicator measuring one dimension of the sustainability of an entity in modern societies: Nitrogen-neutrality. N-neutrality strives to offset Nr releases an entity exerts on the environment from the release of reactive nitrogen (Nr) to the environment by reducing it and by offsetting the Nr releases elsewhere. N-neutrality also aims to increase awareness about the consequences of unintentional releases of nitrogen to the environment. N-neutrality is composed of two quantified elements: Nr released by an entity (e.g. on the basis of the N footprint) and Nr reduction from management and offset projects (N offset). It includes management strategies to reduce nitrogen losses before they occur (e.g., through energy conservation). Each of those elements faces specific challenges with regard to data availability and conceptual development. Impacts of Nr releases to the environment are manifold, and the impact profile of one unit of Nr release depends strongly on the compound released and the local susceptibility to Nr. As such, N-neutrality is more difficult to conceptualize and calculate than C-neutrality. We developed a workable conceptual framework for N-neutrality which was adapted for the 6th International Nitrogen Conference (N2013, Kampala, November 2013). Total N footprint of the surveyed meals at N2013 was 66 kg N. A total of US$ 3050 was collected from the participants and used to offset the conference’s N footprint by supporting the UN Millennium Village cluster Ruhiira in South-Western Uganda. The concept needs further development in particular to better incorporate the spatio-temporal variability of impacts and to standardize the methods to quantify the required N offset to neutralize the Nr releases impact. Criteria for compensation projects need to be sharply defined to allow the development of a market for N offset certificates. (paper)

  20. Applications of neutral beam and rf technologies

    International Nuclear Information System (INIS)

    Haselton, H.H.

    1987-04-01

    This presentation provides an update on the applications of neutral beams and radiofrequency (rf) power in the fusion program; highlights of the ion cyclotron heating (ICH) experiments now in progress, as well as the neutral beam experiments; and heating requirements of future devices and some of the available options. Some remarks on current drive are presented because this area of technology is one that is being considered for future devices

  1. Apparatus for neutralization of accelerated ions

    International Nuclear Information System (INIS)

    Fink, J.H.; Frank, A.M.

    1979-01-01

    Apparatus is described for neutralization of a beam of accelerated ions, such as hydrogen negative ions (H - ), using relatively efficient strip diode lasers which emit monochromatically at an appropriate wavelength (lambda = 8000 A for H - ions) to strip the excess electrons by photodetachment. A cavity, formed by two or more reflectors spaced apart, causes the laser beams to undergo multiple reflections within the cavity, thus increasing the efficiency and reducing the illumination required to obtain an acceptable percentage (approx. 85%) of neutralization

  2. Endomembrane Cation Transporters and Membrane Trafficking

    Energy Technology Data Exchange (ETDEWEB)

    Sze, Heven [Univ. of Maryland, College Park, MD (United States). Dept. of Cell Biology & Molecular Genetics

    2017-04-01

    Multicellular, as well as unicellular, organisms have evolved mechanisms to regulate ion and pH homeostasis in response to developmental cues and to a changing environment. The working hypothesis is that the balance of fluxes mediated by diverse transporters at the plasma membrane and in subcellular organelles determines ionic cellular distribution, which is critical for maintenance of membrane potential, pH control, osmolality, transport of nutrients, and protein activity. An emerging theme in plant cell biology is that cells respond and adapt to diverse cues through changes of the dynamic endomembrane system. Yet we know very little about the transporters that might influence the operation of the secretory system in plants. Here we focus on transporters that influence alkali cation and pH homeostasis, mainly in the endomembrane/ secretory system. The endomembrane system of eukaryote cells serves several major functions: i) sort cargo (e.g. enzymes, transporters or receptors) to specific destinations, ii) modulate the protein and lipid composition of membrane domains through remodeling, and iii) determine and alter the properties of the cell wall through synthesis and remodeling. We had uncovered a novel family of predicted cation/H+ exchangers (CHX) and K+ efflux antiporters (KEA) that are prevalent in higher plants, but rare in metazoans. We combined phylogenetic and transcriptomic analyses with molecular genetic, cell biological and biochemical studies, and have published the first reports on functions of plant CHXs and KEAs. CHX studied to date act at the endomembrane system where their actions are distinct from the better-studied NHX (Na/K-H+ exchangers). Arabidopsis thaliana CHX20 in guard cells modulate stomatal opening, and thus is significant for vegetative survival. Other CHXs ensure reproductive success on dry land, as they participate in organizing pollen walls, targeting of pollen tubes to the ovule or promoting

  3. Negative ion based neutral beams for plasma heating

    International Nuclear Information System (INIS)

    Prelec, K.

    1978-01-01

    Neutral beam systems based on negative ions have been considered because of a high expected power efficiency. Methods for the production, acceleration and neutralization of negative ions will be reviewed and possibilities for an application in neutral beam lines explored

  4. Design of the ITER Neutral Beam injectors

    International Nuclear Information System (INIS)

    Hemsworth, R.S.; Feist, J.; Hanada, M.; Heinemann, B.; Inoue, T.; Kuessel, E.; Kulygin, V.; Krylov, A.; Lotte, P.; Miyamoto, K.; Miyamoto, N.; Murdoch, D.; Nagase, A.; Ohara, Y.; Okumura, Y.; Pamela, J.; Panasenkov, A.; Shibata, K.; Tanii, M.

    1996-01-01

    This paper describes the Neutral Beam Injection system which is presently being designed in Europe, Japan and Russia, with co-ordination by the Joint Central Team of ITER at Naka, Japan. The proposed system consists of three negative ion based neutral injectors, delivering a total of 50 MW of 1 MeV D 0 to the ITER plasma for pulse length of ≥1000 s. The injectors each use a single caesiated volume arc discharge negative ion source, and a multi-grid, multi-aperture accelerator, to produce about 40 A of 1 MeV D - . This will be neutralized in a sub-divided gas neutralizer, which has a conversion efficiency of about 60%. The charged fraction of the beam emerging from the neutralizer is dumped in an electrostatic residual ion dump. A water cooled calorimeter can be moved into the beam path to intercept the neutral beam, allowing commissioning of the injector independent of ITER. copyright 1996 American Institute of Physics

  5. Neutral particle kinetics in fusion devices

    International Nuclear Information System (INIS)

    Tendler, M.; Heifetz, D.

    1986-05-01

    The theory of neutral particle kinetics treats the transport of mass, momentum, and energy in a plasma due to neutral particles which themselves are unaffected by magnetic fields. This transport affects the global power and particle balances in fusion devices, as well as profile control and plasma confinement quality, particle and energy fluxes onto device components, performance of pumping systems, and the design of diagnostics and the interpretation of their measurements. This paper reviews the development of analytic, numerical, and Monte Carlo methods of solving the time-independent Boltzmann equation describing neutral kinetics. These models for neutral particle behavior typically use adaptations of techniques developed originally for computing neutron transport, due to the analogy between the two phenomena, where charge-exchange corresponds to scattering and ionization to absorption. Progress in the field depends on developing multidimensional analytic methods, and obtaining experimental data for the physical processes of wall reflection, the neutral/plasma interaction, and for processes in fusion devices which are directly related to neutral transport, such as H/sub α/ emission rates, plenum pressures, and charge-exchange emission spectra

  6. Neutral particle kinetics in fusion devices

    Energy Technology Data Exchange (ETDEWEB)

    Tendler, M.; Heifetz, D.

    1986-05-01

    The theory of neutral particle kinetics treats the transport of mass, momentum, and energy in a plasma due to neutral particles which themselves are unaffected by magnetic fields. This transport affects the global power and particle balances in fusion devices, as well as profile control and plasma confinement quality, particle and energy fluxes onto device components, performance of pumping systems, and the design of diagnostics and the interpretation of their measurements. This paper reviews the development of analytic, numerical, and Monte Carlo methods of solving the time-independent Boltzmann equation describing neutral kinetics. These models for neutral particle behavior typically use adaptations of techniques developed originally for computing neutron transport, due to the analogy between the two phenomena, where charge-exchange corresponds to scattering and ionization to absorption. Progress in the field depends on developing multidimensional analytic methods, and obtaining experimental data for the physical processes of wall reflection, the neutral/plasma interaction, and for processes in fusion devices which are directly related to neutral transport, such as H/sub ..cap alpha../ emission rates, plenum pressures, and charge-exchange emission spectra.

  7. Role of the Cationic C-Terminal Segment of Melittin on Membrane Fragmentation.

    Science.gov (United States)

    Therrien, Alexandre; Fournier, Alain; Lafleur, Michel

    2016-05-05

    The widespread distribution of cationic antimicrobial peptides capable of membrane fragmentation in nature underlines their importance to living organisms. In the present work, we determined the impact of the electrostatic interactions associated with the cationic C-terminal segment of melittin, a 26-amino acid peptide from bee venom (net charge +6), on its binding to model membranes and on the resulting fragmentation. In order to detail the role played by the C-terminal charges, we prepared a melittin analogue for which the four cationic amino acids in positions 21-24 were substituted with the polar residue citrulline, providing a peptide with the same length and amphiphilicity but with a lower net charge (+2). We compared the peptide bilayer affinity and the membrane fragmentation for bilayers prepared from 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)/1,2-dipalmitoyl-sn-glycero-3-phospho-l-serine (DPPS) mixtures. It is shown that neutralization of the C-terminal considerably increased melittin affinity for zwitterionic membranes. The unfavorable contribution associated with transferring the cationic C-terminal in a less polar environment was reduced, leaving the hydrophobic interactions, which drive the peptide insertion in bilayers, with limited counterbalancing interactions. The presence of negatively charged lipids (DPPS) in bilayers increased melittin binding by introducing attractive electrostatic interactions, the augmentation being, as expected, greater for native melittin than for its citrullinated analogue. The membrane fragmentation power of the peptide was shown to be controlled by electrostatic interactions and could be modulated by the charge carried by both the membrane and the lytic peptide. The analysis of the lipid composition of the extracted fragments from DPPC/DPPS bilayers revealed no lipid specificity. It is proposed that extended phase separations are more susceptible to lead to the extraction of a lipid species in a specific manner

  8. Acetone n-radical cation internal rotation spectrum: The torsional potential surface

    International Nuclear Information System (INIS)

    Shea, Dana A.; Goodman, Lionel; White, Michael G.

    2000-01-01

    The one color REMPI and two color ZEKE-PFI spectra of acetone-d 3 have been recorded. The 3p x Rydberg state of acetone-d 3 lies at 59 362.3 cm-1 and both of the torsional modes are visible in this spectrum. The antigearing Rydberg (a 2 ) mode, v 12 * , has a frequency of 62.5 cm-1, while the previously unobserved gearing (b 1 ) mode, v 17 * , is found at 119.1 cm-1. An ionization potential of 78 299.6 cm-1 for acetone-d 3 has been measured. In acetone-d 3 n-radical cation ground state, the fundamentals of both of the torsional modes have been observed, v 12 + at 51.0 cm-1 and v 17 + at 110.4 cm-1, while the first overtone of v 12 + has been measured at 122.4 cm-1. Deuterium shifts show that v 12 + behaves like a local C 3v rotor, but that v 17 + is canonical. Combining this data with that for acetone-d 0 and aacetone-d 6 has allowed us to fit the observed frequencies to a torsional potential energy surface based on an ab initio C 2v cation ground state geometry. This potential energy surface allows for prediction of the v 17 vibration in acetone-d 0 and acetone-d 6 . The barrier to synchronous rotation is higher in the cation ground state than in the neutral ground state, but significantly lower than in the 3s Rydberg state. The 3p x Rydberg and cation ground state potential energy surfaces are found to be very similar to each other, strongly supporting the contention that the 3p x Rydberg state has C 2v geometry and is a good model for the ion core. The altered 3s Rydberg state potential surface suggests this state has significant valence character. (c) 2000 American Institute of Physics

  9. Automated Facial Coding Software Outperforms People in Recognizing Neutral Faces as Neutral from Standardized Datasets

    Directory of Open Access Journals (Sweden)

    Peter eLewinski

    2015-09-01

    Full Text Available Little is known about people’s accuracy of recognizing neutral faces as neutral. In this paper, I demonstrate the importance of knowing how well people recognize neutral faces. I contrasted human recognition scores of 100 typical, neutral front-up facial images with scores of an arguably objective judge – automated facial coding (AFC software. I hypothesized that the software would outperform humans in recognizing neutral faces because of the inherently objective nature of computer algorithms. Results confirmed this hypothesis. I provided the first-ever evidence that computer software (90% was more accurate in recognizing neutral faces than people were (59%. I posited two theoretical mechanisms, i.e. smile-as-a-baseline and false recognition of emotion, as possible explanations for my findings.

  10. Cation binding to 15-TBA quadruplex DNA is a multiple-pathway cation-dependent process.

    Science.gov (United States)

    Reshetnikov, Roman V; Sponer, Jiri; Rassokhina, Olga I; Kopylov, Alexei M; Tsvetkov, Philipp O; Makarov, Alexander A; Golovin, Andrey V

    2011-12-01

    A combination of explicit solvent molecular dynamics simulation (30 simulations reaching 4 µs in total), hybrid quantum mechanics/molecular mechanics approach and isothermal titration calorimetry was used to investigate the atomistic picture of ion binding to 15-mer thrombin-binding quadruplex DNA (G-DNA) aptamer. Binding of ions to G-DNA is complex multiple pathway process, which is strongly affected by the type of the cation. The individual ion-binding events are substantially modulated by the connecting loops of the aptamer, which play several roles. They stabilize the molecule during time periods when the bound ions are not present, they modulate the route of the ion into the stem and they also stabilize the internal ions by closing the gates through which the ions enter the quadruplex. Using our extensive simulations, we for the first time observed full spontaneous exchange of internal cation between quadruplex molecule and bulk solvent at atomistic resolution. The simulation suggests that expulsion of the internally bound ion is correlated with initial binding of the incoming ion. The incoming ion then readily replaces the bound ion while minimizing any destabilization of the solute molecule during the exchange. © The Author(s) 2011. Published by Oxford University Press.

  11. Cation binding to 15-TBA quadruplex DNA is a multiple-pathway cation-dependent process

    Science.gov (United States)

    Reshetnikov, Roman V.; Sponer, Jiri; Rassokhina, Olga I.; Kopylov, Alexei M.; Tsvetkov, Philipp O.; Makarov, Alexander A.; Golovin, Andrey V.

    2011-01-01

    A combination of explicit solvent molecular dynamics simulation (30 simulations reaching 4 µs in total), hybrid quantum mechanics/molecular mechanics approach and isothermal titration calorimetry was used to investigate the atomistic picture of ion binding to 15-mer thrombin-binding quadruplex DNA (G-DNA) aptamer. Binding of ions to G-DNA is complex multiple pathway process, which is strongly affected by the type of the cation. The individual ion-binding events are substantially modulated by the connecting loops of the aptamer, which play several roles. They stabilize the molecule during time periods when the bound ions are not present, they modulate the route of the ion into the stem and they also stabilize the internal ions by closing the gates through which the ions enter the quadruplex. Using our extensive simulations, we for the first time observed full spontaneous exchange of internal cation between quadruplex molecule and bulk solvent at atomistic resolution. The simulation suggests that expulsion of the internally bound ion is correlated with initial binding of the incoming ion. The incoming ion then readily replaces the bound ion while minimizing any destabilization of the solute molecule during the exchange. PMID:21893589

  12. Use of marker ion and cationic surfactant plastic membrane electrode for potentiometric titration of cationic polyelectrolytes.

    Science.gov (United States)

    Masadome, Takashi; Imato, Toshihiko

    2003-07-04

    A plasticized poly (vinyl chloride) (PVC) membrane electrode sensitive to stearyltrimethylammonium (STA) ion is applied to the determination of cationic polyelectrolytes such as poly (diallyldimethylammonium chloride) (Cat-floc) by potentiometric titration, using a potassium poly (vinyl sulfate) (PVSK) solution as a titrant. The end-point of the titration is detected as the potential change of the plasticized PVC membrane electrode caused by decrease in the concentration of STA ion added to the sample solution as a marker ion due to the ion association reaction between the STA ion and PVSK. The effects of the concentration of STA ion, coexisting electrolytes in the sample solution and pH of the sample on the degree of the potential change at the end-point were examined. A linear relationship between the concentration of cationic polyelectrolyte and the end-point volume of the titrant exists in the concentration range from 2x10(-5) to 4x10(-4) N for Cat-floc, glycol chitosan, and methylglycol chitosan.

  13. Opposing effects of cationic antimicrobial peptides and divalent cations on bacterial lipopolysaccharides

    Science.gov (United States)

    Smart, Matthew; Rajagopal, Aruna; Liu, Wing-Ki; Ha, Bae-Yeun

    2017-10-01

    The permeability of the bacterial outer membrane, enclosing Gram-negative bacteria, depends on the interactions of the outer, lipopolysaccharide (LPS) layer, with surrounding ions and molecules. We present a coarse-grained model for describing how cationic amphiphilic molecules (e.g., antimicrobial peptides) interact with and perturb the LPS layer in a biologically relevant medium, containing monovalent and divalent salt ions (e.g., Mg2+). In our approach, peptide binding is driven by electrostatic and hydrophobic interactions and is assumed to expand the LPS layer, eventually priming it for disruption. Our results suggest that in parameter ranges of biological relevance (e.g., at micromolar concentrations) the antimicrobial peptide magainin 2 effectively disrupts the LPS layer, even though it has to compete with Mg2+ for the layer. They also show how the integrity of LPS is restored with an increasing concentration of Mg2+. Using the approach, we make a number of predictions relevant for optimizing peptide parameters against Gram-negative bacteria and for understanding bacterial strategies to develop resistance against cationic peptides.

  14. Chemical bonding and structural ordering of cations in silicate glasses

    International Nuclear Information System (INIS)

    Calas, G.; Cormier, L.; Galoisy, L.; Ramos, A.; Rossano, St.

    1997-01-01

    The specific surrounding of cations in multicomponent silicate glasses is briefly presented. Information about interatomic distances and site geometry may be gained by using spectroscopic methods among which x-ray absorption spectroscopy may be used for the largest number of glass components. Scattering of x-rays and neutrons may also be used to determine the importance of medium range order around specific cations. All the existing data show that cations occur in sites with a well-defined geometry, which are in most cases connected to the silicate polymeric network. Medium range order has been detected around cations such as Ti, Ca and Ni, indicating that these elements have an heterogeneous distribution within the glassy matrix. (authors)

  15. Dynamics of photoexcited Ba+ cations in 4He nanodroplets

    International Nuclear Information System (INIS)

    2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" >Leal, Antonio; 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain))" >Pi, Martí; Zhang, Xiaohang; Drabbels, Marcel; 2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France))" data-affiliation=" (Departament ECM, Facultat de Física, and IN2UB, Universitat de Barcelona, Diagonal 645, 08028 Barcelona (Spain); Laboratoire des Collisions, Agrégats, Réactivité, IRSAMC, UMR 5589, CNRS et Université Paul Sabatier-Toulouse 3, 118 route de Narbonne, F-31062 Toulouse Cedex 09 (France))" >Barranco, Manuel; Cargnoni, Fausto; Hernando, Alberto; Mateo, David; Mella, Massimo

    2016-01-01

    We present a joint experimental and theoretical study on the desolvation of Ba + cations in 4 He nanodroplets excited via the 6p ← 6s transition. The experiments reveal an efficient desolvation process yielding mainly bare Ba + cations and Ba + He n exciplexes with n = 1 and 2. The speed distributions of the ions are well described by Maxwell-Boltzmann distributions with temperatures ranging from 60 to 178 K depending on the excitation frequency and Ba + He n exciplex size. These results have been analyzed by calculations based on a time-dependent density functional description for the helium droplet combined with classical dynamics for the Ba + . In agreement with experiment, the calculations reveal the dynamical formation of exciplexes following excitation of the Ba + cation. In contrast to experimental observation, the calculations do not reveal desolvation of excited Ba + cations or exciplexes, even when relaxation pathways to lower lying states are included.

  16. Aggregation of trypsin and trypsin inhibitor by Al cation.

    Science.gov (United States)

    Chanphai, P; Kreplak, L; Tajmir-Riahi, H A

    2017-04-01

    Al cation may trigger protein structural changes such as aggregation and fibrillation, causing neurodegenerative diseases. We report the effect of Al cation on the solution structures of trypsin (try) and trypsin inhibitor (tryi), using thermodynamic analysis, UV-Visible, Fourier transform infrared (FTIR) spectroscopic methods and atomic force microscopy (AFM). Thermodynamic parameters showed Al-protein bindings occur via H-bonding and van der Waals contacts for trypsin and trypsin inhibitor. AFM showed that Al cations are able to force trypsin into larger or more robust aggregates than trypsin inhibitor, with trypsin 5±1 SE (n=52) proteins per aggregate and for trypsin inhibitor 8.3±0.7 SE (n=118). Thioflavin T test showed no major protein fibrillation in the presence of Al cation. Al complexation induced more alterations of trypsin inhibitor conformation than trypsin. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Significant role of cationic polymers in drug delivery systems.

    Science.gov (United States)

    Farshbaf, Masoud; Davaran, Soodabeh; Zarebkohan, Amir; Annabi, Nasim; Akbarzadeh, Abolfazl; Salehi, Roya

    2017-11-06

    Cationic polymers are characterized as the macromolecules that possess positive charges, which can be either inherently in the polymer side chains and/or its backbone. Based on their origins, cationic polymers are divided in two category including natural and synthetic, in which the possessed positive charges are as result of primary, secondary or tertiary amine functional groups that could be protonated in particular situations. Cationic polymers have been employed commonly as drug delivery agents due to their superior encapsulation efficacy, enhanced bioavailability, low toxicity and improved release profile. In this paper, we focus on the most prominent examples of cationic polymers which have been revealed to be applicable in drug delivery systems and we also discuss their general synthesis and surface modification methods as well as their controlled release profile in drug delivery.

  18. Changing certain dietary cationic and anionic minerals: Impact on ...

    African Journals Online (AJOL)

    Changing certain dietary cationic and anionic minerals: Impact on blood chemistry, milk ... Increased blood pH and serum HCO3 were noticed in buffaloes fed with LC ... Serum calcium and chloride increased with decreased DCAD level while ...

  19. Mercury release from deforested soils triggered by base cation enrichment

    International Nuclear Information System (INIS)

    Farella, N.; Lucotte, M.; Davidson, R.; Daigle, S.

    2006-01-01

    The Brazilian Amazon has experienced considerable colonization in the last few decades. Family agriculture based on slash-and-burn enables millions of people to live in that region. However, the poor nutrient content of most Amazonian soils requires cation-rich ashes from the burning of the vegetation biomass for cultivation to be successful, which leads to forest ecosystem degradation, soil erosion and mercury contamination. While recent studies have suggested that mercury present in soils was transferred towards rivers upon deforestation, little is known about the dynamics between agricultural land-use and mercury leaching. In this context, the present study proposes an explanation that illustrates how agricultural land-use triggers mercury loss from soils. This explanation lies in the competition between base cations and mercury in soils which are characterized by a low adsorption capacity. Since these soils are naturally very poor in base cations, the burning of the forest biomass suddenly brings high quantities of base cations to soils, destabilizing the previous equilibrium amongst cations. Base cation enrichment triggers mobility in soil cations, rapidly dislocating mercury atoms. This conclusion comes from principal component analyses illustrating that agricultural land-use was associated with base cation enrichment and mercury depletion. The overall conclusions highlight a pernicious cycle: while soil nutrient enrichment actually occurs through biomass burning, although on a temporary basis, there is a loss in Hg content, which is leached to rivers, entering the aquatic chain, and posing a potential health threat to local populations. Data presented here reflects three decades of deforestation activities, but little is known about the long-term impact of such a disequilibrium. These findings may have repercussions on our understanding of the complex dynamics of deforestation and agriculture worldwide

  20. Isomerizations of the Nitromethane Radical Cation in the Gas Phase

    DEFF Research Database (Denmark)

    Egsgaard, Helge; Carlsen, Lars; Elbel, Susanne

    1986-01-01

    The concurrent isomerizations of the nitromethane radical cation to its aci-nitromethane and methylnitrite isomers, respectively, has been established based on metastable ion studies and collision activation mass spectrometry. The energy diagram for the ionized nitromethane/aci-nitromethane tauto......The concurrent isomerizations of the nitromethane radical cation to its aci-nitromethane and methylnitrite isomers, respectively, has been established based on metastable ion studies and collision activation mass spectrometry. The energy diagram for the ionized nitromethane...

  1. Tunable states of interlayer cations in two-dimensional materials

    International Nuclear Information System (INIS)

    Sato, K.; Numata, K.; Dai, W.; Hunger, M.

    2014-01-01

    The local state of cations inside the Ångstrom-scale interlayer spaces is one of the controlling factors for designing sophisticated two-dimensional (2D) materials consisting of 2D nanosheets. In the present work, the molecular mechanism on how the interlayer cation states are induced by the local structures of the 2D nanosheets is highlighted. For this purpose, the local states of Na cations in inorganic 2D materials, in which the compositional fluctuations of a few percent are introduced in the tetrahedral and octahedral units of the 2D nanosheets, were systematically studied by means of 23 Na magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) and 23 Na multiple-quantum MAS (MQMAS) NMR spectroscopy. In contrast with an uniform distribution of Na cations expected so far, various well-defined cation states sensitive to the local structures of the 2D nanosheets were identified. The tunability of the interlayer cation states along with the local structure of the 2D nanosheets, as the smallest structural unit of the 2D material, is discussed

  2. Tunable states of interlayer cations in two-dimensional materials

    Energy Technology Data Exchange (ETDEWEB)

    Sato, K.; Numata, K. [Department of Environmental Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501 (Japan); Dai, W. [Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071 (China); Hunger, M. [Institute of Chemical Technology, University of Stuttgart, 70550 Stuttgart (Germany)

    2014-03-31

    The local state of cations inside the Ångstrom-scale interlayer spaces is one of the controlling factors for designing sophisticated two-dimensional (2D) materials consisting of 2D nanosheets. In the present work, the molecular mechanism on how the interlayer cation states are induced by the local structures of the 2D nanosheets is highlighted. For this purpose, the local states of Na cations in inorganic 2D materials, in which the compositional fluctuations of a few percent are introduced in the tetrahedral and octahedral units of the 2D nanosheets, were systematically studied by means of {sup 23}Na magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) and {sup 23}Na multiple-quantum MAS (MQMAS) NMR spectroscopy. In contrast with an uniform distribution of Na cations expected so far, various well-defined cation states sensitive to the local structures of the 2D nanosheets were identified. The tunability of the interlayer cation states along with the local structure of the 2D nanosheets, as the smallest structural unit of the 2D material, is discussed.

  3. Separation of cations of heavy metalsfrom concentrated galvanic drains

    Directory of Open Access Journals (Sweden)

    L. P. Bondareva

    2018-01-01

    Full Text Available When applying galvanic coatings, soluble salts of heavy metals such as iron, copper, nickel, zinc, cadmium, chromium and other metals are used, toxic cations enter the water, with subsequent migration to the biosphere. To date, many methods have been developed for cleaning galvanic sewage, which cannot be considered sufficiently effective. The joint sorption of divalent cations of copper, nickel and cadmium from concentrated aqueous solutions was investigated. Calculation and experimental methods were used to determine the separation conditions of the bivalent ion systems that differed and close in sorption properties on the aminophosphonic polyampholyte Purolite S950 in a natrium form. It is shown that the cadmium (II cations can be isolated from solutions containing copper (II or nickel (II cations even at the height of the sorption layer of 0.13 m due to the difference in the defining characteristics of the cations. This layer height can be used not only in a chromatographic column, but also in a concentrating cartridge. Separation of the copper (II and nickel (II close to the sorption properties requires an absorbing layer of 0.76 m, which can only be used in a chromatographic column, but not for a concentrating cartridge. In this paper, the degrees of ion separation in various sorption conditions are calculated. The applicability of the conductometric method for controlling the ion exchange process is shown not only when the free cations are isolated from aqueous solutions but also bound to complexes.

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

    Science.gov (United States)

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

    2015-04-02

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

  5. How the cation-cation π-π stacking occurs: A theoretical investigation into ionic clusters of imidazolium.

    Science.gov (United States)

    Gao, Wei; Tian, Yong; Xuan, Xiaopeng

    2015-07-01

    The cation-cation π-π stacking is uncommon but it is essential for the understanding of some supramolecular structures. We explore theoretically the nature of non-covalent interaction occurring in the stacked structure within modeled clusters of 1,3-dimethylimidazolium and halide. The evidences of the energy decomposition analysis (EDA) and reduced density gradient (RDG) approach are different from those of common π-π interaction. Isosurfaces with RDG also illustrate the strength of the titled π-π interaction and their region. Additionally, we find that the occurrence of this interaction is attributed to a few C-H···X interactions, as depicted using atom in molecule (AIM) method. This work presents a clear picture of the typical cation-cation π-π interaction and can serve to advance the understanding of this uncommon interaction. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Does the cation really matter? The effect of modifying an ionic liquid cation on an SN2 process.

    Science.gov (United States)

    Tanner, Eden E L; Yau, Hon Man; Hawker, Rebecca R; Croft, Anna K; Harper, Jason B

    2013-09-28

    The rate of reaction of a Menschutkin process in a range of ionic liquids with different cations was investigated, with temperature-dependent kinetic data giving access to activation parameters for the process in each solvent. These data, along with molecular dynamics simulations, demonstrate the importance of accessibility of the charged centre on the cation and that the key interactions are of a generalised electrostatic nature.

  7. Sorption of the organic cation metoprolol on silica gel from its aqueous solution considering the competition of inorganic cations.

    Science.gov (United States)

    Kutzner, Susann; Schaffer, Mario; Börnick, Hilmar; Licha, Tobias; Worch, Eckhard

    2014-05-01

    Systematic batch experiments with the organic monovalent cation metoprolol as sorbate and the synthetic material silica gel as sorbent were conducted with the aim of characterizing the sorption of organic cations onto charged surfaces. Sorption isotherms for metoprolol (>99% protonated in the tested pH of around 6) in competition with mono- and divalent inorganic cations (Na(+), NH4(+), Ca(2+), and Mg(2+)) were determined in order to assess their influence on cation exchange processes and to identify the role of further sorptive interactions. The obtained sorption isotherms could be described well by an exponential function (Freundlich isotherm model) with consistent exponents (about 0.8). In general, a decreasing sorption of metoprolol with increasing concentrations in inorganic cations was observed. Competing ions of the same valence showed similar effects. A significant sorption affinity of metoprolol with ion type dependent Freundlich coefficients KF,0.77 between 234.42 and 426.58 (L/kg)(0.77) could still be observed even at very high concentrations of competing inorganic cations. Additional column experiments confirm this behavior, which suggests the existence of further relevant interactions beside cation exchange. In subsequent batch experiments, the influence of mixtures with more than one competing ion and the effect of a reduced negative surface charge at a pH below the point of zero charge (pHPZC ≈ 2.5) were also investigated. Finally, the study demonstrates that cation exchange is the most relevant but not the sole mechanism for the sorption of metoprolol on silica gel. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Aspects of nonviral gene therapy: correlation of molecular parameters with lipoplex structure and transfection efficacy in pyridinium-based cationic lipids.

    Science.gov (United States)

    Parvizi, Paria; Jubeli, Emile; Raju, Liji; Khalique, Nada Abdul; Almeer, Ahmed; Allam, Hebatalla; Manaa, Maryem Al; Larsen, Helge; Nicholson, David; Pungente, Michael D; Fyles, Thomas M

    2014-01-30

    This study seeks correlations between the molecular structures of cationic and neutral lipids, the lipid phase behavior of the mixed-lipid lipoplexes they form with plasmid DNA, and the transfection efficacy of the lipoplexes. Synthetic cationic pyridinium lipids were co-formulated (1:1) with the cationic lipid 1,2-dimyristoyl-sn-glycero-3-ethylphosphocholine (EPC), and these lipids were co-formulated (3:2) with the neutral lipids 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE) or cholesterol. All lipoplex formulations exhibited plasmid DNA binding and a level of protection from DNase I degradation. Composition-dependent transfection (beta-galactosidase and GFP) and cytotoxicity was observed in Chinese hamster ovarian-K1 cells. The most active formulations containing the pyridinium lipids were less cytotoxic but of comparable activity to a Lipofectamine 2000™ control. Molecular structure parameters and partition coefficients were calculated for all lipids using fragment additive methods. The derived shape parameter values correctly correlated with observed hexagonal lipid phase behavior of lipoplexes as derived from small-angle X-ray scattering experiments. A transfection index applicable to hexagonal phase lipoplexes derived from calculated parameters of the lipid mixture (partition coefficient, shape parameter, lipoplex packing) produced a direct correlation with transfection efficiency. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. High-capacity cation-exchange column for enhanced resolution of adjacent peaks of cations in ion chromatography.

    Science.gov (United States)

    Rey, M A

    2001-06-22

    One of the advantages of ion chromatography [Anal Chem. 47 (1975) 1801] as compared to other analytical techniques is that several ions may be analyzed simultaneously. One of the most important contributions of cation-exchange chromatography is its sensitivity to ammonium ion, which is difficult to analyze by other techniques [J. Weiss, in: E.L. Johnson (Ed.), Handbook of Ion Chromatography, Dionex, Sunnyvale, CA, USA]. The determination of low concentrations of ammonium ion in the presence of high concentrations of sodium poses a challenge in cation-exchange chromatography [J. Weiss, Ion Chromatography, VCH, 2nd Edition, Weinheim, 1995], as both cations have similar selectivities for the common stationary phases containing either sulfonate or carboxylate functional groups. The task was to develop a new cation-exchange stationary phase (for diverse concentration ratios of adjacent peaks) to overcome limitations experienced in previous trails. Various cation-exchange capacities and column body formats were investigated to optimize this application and others. The advantages and disadvantages of two carboxylic acid columns of different cation-exchange capacities and different column formats will be discussed.

  10. Serbia's Military Neutrality: Origins, effects and challenges

    Directory of Open Access Journals (Sweden)

    Ejdus Filip

    2014-10-01

    Full Text Available Serbia is the only state in the Western Balkans that is not seeking NATO membership. In December 2007, Serbia declared military neutrality and in spite of its EU membership aspirations, developed very close relations with Moscow. The objective of this paper is threefold. First, I argue that in order to understand why Serbia declared military neutrality, one has to look both at the discursive terrain and domestic power struggles. The key narrative that was strategically used by mnemonic entrepreneurs, most importantly by the former Prime Minister Vojislav Koštunica, to legitimize military neutrality was the trauma of NATO intervention in 1999 and the ensuing secession of Kosovo. In the second part of the paper, I discuss the operational consequences of the military neutrality policy for Serbia's relations with NATO and Russia, as well as for military reform and EU accession. Finally, I spell out the challenges ahead in Serbia's neutrality policy and argue that its decision makers will increasingly be caught between pragmatic foreign policy requirements on the one hand and deeply entrenched traumatic memories on the other.

  11. Kinetic Properties of the Neutral Solar Wind

    International Nuclear Information System (INIS)

    Florinski, V.; Heerikhuisen, J.

    2017-01-01

    Charge-exchange collisions between the solar wind protons and interstellar hydrogen produce a distinctive population of neutral hydrogen streaming radially at nearly the solar-wind speed. This tenuous population, known as the neutral solar wind (NSW) is thought to play a key role in the appearance of the Interplanetary Boundary EXplorer ribbon, a bright circular band in the sky that is the source of neutral hydrogen with energies near 1 keV. According to the leading model of the ribbon, the velocity distribution of NSW hydrogen is imparted on the pickup ions (PUIs) generated via charge exchange with the interstellar protons beyond the heliopause, and in this way controls the stability of the resulting ring distribution of PUIs against hydromagnetic wave generation. In this paper, we examine the velocity distributions of the NSW atoms in the heliosphere and the outer heliosheath regions by following the phase-space trajectories of the Boltzmann equation. It is demonstrated that these distributions are highly anisotropic, with the parallel (radial) temperature greatly exceeding the perpendicular temperature. Ions picked up near 90° from the anisotropic NSW would form a stable ring distribution capable of generating the ribbon flux. We also discuss a second population of neutrals born in charge transfer collisions with interstellar PUIs, the so-called neutralized pickup ion (NPI) component. Their high thermal velocities translate into large parallel velocity spread of the daughter ribbon PUIs, which would adversely affect plasma stability in local interstellar space.

  12. Kinetic Properties of the Neutral Solar Wind

    Science.gov (United States)

    Florinski, V.; Heerikhuisen, J.

    2017-03-01

    Charge-exchange collisions between the solar wind protons and interstellar hydrogen produce a distinctive population of neutral hydrogen streaming radially at nearly the solar-wind speed. This tenuous population, known as the neutral solar wind (NSW) is thought to play a key role in the appearance of the Interplanetary Boundary EXplorer ribbon, a bright circular band in the sky that is the source of neutral hydrogen with energies near 1 keV. According to the leading model of the ribbon, the velocity distribution of NSW hydrogen is imparted on the pickup ions (PUIs) generated via charge exchange with the interstellar protons beyond the heliopause, and in this way controls the stability of the resulting ring distribution of PUIs against hydromagnetic wave generation. In this paper, we examine the velocity distributions of the NSW atoms in the heliosphere and the outer heliosheath regions by following the phase-space trajectories of the Boltzmann equation. It is demonstrated that these distributions are highly anisotropic, with the parallel (radial) temperature greatly exceeding the perpendicular temperature. Ions picked up near 90° from the anisotropic NSW would form a stable ring distribution capable of generating the ribbon flux. We also discuss a second population of neutrals born in charge transfer collisions with interstellar PUIs, the so-called neutralized pickup ion (NPI) component. Their high thermal velocities translate into large parallel velocity spread of the daughter ribbon PUIs, which would adversely affect plasma stability in local interstellar space.

  13. Neutral axis as damage sensitive feature

    International Nuclear Information System (INIS)

    Sigurdardottir, D H; Glisic, B

    2013-01-01

    Structural health monitoring (SHM) is the process of continuously or periodically measuring structural parameters and the transformation of the collected data into information on real structural conditions. The centroid of stiffness is a universal parameter and its position in a cross-section can be evaluated for any load-carrying beam structure as the position of the neutral axis under conveniently chosen loads. Thus, a change in the position of the neutral axis within a cross-section can indicate a change in the position of the centroid of stiffness, i.e., unusual structural behaviors. This paper proposes a novel monitoring method based on deterministic and probabilistic determination of the position of the neutral axis under conveniently chosen conditions. Therefore, the method proposed in this paper is potentially applicable to a large variety of beam-like structures. Data from two existing structures were used to validate the method and assess its performance: Streicker Bridge at Princeton University and the US202/NJ23 highway overpass in Wayne, NJ. The results show that the neutral axis location is varying even when damage is not present. Reasons for this variation are determined and the accuracy in the evaluation assessed. This paper concludes that the position of the neutral axis can be evaluated with sufficient accuracy using static and dynamic strain measurements performed on appropriate time-scales and indicates its potential to be used as a damage sensitive feature. (paper)

  14. Neutral axis as damage sensitive feature

    Science.gov (United States)

    Sigurdardottir, D. H.; Glisic, B.

    2013-07-01

    Structural health monitoring (SHM) is the process of continuously or periodically measuring structural parameters and the transformation of the collected data into information on real structural conditions. The centroid of stiffness is a universal parameter and its position in a cross-section can be evaluated for any load-carrying beam structure as the position of the neutral axis under conveniently chosen loads. Thus, a change in the position of the neutral axis within a cross-section can indicate a change in the position of the centroid of stiffness, i.e., unusual structural behaviors. This paper proposes a novel monitoring method based on deterministic and probabilistic determination of the position of the neutral axis under conveniently chosen conditions. Therefore, the method proposed in this paper is potentially applicable to a large variety of beam-like structures. Data from two existing structures were used to validate the method and assess its performance: Streicker Bridge at Princeton University and the US202/NJ23 highway overpass in Wayne, NJ. The results show that the neutral axis location is varying even when damage is not present. Reasons for this variation are determined and the accuracy in the evaluation assessed. This paper concludes that the position of the neutral axis can be evaluated with sufficient accuracy using static and dynamic strain measurements performed on appropriate time-scales and indicates its potential to be used as a damage sensitive feature.

  15. A Measurement of Coherent Neutral Pion Production in Neutrino Neutral Current Interactions in NOMAD experiment

    CERN Document Server

    Kullenberg, C T

    2009-01-01

    We present a study of exclusive neutral pion production in neutrino-nucleus Neutral Current interactions using data from the NOMAD experiment at the CERN SPS. The data correspond to $1.44 \\times 10^6$ muon-neutrino Charged Current interactions in the energy range $2.5 \\leq E_{\

  16. The control of powerful neutral beams

    International Nuclear Information System (INIS)

    Theil, E.; Jacobson, V.

    1986-01-01

    While significant progress has been made in the development of neutral beams for the heating and sustaining of plasmas in large fusion experiments, the control of such devices has largely been a matter of hardware interlocks and operator experience. The need for computer-assisted control becomes more evident, however, with the initiation of multi-beamline experiments. This paper describes a software system that incorporates simple mathematical models coupled to Kalman filters for control of the high power (6 to 8 MW) beams currently under development at Lawrence Berkeley Laboratory's Neutral Beam Engineering Test Facility. Among the principal features of the system are: reduction of a large number of operator variables to just a few (usually one or two); the ability to describe most of the major neutral beams in use and under development; a foundation resting on statistical data analysis and control system principles rather than rules-of-thumb

  17. Neutralization kinetics of charged polymer surface

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, S. [Surface Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India); Mukherjee, M. [Surface Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India)], E-mail: manabendra.mukherjee@saha.ac.in

    2008-04-15

    In case of photoemission spectroscopy of an insulating material the data obtained from the charged surface are normally distorted due to differential charging. Recently, we have developed a controlled surface neutralization technique to study the kinetics of the surface charging. Using this technique and the associated data analysis scheme with an effective charging model, quantitative information from the apparently distorted photoemission data from PTFE surfaces were extracted. The surface charging was controlled by tuning the electron flood current as well as the X-ray intensity. The effective model was found to describe the charging consistently for both the cases. It was shown that the non-linear neutralization response of differential charging around a critical neutralizing electron flux or a critical X-ray emission current was due to percolation of equipotential surface domains. The obtained value of the critical percolation exponent {gamma} close to unity indicates a percolation similar to that of avalanche breakdown or chain reaction.

  18. The Framing of Network Neutrality Governance

    DEFF Research Database (Denmark)

    Perry, James

    The neutrality of the internet with regard to applications (e.g. search, social networking, email, to mention only three) has been central to innovation and growth in the knowledge-economy over the past two decades. Until recently, neutrality was built into the internet's design via its core stan...... with a critical analysis of their respective operational paradigms, the paper seeks to understand who is framing the debate, how they are doing so, and to what (systemic) effect....... generative: Useful innovations in applications of the internet could take hold easily, and it was difficult – or indeed impossible - for incumbent business interests to disrupt or sabotage them. However, this neutrality is now under threat. New technologies have given incumbent businesses the ability...

  19. Current neutralization of converging ion beams

    International Nuclear Information System (INIS)

    Mosher, D.

    1978-01-01

    It is desired to consider the problem of current neutralization of heavy ion beams traversing gas backgrounds in which the conductivity changes due to beam heating and beam convergence. The procedure is to determine Green's-function solutions to the magnetic-diffusion equation derived from Maxwell's equations and an assumed scaler-plasma conductivity sigma for the background-electron current density j/sub e/. The present calculation is more general than some previously carried out in that arbitrary time variations for the beam current j/sub b/ and conductivity are allowed and the calculation is valid for both weak and strong neutralization. Results presented here must be combined with an appropriate energy-balance equation for the heated background in order to obtain the neutralization self-consistently

  20. Optimal neutral beam heating scenario for FED

    International Nuclear Information System (INIS)

    Hively, L.M.; Houlberg, W.A.; Attenberger, S.E.

    1981-01-01

    Optimal neutral beam heating scenarios are determined for FED based on a 1/one-half/-D transport analysis. Tradeoffs are examined between neutral beam energy, power, and species mix for positive ion systems. A ramped density startup is found to provide the most economical heating. The resulting plasma power requirements are reduced by 10-30% from a constant density startup. For beam energies between 100 and 200 keV, the power needed to heat the plasma does not decrease significantly as beam energy is increased. This is due to reduced ion heating, more power in the fractional energy components, and rising power supply requirements as beam energy increases

  1. Inducing Risk Neutral Preferences with Binary Lotteries

    DEFF Research Database (Denmark)

    Harrison, Glenn W.; Martínez-Correa, Jimmy; Swarthout, J. Todd

    2013-01-01

    validity of any strategic equilibrium behavior, or even the customary independence axiom. We show that subjects sampled from our population are generally risk averse when lotteries are defined over monetary outcomes, and that the binary lottery procedure does indeed induce a statistically significant shift......We evaluate the binary lottery procedure for inducing risk neutral behavior. We strip the experimental implementation down to bare bones, taking care to avoid any potentially confounding assumptions about behavior having to be made. In particular, our evaluation does not rely on the assumed...... toward risk neutrality. This striking result generalizes to the case in which subjects make several lottery choices and one is selected for payment....

  2. Beam divergence scaling in neutral beam injectors

    International Nuclear Information System (INIS)

    Holmes, A.J.T.

    1976-01-01

    One of the main considerations in the design of neutral beam injectors is to monimize the divergence of the primary ion beam and hence maximize the beam transport and minimize the input of thermal gas. Experimental measurements of the divergence of a cylindrical ion beam are presented and these measurements are used to analyze the major components of ion beam divergence, namely: space charge expansion, gas-ion scattering, emittance and optical aberrations. The implication of these divergence components in the design of a neutral beam injector system is discussed and a method of maximizing the beam current is described for a given area of source plasma

  3. Simplified Stability Criteria for Delayed Neutral Systems

    Directory of Open Access Journals (Sweden)

    Xinghua Zhang

    2014-01-01

    Full Text Available For a class of linear time-invariant neutral systems with neutral and discrete constant delays, several existing asymptotic stability criteria in the form of linear matrix inequalities (LMIs are simplified by using matrix analysis techniques. Compared with the original stability criteria, the simplified ones include fewer LMI variables, which can obviously reduce computational complexity. Simultaneously, it is theoretically shown that the simplified stability criteria and original ones are equivalent; that is, they have the same conservativeness. Finally, a numerical example is employed to verify the theoretic results investigated in this paper.

  4. Neutral Naturalness from Orbifold Higgs Models

    Science.gov (United States)

    Craig, Nathaniel; Knapen, Simon; Longhi, Pietro

    2015-02-01

    We present a general class of natural theories in which the Higgs boson is a pseudo-Goldstone boson in an orbifolded gauge theory. The symmetry protecting the Higgs boson at low energies is an accidental global symmetry of the quadratic action, rather than a full continuous symmetry. The lightest degrees of freedom protecting the weak scale carry no standard model (SM) quantum numbers and interact with visible matter principally through the Higgs portal. This opens the door to the systematic study of "neutral naturalness": natural theories with SM-neutral states that are as yet untested by the LHC.

  5. Greenhouse gas neutral Germany in 2050

    International Nuclear Information System (INIS)

    Benndorf, Rosemarie; Bernicke, Maja; Bertram, Andreas

    2014-01-01

    In order to answer the question how a greenhouse gas neutral Germany would look like an interdisciplinary process was started by the Federal Environmental Agency. It was clear from the beginning of this work that a sustainable regenerative energy supply could not be sufficient. Therefore all relevant emission sources were included into the studies: traffic, industry, waste and waste water, agriculture, land usage, land usage changes and forestry. The necessary transformation paths to reach the aim of a greenhouse gas neutral Germany in 2050, economic considerations and political instruments were not part of this study.

  6. PDX neutral-beam reionization losses

    International Nuclear Information System (INIS)

    Kugel, H.W.; Dylla, H.F.; Eubank, H.P.; Kozub, T.A.; Moore, R.; Schilling, G.; Stewart, L.D.; von Halle, A.; Williams, M.D.

    1982-02-01

    Reionization losses for 1.5 MW H 0 and 2 MW D 0 neutral beams injected into the PDX tokamak were studied using pressure gauges, photo-transistors, thermocouples, surface shielding, and surface sample analysis. Considerable outgassing of conventionally prepared 304SS ducts occurred during initial injections and gradually decreased with the cumulative absorption of beam power. Reionization power losses are presently about 5% in the ducts and about 12% total for a beamline including the duct. Present duct pressures are attributed primarily to gas from the ion source and neutralizer with much smaller contributions from residual wall desorption. Physical mechanisms for the observed duct outgassing are discussed

  7. Neutral beam injection in 2XIIB

    International Nuclear Information System (INIS)

    Hibbs, S.M.

    1975-01-01

    Integrated into the operation of the 2XIIB controlled fusion experiment is a 600-A, 20-keV neutral injection system: the highest neutral-beam current capacity of any existing fusion machine. This paper outlines the requirements of the injection system and the design features to which they led. Both mechanical and electrical aspects are discussed. Also included is a brief description of some operational aspects of the system and some of the things we have learned along the way, as well as a short history of the most significant developments

  8. The net neutrality debate on Twitter

    Directory of Open Access Journals (Sweden)

    Wolf J. Schünemann

    2015-12-01

    Full Text Available The internet has been seen as a medium that empowers individual political actors in relation to established political elites and media gatekeepers. The present article discusses this “net empowerment hypothesis” and tests it empirically by analysing Twitter communication on the regulation of net neutrality. We extracted 503.839 tweets containing #NetNeutrality posted between January and March 2015 and analysed central developments and the network structure of the debate. The empirical results show that traditional actors from media and politics still maintain a central role.

  9. Specific lysosomal transport of small neutral amino acids

    International Nuclear Information System (INIS)

    Pisoni, R.L.; Flickinger, K.S.; Thoene, J.G.; Christensen, H.N.

    1986-01-01

    Studies of amino acid exodus from lysosomes have allowed us previously to describe transport systems specific for cystine and another for cationic amino acids in fibroblast lysosomes. They are now able to study amino acid uptake into highly purified fibroblast lysosomes obtained by separating crude granular fraction on gradients formed by centrifugation in 35% isoosmotic Percoll solutions. Analog inhibition and saturation studies indicate that L-[ 14 C]proline (50 μM) uptake by fibroblast lysosomes at 37 0 C in 50 mM citrate/tris pH 7.0 buffer containing 0.25 M sucrose is mediated by two transport systems, one largely specific for L-proline and the other for which transport is shared with small neutral amino acids such as alanine, serine and threonine. At 7 mM, L-proline inhibits L-[ 14 C]proline uptake almost completely, whereas ala, ser, val, thr, gly, N-methylalanine and sarcosine inhibit proline uptake by 50-65%. The system shared by alanine, serine and threonine is further characterized by these amino acids strongly inhibiting the uptakes of each other. Lysosomal proline transport is selective for the L-isomer of the amino acid, and is scarcely inhibited by 7 mM arg, glu, asp, leu, phe, his, met, (methylamino) isobutyrate, betaine or N,N-dimethylglycine. Cis or trans-4-hydroxy-L-proline inhibit proline uptake only slightly. In sharp contrast to the fibroblast plasma membrane in which Na + is required for most proline and alanine transport, lysosomal uptake of these amino acids occurs independently of Na +

  10. Cation Substitution in Earth‐Abundant Kesterite Photovoltaic Materials

    Science.gov (United States)

    Li, Jianjun; Wang, Dongxiao; Li, Xiuling; Zeng, Yu

    2018-01-01

    Abstract As a promising candidate for low‐cost and environmentally friendly thin‐film photovoltaics, the emerging kesterite‐based Cu2ZnSn(S,Se)4 (CZTSSe) solar cells have experienced rapid advances over the past decade. However, the record efficiency of CZTSSe solar cells (12.6%) is still significantly lower than those of its predecessors Cu(In,Ga)Se2 (CIGS) and CdTe thin‐film solar cells. This record has remained for several years. The main obstacle for this stagnation is unanimously attributed to the large open‐circuit voltage (V OC) deficit. In addition to cation disordering and the associated band tailing, unpassivated interface defects and undesirable energy band alignment are two other culprits that account for the large V OC deficit in kesterite solar cells. To capture the great potential of kesterite solar cells as prospective earth‐abundant photovoltaic technology, current research focuses on cation substitution for CZTSSe‐based materials. The aim here is to examine recent efforts to overcome the V OC limit of kesterite solar cells by cation substitution and to further illuminate several emerging prospective strategies, including: i) suppressing the cation disordering by distant isoelectronic cation substitution, ii) optimizing the junction band alignment and constructing a graded bandgap in absorber, and iii) engineering the interface defects and enhancing the junction band bending. PMID:29721421

  11. Cation Substitution in Earth-Abundant Kesterite Photovoltaic Materials.

    Science.gov (United States)

    Li, Jianjun; Wang, Dongxiao; Li, Xiuling; Zeng, Yu; Zhang, Yi

    2018-04-01

    As a promising candidate for low-cost and environmentally friendly thin-film photovoltaics, the emerging kesterite-based Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells have experienced rapid advances over the past decade. However, the record efficiency of CZTSSe solar cells (12.6%) is still significantly lower than those of its predecessors Cu(In,Ga)Se 2 (CIGS) and CdTe thin-film solar cells. This record has remained for several years. The main obstacle for this stagnation is unanimously attributed to the large open-circuit voltage ( V OC ) deficit. In addition to cation disordering and the associated band tailing, unpassivated interface defects and undesirable energy band alignment are two other culprits that account for the large V OC deficit in kesterite solar cells. To capture the great potential of kesterite solar cells as prospective earth-abundant photovoltaic technology, current research focuses on cation substitution for CZTSSe-based materials. The aim here is to examine recent efforts to overcome the V OC limit of kesterite solar cells by cation substitution and to further illuminate several emerging prospective strategies, including: i) suppressing the cation disordering by distant isoelectronic cation substitution, ii) optimizing the junction band alignment and constructing a graded bandgap in absorber, and iii) engineering the interface defects and enhancing the junction band bending.

  12. THERMODYNAMICS OF ETHANOLAMMONIUM CATIONES DISSOCIATION IN AQUEOUS SOLUTIONS

    Directory of Open Access Journals (Sweden)

    R. E. Khoma

    2017-03-01

    Full Text Available The literature data on the thermodynamics of ethanolamines onium cations dissociation have been systematized and generalized. The correlation between these cations dissociation thermodynamic functions (DH and DS and physicochemical properties (Tmp., Tbp, Pp, lgPow et al. has been revealed. There was a correlation between lipophilicity determined experimentally and calculated by QSAR. For monoethanolammonium, diethanolammonium, and their N-methyl and N-ethyl derivatives it was found dissociation thermodynamic functions to depend on bases lgPow. Acid-base dissociation of TRIS and triethanolamine onium cations does not correspond to said relationship because TRIS (primary amine, TEA (tertiary amine act differently on aqueous solutions of SO2. TEA, unlike MEA, DEA and MMEA, has a salting out effect towards sulfur dioxide because of competing hydration that promotes sulfite «onium» salts hydrolysis. TRIS promotes S(IV → S(VI sulphooxidation, in contrast to another ethanolamines. Enthalpy–enthropy compensation with isothermodynamic temperature 303 K has been recorded. The revealed correlations may be useful in developing of procedures for air sanitary cleaning from acidic gases; chemisorbents immobilized for gas and ion exchange chromatography; potentiometric methods for fluorocomplex acids determinations. The use of monoethanolamine is most promising to obtain chemisorbents because the thermodynamic functions of its onium cation acid-base dissociation are least dependent on temperature compared to other etanolammonium cations.

  13. Cation-enhanced capillary electrophoresis separation of atropoisomer anions.

    Science.gov (United States)

    Na, Yun-Cheol; Berthod, Alain; Armstrong, Daniel W

    2015-12-01

    CE was used to study the separation of the atropoisomers of four phosphoric acids and two sulfonic acids and the enantiomers of two phosphoric acids. All solutes are in their anionic forms in aqueous electrolytes. The chiral additives were two hydroxypropyl cyclodextrins (CDs) and cyclofructan 6 (CF6). The CDs were able to separate four solutes and the CF6 additive could separate only one: 1,1'-binaphthyl-2,2'-diyl hydrogenphosphate (BHP). Since CF6 is able to bind with cations, nitrate of alkaline metals, Ba(2+) , and Pb(2+) were added, greatly improving the BHP separation at the expense of longer migration times. There seems to be a link between CF6-cation-binding constants and BHP resolution factors. Cation additions were also performed with CD selectors that are less prone to form complexes with cations. Significant improvements of enantiomer or atropoisomer separations were observed also associated with longer migration times. It is speculated that the anionic solutes associate with the added cations forming larger entities better differentiated by CDs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Cation Binding to Xanthorhodopsin: Electron Paramagnetic Resonance and Magnetic Studies.

    Science.gov (United States)

    Smolensky Koganov, Elena; Leitus, Gregory; Rozin, Rinat; Weiner, Lev; Friedman, Noga; Sheves, Mordechai

    2017-05-04

    Xanthorhodopsin (xR) is a member of the retinal protein family and acts as a proton pump in the cell membranes of the extremely halophilic eubacterium Salinibacter ruber. In addition to the retinal chromophore, xR contains a carotenoid, which acts as a light-harvesting antenna as it transfers 40% of the quanta it absorbs to the retinal. Our previous studies have shown that the CD and absorption spectra of xR are dramatically affected due to the protonation of two different residues. It is still unclear whether xR can bind cations. Electron paramagnetic resonance (EPR) spectroscopy used in the present study revealed that xR can bind divalent cations, such as Mn 2+ and Ca 2+ , to deionized xR (DI-xR). We also demonstrate that xR can bind 1 equiv of Mn 2+ to a high-affinity binding site followed by binding of ∼40 equiv in cooperative manner and ∼100 equiv of Mn 2+ that are weakly bound. SQUID magnetic studies suggest that the high cooperative binding of Mn 2+ cations to xR is due to the formation of Mn 2+ clusters. Our data demonstrate that Ca 2+ cations bind to DI-xR with a lower affinity than Mn 2+ , supporting the assumption that binding of Mn 2+ occurs through cluster formation, because Ca 2+ cations cannot form clusters in contrast to Mn 2+ .

  15. Cationic uremic toxins affect human renal proximal tubule cell functioning through interaction with the organic cation transporter.

    Science.gov (United States)

    Schophuizen, Carolien M S; Wilmer, Martijn J; Jansen, Jitske; Gustavsson, Lena; Hilgendorf, Constanze; Hoenderop, Joost G J; van den Heuvel, Lambert P; Masereeuw, Rosalinde

    2013-12-01

    Several organic cations, such as guanidino compounds and polyamines, have been found to accumulate in plasma of patients with kidney failure due to inadequate renal clearance. Here, we studied the interaction of cationic uremic toxins with renal organic cation transport in a conditionally immortalized human proximal tubule epithelial cell line (ciPTEC). Transporter activity was measured and validated in cell suspensions by studying uptake of the fluorescent substrate 4-(4-(dimethylamino)styryl)-N-methylpyridinium-iodide (ASP(+)). Subsequently, the inhibitory potencies of the cationic uremic toxins, cadaverine, putrescine, spermine and spermidine (polyamines), acrolein (polyamine breakdown product), guanidine, and methylguanidine (guanidino compounds) were determined. Concentration-dependent inhibition of ASP(+) uptake by TPA, cimetidine, quinidine, and metformin confirmed functional endogenous organic cation transporter 2 (OCT2) expression in ciPTEC. All uremic toxins tested inhibited ASP(+) uptake, of which acrolein required the lowest concentration to provoke a half-maximal inhibition (IC50 = 44 ± 2 μM). A Dixon plot was constructed for acrolein using three independent inhibition curves with 10, 20, or 30 μM ASP(+), which demonstrated competitive or mixed type of interaction (K i = 93 ± 16 μM). Exposing the cells to a mixture of cationic uremic toxins resulted in a more potent and biphasic inhibitory response curve, indicating complex interactions between the toxins and ASP(+) uptake. In conclusion, ciPTEC proves a suitable model to study cationic xenobiotic interactions. Inhibition of cellular uptake transport was demonstrated for several uremic toxins, which might indicate a possible role in kidney disease progression during uremia.

  16. Hydration of cations: a key to understanding of specific cation effects on aggregation behaviors of PEO-PPO-PEO triblock copolymers.

    Science.gov (United States)

    Lutter, Jacob C; Wu, Tsung-yu; Zhang, Yanjie

    2013-09-05

    This work reports results from the interactions of a series of monovalent and divalent cations with a triblock copolymer, poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO). Phase transition temperatures of the polymer in the presence of chloride salts with six monovalent and eight divalent cations were measured using an automated melting point apparatus. The polymer undergoes a two-step phase transition, consisting of micellization of the polymer followed by aggregation of the micelles, in the presence of all the salts studied herein. The results suggest that hydration of cations plays a key role in determining the interactions between the cations and the polymer. The modulation of the phase transition temperature of the polymer by cations can be explained as a balance between three interactions: direct binding of cations to the oxygen in the polymer chains, cations sharing one water molecule with the polymer in their hydration layer, and cations interacting with the polymer via two water molecules. Monovalent cations Na(+), K(+), Rb(+), and Cs(+) do not bind to the polymer, while Li(+) and NH4(+) and all the divalent cations investigated including Mg(2+), Ca(2+), Sr(2+), Ba(2+), Co(2+), Ni(2+), Cu(2+), and Cd(2+) bind to the polymer. The effects of the cations correlate well with their hydration thermodynamic properties. Mechanisms for cation-polymer interactions are discussed.

  17. Derivatives of Rhodamine 19 as Mild Mitochondria-targeted Cationic Uncouplers*

    Science.gov (United States)

    Antonenko, Yuri N.; Avetisyan, Armine V.; Cherepanov, Dmitry A.; Knorre, Dmitry A.; Korshunova, Galina A.; Markova, Olga V.; Ojovan, Silvia M.; Perevoshchikova, Irina V.; Pustovidko, Antonina V.; Rokitskaya, Tatyana I.; Severina, Inna I.; Simonyan, Ruben A.; Smirnova, Ekaterina A.; Sobko, Alexander A.; Sumbatyan, Natalia V.; Severin, Fedor F.; Skulachev, Vladimir P.

    2011-01-01

    A limited decrease in mitochondrial membrane potential can be beneficial for cells, especially under some pathological conditions, suggesting that mild uncouplers (protonophores) causing such an effect are promising candidates for therapeutic uses. The great majority of protonophores are weak acids capable of permeating across membranes in their neutral and anionic forms. In the present study, protonophorous activity of a series of derivatives of cationic rhodamine 19, including dodecylrhodamine (C12R1) and its conjugate with plastoquinone (SkQR1), was revealed using a variety of assays. Derivatives of rhodamine B, lacking dissociable protons, showed no protonophorous properties. In planar bilayer lipid membranes, separating two compartments differing in pH, diffusion potential of H+ ions was generated in the presence of C12R1 and SkQR1. These compounds induced pH equilibration in liposomes loaded with the pH probe pyranine. C12R1 and SkQR1 partially stimulated respiration of rat liver mitochondria in State 4 and decreased their membrane potential. Also, C12R1 partially stimulated respiration of yeast cells but, unlike the anionic protonophore FCCP, did not suppress their growth. Loss of function of mitochondrial DNA in yeast (grande-petite transformation) is known to cause a major decrease in the mitochondrial membrane potential. We found that petite yeast cells are relatively more sensitive to the anionic uncouplers than to C12R1 compared with grande cells. Together, our data suggest that rhodamine 19-based cationic protonophores are self-limiting; their uncoupling activity is maximal at high membrane potential, but the activity decreases membrane potentials, which causes partial efflux of the uncouplers from mitochondria and, hence, prevents further membrane potential decrease. PMID:21454507

  18. Radical cations in radiation chemistry of aldehydes. ESR study and quantum chemical analysis

    International Nuclear Information System (INIS)

    Belevskii, V.N.; Tyurin, D.A.; Chuvilkin, N.D.

    1998-01-01

    Quantum-chemical (MNDO-UHF) calculations of electronic, spin and energy characteristics of radical cations (RC) of ethanal, propanal, butanal, and pentanal and their distonic isomers were performed. The calculations both with 'frozen' (vertical ionization) and completely optimize geometry (adiabatic approximation) were made. It was been shown that the most positive charge and spin population are localized at O atoms and adjacent C atom as well as at aldehyde protons. The C-H bonds corresponding to those protons as well as neighboring C-O and C-C bonds are considerable weaker (longer) in radical cations as compared to their neutral precursors. That is why such reaction centers are apt to deprotonation with the formation of acyl radical as well as to α- and β-splitting (scission) which are well-known from aldehydes mass-spectra. Our calculations shown that distonic RC (products of intramolecular H-atom transfer) are more stable as compare to their classical isomers: e.g. the difference in energy ΔE = -0.95 eV, -1.2 eV, and -1.5 eV for tree distonic isomers of butanal RC as compare to classical isomer, ΔE -1.2 eV for distonic RC of ethanal. The results of calculations are effectively correlated with ESR data obtained in freonic solutions, X- and gamma-irradiated at 77 K and in liquid aldehydes, X-irradiated by using 2,4,6-tri-tert-burylnitrosobenzene (BNB) and t-BuNO (NtB) as a spin traps. (author)

  19. Synthesis of a Cationic Polyacrylamide under UV Initiation and Its Flocculation in Estrone Removal

    Directory of Open Access Journals (Sweden)

    Jiaoxia Sun

    2018-01-01

    Full Text Available A ternary cationic polyacrylamide (CPAM with the hydrophobic characteristic was prepared through ultraviolet- (UV- initiated polymerization technique for the estrone (E1 environmental estrogen separation and removal. The monomers of acrylamide (AM, acryloyloxyethyl-trimethyl ammonium chloride (DAC, and acryloyloxyethyl dimethylbenzyl ammonium chloride (AODBAC were used to synthesize the ternary copolymer (PADA. Fourier transform infrared spectroscopy (FT-IR, 1H nuclear magnetic resonance spectroscopy (1H NMR, thermogravimetry/differential scanning calorimetry (TG/DSC, and scanning electron microscopy (SEM were employed to characterize the structure, thermal decomposition property, and morphology of the polymers, respectively. FT-IR and 1H NMR results indicated the successful formation of the polymers. Besides, with the introduction of hydrophobic groups (phenyl group, an irregular and porous surface morphology and a favorable thermal stability of the PADA were observed by SEM and TG/DSC analyses, respectively. At the optimal condition (pH = 7, flocculant dosage = 4.0 mg/L and E1 concentration = 0.75 mg/L, an excellent E1 flocculation performance (E1 removal rate: 90.1%, floc size: 18.3 μm, and flocculation kinetics: 22.69×10-4 s−1 was acquired by using the efficient flocculant PADA-3 (cationic degree = 40%, and intrinsic viscosity = 6.30 dL·g−1. The zeta potential and floc size analyses were used to analyze the possible flocculation mechanism for the E1 removal. Results indicated that the charge neutralization, adsorption, and birding effects were dominant in the E1 removal progress.

  20. First observations of partially neutralized and quasineutral plasmas in the Columbia Non-neutral Torus

    Science.gov (United States)

    Sarasola, Xabier; Brenner, Paul; Hahn, Michael; Pedersen, Thomas

    2009-11-01

    The Columbia Non-neutral Torus (CNT) is the first stellarator devoted to the study of pure electron, partially neutralized and positron-electron plasmas. To date, CNT usually operates with electron rich plasmas (with negligible ion density) [1], but a stellarator can also confine plasmas of arbitrary degree of neutralization. In CNT the accumulation of ions alters the equilibrium of electron plasmas and a global instability has been observed when the ion fraction exceeds 10 %. A characterization of this instability is presented in [2], analyzing its parameter dependence and spatial structure (non- resonant with rational surfaces). A new set of experiments is currently underway studying plasmas of arbitrary degree of neutralization, ranging from pure electron to quasineutral plasmas. Basic observations show that the plasma potential decouples from emitter bias when we increase the degree of the neutralization of our plasmas. Partially neutralized plasmas are also characterized by multiple mode behavior with dominant modes between 20 and 200 kHz. When the plasma becomes quasineutral, it reverts to single mode behavior. The first results on partially neutralized plasmas confined on magnetic surfaces will be presented. [1] J. Kremer, PRL 97, (2006) 095003 [2] Q. Marksteiner, PRL 100 (2008) 065002

  1. How Objective a Neutral Word Is? A Neutrosophic Approach for the Objectivity Degrees of Neutral Words

    Directory of Open Access Journals (Sweden)

    Mihaela Colhon

    2017-11-01

    Full Text Available In the latest studies concerning the sentiment polarity of words, the authors mostly consider the positive and negative constructions, without paying too much attention to the neutral words, which can have, in fact, significant sentiment degrees. More precisely, not all the neutral words have zero positivity or negativity scores, some of them having quite important nonzero scores for these polarities. At this moment, in the literature, a word is considered neutral if its positive and negative scores are equal, which implies two possibilities: (1 zero positive and negative scores; (2 nonzero, but equal positive and negative scores. It is obvious that these cases represent two different categories of neutral words that must be treated separately by a sentiment analysis task. In this paper, we present a comprehensive study about the neutral words applied to English as is developed with the aid of SentiWordNet 3.0: the publicly available lexical resource for opinion mining. We designed our study in order to provide an accurate classification of the so-called “neutral words” described in terms of sentiment scores and using measures from neutrosophy theory. The intended scope is to fill the gap concerning the neutrality aspect by giving precise measurements for the words’ objectivity.

  2. Neutralization escape mutants define a dominant immunogenic neutralization site on hepatitis A virus

    International Nuclear Information System (INIS)

    Stapleton, J.T.; Lemon, S.M.

    1987-01-01

    Hepatitis A virus is an hepatotrophic human picornavirus which demonstrates little antigenic variability. To topologically map immunogenic sites on hepatitis A virus which elicit neutralizing antibodies, eight neutralizing monoclonal antibodies were evaluated in competition immunoassays employing radiolabeled monoclonal antibodies and HM-175 virus. Whereas two antibodies (K3-4C8 and K3-2F2) bound to intimately overlapping epitopes, the epitope bound by a third antibody (B5-B3) was distinctly different as evidenced by a lack of competition between antibodies for binding to the virus. The other five antibodies variably blocked the binding of both K3-4C8-K3-2F2 and B5-B3, suggesting that these epitopes are closely spaced and perhaps part of a single neutralization immunogenic site. Several combinations of monoclonal antibodies blocked the binding of polyclonal human convalescent antibody by greater than 96%, indicating that the neutralization epitopes bound by these antibodies are immunodominant in humans. Spontaneously arising HM-175 mutants were selected for resistance to monoclonal antibody-mediated neutralization. Neutralization resistance was associated with reduced antibody binding. These results suggest that hepatitis A virus may differ from poliovirus in possessing a single, dominant neutralization immunogenic site and therefore may be a better candidate for synthetic peptide or antiidiotype vaccine development

  3. Is a neutral expression also a neutral stimulus? A study with functional magnetic resonance.

    Science.gov (United States)

    Carvajal, Fernando; Rubio, Sandra; Serrano, Juan M; Ríos-Lago, Marcos; Alvarez-Linera, Juan; Pacheco, Lara; Martín, Pilar

    2013-08-01

    Although neutral faces do not initially convey an explicit emotional message, it has been found that individuals tend to assign them an affective content. Moreover, previous research has shown that affective judgments are mediated by the task they have to perform. Using functional magnetic resonance imaging in 21 healthy participants, we focus this study on the cerebral activity patterns triggered by neutral and emotional faces in two different tasks (social or gender judgments). Results obtained, using conjunction analyses, indicated that viewing both emotional and neutral faces evokes activity in several similar brain areas indicating a common neural substrate. Moreover, neutral faces specifically elicit activation of cerebellum, frontal and temporal areas, while emotional faces involve the cuneus, anterior cingulated gyrus, medial orbitofrontal cortex, posterior superior temporal gyrus, precentral/postcentral gyrus and insula. The task selected was also found to influence brain activity, in that the social task recruited frontal areas while the gender task involved the posterior cingulated, inferior parietal lobule and middle temporal gyrus to a greater extent. Specifically, in the social task viewing neutral faces was associated with longer reaction times and increased activity of left dorsolateral frontal cortex compared with viewing facial expressions of emotions. In contrast, in the same task emotional expressions distinctively activated the left amygdale. The results are discussed taking into consideration the fact that, like other facial expressions, neutral expressions are usually assigned some emotional significance. However, neutral faces evoke a greater activation of circuits probably involved in more elaborate cognitive processing.

  4. Neutron production by neutral beam sources

    International Nuclear Information System (INIS)

    Berkner, K.H.; Massoletti, D.J.; McCaslin, J.B.; Pyle, R.V.; Ruby, L.

    1979-11-01

    Neutron yields, from interactions of multiampere 40- to 120-keV deuterium beams with deuterium atoms implanted in copper targets, have been measured in order to provide input data for shielding of neutral-deuterium beam facilities for magnetic fusion experiments

  5. Neutron production by neutral beam sources

    Energy Technology Data Exchange (ETDEWEB)

    Berkner, K.H.; Massoletti, D.J.; McCaslin, J.B.; Pyle, R.V.; Ruby, L.

    1979-11-01

    Neutron yields, from interactions of multiampere 40- to 120-keV deuterium beams with deuterium atoms implanted in copper targets, have been measured in order to provide input data for shielding of neutral-deuterium beam facilities for magnetic fusion experiments.

  6. The buffer effect in neutral electrolyte supercapacitors

    DEFF Research Database (Denmark)

    Thrane Vindt, Steffen; Skou, Eivind M.

    2016-01-01

    The observation that double-layer capacitors based on neutral aqueous electrolytes can have significantly wider usable potential windows than those based on acidic or alkaline electrolytes is studied. This effect is explained by a local pH change taking place at the electrode surfaces, leading...... potassium nitrate as the electrolyte and potassium phosphates as the buffer system....

  7. Special solutions of neutral functional differential equations

    Directory of Open Access Journals (Sweden)

    Győri István

    2001-01-01

    Full Text Available For a system of nonlinear neutral functional differential equations we prove the existence of an -parameter family of "special solutions" which characterize the asymptotic behavior of all solutions at infinity. For retarded functional differential equations the special solutions used in this paper were introduced by Ryabov.

  8. Engineering problems of future neutral beam injectors

    International Nuclear Information System (INIS)

    Fink, J.

    1977-01-01

    Because there is no limit to the energy or power that can be delivered by a neutral-beam injector, its use will be restricted by either its cost, size, or reliability. Studies show that these factors can be improved by the injector design, and several examples, taken from mirror reactor studies, are given

  9. Development of KSTAR Neutral Beam Heating System

    Energy Technology Data Exchange (ETDEWEB)

    Oh, B. H.; Song, W. S.; Yoon, B. J. (and others)

    2007-10-15

    The prototype components of a neutral beam injection (NBI) system have been developed for the KSTAR, and a capability of the manufactured components has been tested. High power ion source, acceleration power supply, other ion source power supplies, neutralizer, bending magnet for ion beam separation, calorimeter, and cryo-sorption pump have been developed by using the domestic technologies and tested for a neutral beam injection of 8 MW per beamline with a pulse duration of 300 seconds. The developed components have been continuously upgraded to achieve the design requirements. The development technology of high power and long pulse neutral beam injection system has been proved with the achievement of 5.2 MW output for a short pulse length and 1.6 MW output for a pulse length of 300 seconds. Using these development technologies, the domestic NB technology has been stabilized under the development of high power ion source, NB beamline components, high voltage and current power supplies, NB diagnostics, NB system operation and control.

  10. ICAN: High power neutral beam generation

    International Nuclear Information System (INIS)

    Moustaizis, S.D.; Lalousis, P.; Perrakis, K.; Auvray, P.; Larour, J.; Ducret, J.E.; Balcou, P.

    2015-01-01

    During the last few years there is an increasing interest on the development of alternative high power new negative ion source for Tokamak applications. The proposed new neutral beam device presents a number of advantages with respect to: the density current, the acceleration voltage, the relative compact dimension of the negative ion source, and the coupling of a high power laser beam for photo-neutralization of the negative ion beam. Here we numerically investigate, using a multi- fluid 1-D code, the acceleration and the extraction of high power ion beam from a Magnetically Insulated Diode (MID). The diode configuration will be coupled to a high power device capable of extracting a current up to a few kA with an accelerating voltage up to MeV. An efficiency of up to 92% of the coupling of the laser beam, is required in order to obtain a high power, up to GW, neutral beam. The new high energy, high average power, high efficiency (up to 30%) ICAN fiber laser is proposed for both the plasma generation and the photo-neutralizer configuration. (authors)

  11. elative controllability of nonlinear neutral Volterra Integrodiferential ...

    African Journals Online (AJOL)

    In this paper we established sufficient conditions for the relative controllability of the nonlinear neutral volterra integro-differential systems with distributed delays in the control. The results were established using the Schauder's fixed point theorem which is an extension of known results. Journal of the Nigerian Association of ...

  12. If It's Neutral, It's Not Technology

    Science.gov (United States)

    Strate, Lance

    2012-01-01

    Taking a media ecology perspective, this article argues that technology cannot be neutral, because it is a form of change, and it has an inherent bias based on the properties of its materials and methods. Additionally, the application of a technology is an intrinsic part of the technology itself, as is technique, instructions, software, or…

  13. Neutral beam data systems at ORNL

    International Nuclear Information System (INIS)

    Stewart, C.R.

    1982-01-01

    A control system for neutral injection beam lines has been designed, implemented, and used with much success. Despite the problems with very high power levels this system is very successful in relieving the operators burdens of slow conditioning, data recording, and mode switching. The use of computer control with multiple beam lines now appears very promising

  14. Risk neutral second best toll pricing.

    Science.gov (United States)

    2011-08-01

    We propose a risk-neutral second best toll pricing scheme to account for the possible no uniqueness : of user equilibrium solutions. The scheme is designed to optimize for the expected objective value : as the UE solution varies within the solution s...

  15. Neutral theory of chemical reaction networks

    International Nuclear Information System (INIS)

    Lee, Sang Hoon; Holme, Petter; Minnhagen, Petter; Bernhardsson, Sebastian; Kim, Beom Jun

    2012-01-01

    To what extent do the characteristic features of a chemical reaction network reflect its purpose and function? In general, one argues that correlations between specific features and specific functions are key to understanding a complex structure. However, specific features may sometimes be neutral and uncorrelated with any system-specific purpose, function or causal chain. Such neutral features are caused by chance and randomness. Here we compare two classes of chemical networks: one that has been subjected to biological evolution (the chemical reaction network of metabolism in living cells) and one that has not (the atmospheric planetary chemical reaction networks). Their degree distributions are shown to share the very same neutral system-independent features. The shape of the broad distributions is to a large extent controlled by a single parameter, the network size. From this perspective, there is little difference between atmospheric and metabolic networks; they are just different sizes of the same random assembling network. In other words, the shape of the degree distribution is a neutral characteristic feature and has no functional or evolutionary implications in itself; it is not a matter of life and death. (paper)

  16. Neutral gas transport modeling with DEGAS 2

    International Nuclear Information System (INIS)

    Karney, C.; Stotler, D.

    1993-01-01

    The authors are currently re-writing the neutral gas transport code, DEGAS, with a view to making it both faster and easier to include new physics. They present model calculations including ionization and charge exchange illustrating the way that reactions are included into DEGAS 2 and its operation on a distributed network of workstations

  17. Niche versus neutrality: a dynamical analysis

    Science.gov (United States)

    Michael Kalyuzhny; Efrat Seri; Rachel Chocron; Curtis H. Flather; Ronen Kadmon; Nadav M. Shnerb

    2014-01-01

    Understanding the forces shaping ecological communities is of crucial importance for basic science and conservation. After 50 years in which ecological theory has focused on either stable communities driven by niche-based forces or nonstable “neutral” communities driven by demographic stochasticity, contemporary theories suggest that ecological communities are driven...

  18. Laser cooling and trapping of neutral atoms

    International Nuclear Information System (INIS)

    Phillips, W.D.

    1998-01-01

    The article is a translation of the lecture given on the occasion of the 1997 Nobel Prize awarding ceremony. The history of the discovery of laser cooling and trapping of neutral atoms is described. An explanation of this phenomenon is presented and the author's personal contribution to the discovery is highlighted. The article is completed by Dr. Phillips' autobiography. (Z.J.)

  19. Possible neutral beam requirements for TFTR upgrades

    International Nuclear Information System (INIS)

    Prichard, B.A. Jr.; Little, R.; Post, D.E.; Schmidt, J.A.

    1977-01-01

    A discussion is provided of possible neutral beam requirements and constraints for a TFTR upgrade. The time scale is the early 80s and beams of 250 keV D 0 , probably using 65 ampere negative ion sources, existing power supplies and vacuum enclosures would be required

  20. Transition radiation of ultrarelativistic neutral particles

    International Nuclear Information System (INIS)

    Grimus, W.; Neufeld, H.

    1994-10-01

    We perform a quantum theoretical calculation of transition radiation by neutral particles with spin 1/2 equipped with magnetic moments and/or electric dipole moments. The limit of vanishing masses is treated exactly for arbitrary refraction index. Finally we apply our result to the solar neutrino flux. (author)

  1. A storage ring for neutral molecules

    NARCIS (Netherlands)

    Crompvoets, F.M.H.

    2005-01-01

    Time-varying inhomogeneous electric fields can be used to manipulate the motion of neutral molecules in phase-space, i.e., position-momentum space, via their electric dipole moment. A theoretical background is given on the motion of the molecules in phase-space. As the forces exerted on the

  2. Modeling of the lithium based neutralizer for ITER neutral beam injector

    Energy Technology Data Exchange (ETDEWEB)

    Dure, F., E-mail: franck.dure@u-psud.fr [LPGP, Laboratoire de Physique des Gaz et Plasmas, CNRS-Universite Paris Sud, Orsay (France); Lifschitz, A.; Bretagne, J.; Maynard, G. [LPGP, Laboratoire de Physique des Gaz et Plasmas, CNRS-Universite Paris Sud, Orsay (France); Simonin, A. [IRFM, Institut de Recherche sur la Fusion Magnetique, CEA Cadarache, 13108 Saint-Paul lez Durance (France); Minea, T. [LPGP, Laboratoire de Physique des Gaz et Plasmas, CNRS-Universite Paris Sud, Orsay (France)

    2012-04-04

    Highlights: Black-Right-Pointing-Pointer We compare different lithium based neutraliser configurations to the deuterium one. Black-Right-Pointing-Pointer We study characteristics of the secondary plasma and the propagation of the 1 MeV beam. Black-Right-Pointing-Pointer Using lithium increases the neutralisation effiency keeping correct beam focusing. Black-Right-Pointing-Pointer Using lithium also reduces the backstreaming effect in direction of the ion source. - Abstract: To achieve thermonuclear temperatures necessary to produce fusion reactions in the ITER Tokamak, additional heating systems are required. One of the main method to heat the plasma ions in ITER will be the injection of energetic neutrals (NBI). In the neutral beam injector, negative ions (D{sup -}) are electrostatically accelerated to 1 MeV, and then stripped of their extra electron via collisions with a target gas, in a structure known as neutralizer. In the current ITER specification, the target gas is deuterium. It has been recently proposed to use lithium vapor instead of deuterium as target gas in the neutralizer. This would allow to reduce the gas load in the NBI vessel and to improve the neutralization efficiency. A Particle-in-Cell Monte Carlo code has been developed to study the transport of the beams and the plasma formation in the neutralizer. A comparison between Li and D{sub 2} based neutralizers made with this code is presented here, as well as a parametric study on the geometry of the Li based neutralizer. Results demonstrate the feasibility of a Li based neutralizer, and its advantages with respect to the deuterium based one.

  3. Comparison contemporary methods of regeneration sodium-cationic filters

    Science.gov (United States)

    Burakov, I. A.; Burakov, A. Y.; Nikitina, I. S.; Verkhovsky, A. E.; Ilyushin, A. S.; Aladushkin, S. V.

    2017-11-01

    Regeneration plays a crucial role in the field of efficient application sodium-cationic filters for softening the water. Traditionally used as regenerant saline NaCl. However, due to the modern development of the energy industry and its close relationship with other industrial and academic sectors the opportunity to use in the regeneration of other solutions. The report estimated data and application possibilities as regenerant solution sodium-cationic filters brine wells a high mineral content, as both primary application and after balneotherapeutic use reverse osmosis and concentrates especially recycled regenerant water repeated. Comparison of the effectiveness of these solutions with the traditional use of NaCl. Developed and tested system for the processing of highly mineralized brines wells after balneological use. Recommendations for use as regeneration solutions for the sodium-cationic unit considered solutions and defined rules of brine for regeneration costs.

  4. Gamma-irradiated cationic starches: Paper surface-sizing agents

    International Nuclear Information System (INIS)

    Hofreiter, B.T.; Heath, H.D.; Schulte, M.I.; Phillips, B.S.

    1981-01-01

    Cationic starches, precisely depolymerized by gamma-irradiation ( 60 Co), were dispersed in mild alkali and evaluated as surface sizes for bond paper on a pilot paper machine. The irradiated products had excellent dispersion properties, were well retained on fibers when sized wastepaper (broke) was repulped and had an ability to enhance paper properties that was comparable to that of starch-based materials used commercially. A yellow corn flour, cationized by an essentially dry reaction process recently developed at this Center, was also radiolyzed and evaluated as a size. This latter product was unique in that all drying steps were eliminated in the preparation of a cationic ceral product of reduced viscosity. (orig.) [de

  5. Nanoscale encapsulation: the structure of cations in hydrophobic microporous aluminosilicates

    International Nuclear Information System (INIS)

    Wasserman, S.R.; Yuchs, S.E.; Giaquinta, D.; Soderholm, L.; Song, Kang.

    1996-01-01

    Hydrophobic microporous aluminosilicates, created by organic surface modification of inherently hydrophilic materials such as zeolites and clays, are currently being investigated as storage media for hazardous cations. Use of organic monolayers to modify the surface of an aluminosilicate after introducing an ion into the zeolite/clay reduces the interaction of water with the material. Resulting systems are about 20 times more resistant to leaching of stored ion. XAS spectra from the encapsulated ion demonstrate that byproducts from the organic modifier can complex with the stored cation. This complexation can result in a decreased affinity of the cation for the aluminosilicate matrix. Changing the organic modifier eliminates this problem. XAS spectra also indicate that the reactivity and speciation of the encapsulated ion may change upon application of the hydrophobic layer

  6. Radical Addition to Iminium Ions and Cationic Heterocycles

    Directory of Open Access Journals (Sweden)

    Johannes Tauber

    2014-10-01

    Full Text Available Carbon-centered radicals represent highly useful reactive intermediates in organic synthesis. Their nucleophilic character is reflected by fast additions to electron deficient C=X double bonds as present in iminium ions or cationic heterocycles. This review covers diverse reactions of preformed or in situ-generated cationic substrates with various types of C-radicals, including alkyl, alkoxyalkyl, trifluoromethyl, aryl, acyl, carbamoyl, and alkoxycarbonyl species. Despite its high reactivity, the strong interaction of the radical’s SOMO with the LUMO of the cation frequently results in a high regioselectivity. Intra- and intermolecular processes such as the Minisci reaction, the Porta reaction, and the Knabe rearrangement will be discussed along with transition metal and photoredox catalysis or electrochemical methods to generate the odd-electron species.

  7. A covalent attraction between two molecular cation TTF·~+

    Institute of Scientific and Technical Information of China (English)

    WANG FangFang; WANG Yi; WANG BingQiang; WANG YinFeng; MA Fang; Li ZhiRu

    2009-01-01

    The optimized structure of the tetrathiafulvalence radical-cation dimer (TTF·~+-TTF·~+) with all-real frequencies is obtained at MP2/6-311G level,which exhibits the attraction between two molecular cation TTF·~+.The new attraction interaction is a 20-center-2-electron intermolecular covalent π/π bonding with a telescope shape.The covalent π/π bonding has the bonding energy of about-21 kcal·mol~(-1) and is concealed by the Coulombic repulsion between two TTF·~+ cations.This intermolecular covalent attraction also influences the structure of the TTF·~+ subunit,I.e.,its molecular plane is bent by an angle θ=5.6°.This work provides new knowledge on intermolecular interaction.

  8. A covalent attraction between two molecular cation TTF·~+

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The optimized structure of the tetrathiafulvalence radical-cation dimer(TTF·+-TTF·+) with all-real frequencies is obtained at MP2/6-311G level,which exhibits the attraction between two molecular cation TTF·+.The new attraction interaction is a 20-center-2-electron intermolecular covalent π /π bonding with a telescope shape.The covalent π /π bonding has the bonding energy of about -21 kcal·mol-1 and is concealed by the Coulombic repulsion between two TTF·+ cations.This intermolecular covalent attraction also influences the structure of the TTF·+ subunit,i.e.,its molecular plane is bent by an angle θ=5.6°.This work provides new knowledge on intermolecular interaction.

  9. Intracrystalline cation order in a lunar crustal troctolite

    Science.gov (United States)

    Smyth, J. R.

    1975-01-01

    Lunar sample 76535 appears to be one of the most slowly cooled bits of silicate material yet studied. It provides, therefore, a unique opportunity for the study of ordering processes in the minerals present. A better understanding of these processes may permit better characterization of the thermal history of this and similar rocks. The cation ordering in the olivine is consistent with terrestrial olivines favoring the interpretation that ordering in olivines increases with increasing temperature. In low bronzite, the deviations from the common orthopyroxene space group appear to be caused by cation order on the basis of four M sites instead of two. The degree of cation order in each of these minerals is consistent with the rock having been excavated from its depth of formation by tectonic or impact processes without being reheated above 300 C.

  10. Cationic mobility in polystyrene sulfone exchangers - Application to the elution of a cation on an exchange column

    International Nuclear Information System (INIS)

    Menin, Jean-Pierre

    1969-01-01

    The aim of this work is to improve elutions and separations carried out on inorganic exchangers by selective electromigration of the ionic species to be displaced. To do this, it has been found indispensable to make a fundamental study of the mobility of cations in exchangers. As the field for this research we have chosen those organic exchangers whose structure and behaviour with respect to ion-exchange are much better known that in the case of their inorganic equivalents. We have related the idea of the equivalent conductivity to that of the cation mobility in the exchanger, and this has entailed determining the specific conductivity of the exchanger and the cation concentration in the resin. The results obtained have allowed us to draw up a hypothesis concerning the cation migration mechanism in the exchanger. The third part of our work has been the application of the preceding results to an operation on an ion-exchange column, viz. the elution by an acid solution of a single fixed ion, magnesium or strontium. This work has enabled us to show that the electromigration of a cation during its elution can markedly accelerate or retard this elution. (author) [fr

  11. Effect of cation exchange of major cation chemistry in the large scale redox experiment at Aespoe. Revision 1

    International Nuclear Information System (INIS)

    Viani, B.E.; Bruton, C.J.

    1996-06-01

    Geochemical modeling was used to test the hypothesis that cation exchange with fracture-lining clays during fluid mixing in the Aespoe Hard Rock Laboratory can significantly affect major element chemistry. Conservative mixing models do not adequately account for changes in Na, Ca and Mg concentrations during mixing. Mixing between relatively dilute shallow waters and more concentrated waters at depth along fracture zones was modeled using the EQ3/6 geochemical modeling package. A cation exchange model was added to the code to describe simultaneously aqueous speciation, mineral precipitation/dissolution, and equilibration between a fluid and a cation exchanger. Fluid chemistries predicted to result from mixing were compared with those monitored from boreholes intersecting the fracture zone. Modeling results suggest that less than 0.1 equivalent of a smectite exchanger per liter of groundwater is necessary to account for discrepancies between predictions from a conservative mixing model and measured Na and Ca concentrations. This quantity of exchanger equates to an effective fracture coating thickness of 20 microm or less given a fracture aperture width of 1,000 microm or less. Trends in cation ratios in the fluid cannot be used to predict trends in cation ratios on the exchanger because of the influence of ionic strength on heterovalent exchange equilibrium. It is expected that Na for Ca exchange will dominate when shallow waters such as HBHO2 are mixed with deeper waters. In contrast, Na for Mg exchange will dominate mixing between deeper waters

  12. Misconceptions and false expectations in neutral evolution

    Directory of Open Access Journals (Sweden)

    CARLOS Y. VALENZUELA

    2000-01-01

    Full Text Available Neutral evolution results from random recurrent mutation and genetic drift. A small part of random evolution, that which is related to protein or DNA polymorphisms, is the subject of the Neutral Theory of Evolution. One of the foundations of this theory is the demonstration that the mutation rate (m is equal to the substitution rate. Since both rates are independent of population size, they are independent of drift, which is dependent upon population size. Neutralists have erroneously equated the substitution rate with the fixation rate, despite the fact that they are antithetical conceptions. The neutralists then applied the random walk stochastic model to justify alleles or bases that were fixated or eliminated. In this model, once the allele or base frequencies reach the monomorphic states (values of 1.0 or 0.0, the absorbing barriers, they can no longer return to the polymorphic state. This operates in a pure mathematical model. If recurrent mutation occurs (as in biotic real systems fixation and elimination are impossible. A population of bacteria in which m=10-8 base mutation (or substitution/site/generation and the reproduction rate is 1000 cell cycle/year should replace all its genome bases in approximately 100,000 years. The expected situation for all sites is polymorphism for the four bases rather than monomorphism at 1.0 or 0.0 frequencies. If fixation and elimination of a base for more than 500,000 years are impossible, then most of the neutral theory is untenable. A new complete neutral model, which allows for recurrent substitutions, is proposed here based on recurrent mutation or substitution and drift alone. The model fits a binomial or Poisson distribution and not a geometric one, as does neutral theory.

  13. Corrosion inhibition by inorganic cationic inhibitors on the high strength alumunium alloy, 2024-T3

    Science.gov (United States)

    Chilukuri, Anusha

    The toxicity and carcinogenic nature of chromates has led to the investigation of environmentally friendly compounds that offer good corrosion resistance to AA 2024-T3. Among the candidate inhibitors are rare earth metal cationic (REM) and zinc compounds, which have received much of attention over the past two decades. A comparative study on the corrosion inhibition caused by rare earth metal cations, Ce3+, Pr3+, La3+ and Zn2+ cations on the alloy was done. Cathodic polarization showed that these inhibitor ions suppress the oxygen reduction reaction (ORR) to varying extents with Zn2+ providing the best inhibition. Pr3+ exhibited windows of concentration (100-300 ppm) in which the corrosion rate is minimum; similar to the Ce3+ cation. Scanning Electron Microscopy (SEM) studies showed that the mechanism of inhibition of the Pr3+ ion is also similar to that of the Ce3+ ion. Potentiodynamic polarization experiments after 30 min immersion time showed greatest suppression of oxygen reduction reaction in neutral chloride solutions (pH 7), which reached a maximum at a Zn2+ ion concentration of 5 mM. Anodic polarization experiments after 30 min immersion time, showed no anodic inhibition by the inhibitor in any concentration (0.1 mM - 10 mM) and at any pH. However, anodic polarization of samples immersed after longer immersion times (upto 4 days) in mildly acidic Zn2+ (pH 4) solutions showed significant reduction in anodic kinetics indicating that zinc also acts as a “slow anodic inhibitor”. In contrast to the polarization experiments, coupons exposed to inhibited acidic solutions at pH 4 showed complete suppression of dissolution of Al2CuMg particles compared to zinc-free solutions in the SEM studies. Samples exposed in pH 4 Zn2+-bearing solution exhibited highest polarization resistance which was also observed to increase with time. In deaerated solutions, the inhibition by Zn2+ at pH 4 is not observed as strongly. The ability to make the interfacial electrolyte

  14. Photoinducedly electrochemical preparation of Prussian blue film and electrochemical modification of the film with cetyltrimethylammonium cation

    Energy Technology Data Exchange (ETDEWEB)

    Liu Shouqing, E-mail: shouqing_liu@hotmail.co [Key Laboratory of Environmental Functional Materials of Jiangsu Province, College of Chemistry and Bioengineering, Suzhou University of Science and Technology, Suzhou 215009 (China); Li Hua; Sun Weihui; Wang Xiaomei; Chen Zhigang [Key Laboratory of Environmental Functional Materials of Jiangsu Province, College of Chemistry and Bioengineering, Suzhou University of Science and Technology, Suzhou 215009 (China); Xu Jingjuan; Ju Huangxian; Chen Hongyuan [Key Laboratory of Analytical Chemistry for Life Science, Ministry of Education, Nanjing University, Nanjing 210093 (China)

    2011-04-15

    Research highlights: {yields} Cetyltrimethylammonium cations work as counter ions in Prussian blue film was observed and confirmed by cyclic voltammetry, Fourier transform infrared spectroscopy, X-ray powder diffraction measurements, scanning electronic microscopy and transmission electron microscope for the first time. {yields} Because the cetyltrimethylammonium cations in Prussian blue film are hydrophobic, the Prussian blue film is very stable even in alkali solution, which provides a technical basis for fabrication of stable biosensors. - Abstract: This work presents a photoinducedly electrochemical preparation of Prussian blue from a single sodium nitroprusside and insertion of cetyltrimethylammonium cations into Prussian blue as counter ions. The product of photoinducedly electrochemical reactions has a couple of voltammetric peaks at E{sup o} = 0.266 V in 0.2 mol l{sup -1} KCl solution, the measurements of X-ray powder diffraction and FT-IR spectroscopy show that it is Prussian blue (PB). The formation mechanism of a pre-photochemical reaction and subsequent electrochemical reaction is suggested. The cyclic voltammetric treatment of the freshly as-prepared PB film in 1.0 mmol l{sup -1} cetyltrimethylammonium (CTA) bromide solution leads to the insertion of cetyltrimethylammonium cations into the channels of Prussian blue, which substitutes for potassium ions as counter ions in Prussian blue. The Prussian blue containing CTA counter ions shows two couples of voltammetric peaks at E{sup o} = -0.106 V and E{sup o} = 0.249 V in 0.2 mol l{sup -1} KCl solution containing 1.0 mmol l{sup -1} cetyltrimethylammonium bromide. Compared with the electrochemical behaviors of KFeFe(CN){sub 6} in 0.1 mol l{sup -1} KOH alkali solution, CTAFeFe(CN){sub 6} shows relatively durable voltammetric currents due to the hydrophobic effects of cetyltrimethylammonium. The diffusion coefficients for CTA and potassium cations were estimated to be D{sub CTA} 1.25 x 10{sup -12} cm{sup 2} s

  15. Thermodynamics and Cation Diffusion in the Oxygen Ion Conductor Lsgm

    Science.gov (United States)

    Martin, M.; Schulz, O.

    Perovskite type oxides based on LaGaO3 are of large technical interest because of their high oxygen-ion conductivity. Lanthanum gallate doped with Sr on A- and Mg on B-sites, La1-xSrxGa1-yMgyO3-(x+y)/2 (LSGM), reaches higher oxygen-ion conductivities than yttria-doped zirconia (YSZ). Thus LSGM represents a promising alternative for YSZ as electrolyte in solid oxide fuel cells (SOFC). Cells using thin LSGM-layers as electrolyte are expected to operate at intermediate temperatures around 700°C for more than 30000 hours without severe degradation. A potential long term degradation effect of LSGM is kinetic demixing of the electrolyte, caused by different cation diffusion coefficients. In this paper we report on experimental studies concerning the phase diagram of LSGM and the diffusion of cations. Cation self-diffusion of 139La, 84Sr and 25Mg and cation impurity diffusion of 144Nd, 89Y and 56Fe in polycrystalline LSGM samples was investigated by secondary ion mass spectrometry (SIMS) for temperatures between 900°C and 1400°C. It was found that diffusion occurs by means of bulk and grain boundaries. The bulk diffusion coefficients are similar for all cations with activation energies which are strongly dependent on temperature. At high temperatures, the activation energies are about 5 eV, while at low temperatures values of about 2 eV are found. These results are explained by a frozen in defect structure at low temperatures. This means that the observed activation energy at low temperatures represents only the migration energy of the different cations while the observed activation energy at high temperatures is the sum of the defect formation energy and the migration energy. The migration energies for all cations are nearly identical, although 139La, 84Sr and 144Nd are occupying A-sites while 25Mg and 56Fe are occupying B-sites in the perovskite-structure. To explain these experimental findings we propose a defect cluster containing cation vacancies in both the A

  16. Inward Cationic Diffusion and Percolation Transition in Glass-Ceramics

    DEFF Research Database (Denmark)

    Smedsklaer, Morten Mattrup; Yue, Yuanzheng; Mørup, Steen

    2010-01-01

    We show the quantitative correlation between the degree of crystallization and the cationic diffusion extent in iron-containing diopside glass–ceramics at the glass transition temperature. We find a critical degree of crystallization, above which the diffusion extent sharply drops with the degree...... of crystallization. Below the critical value, the diffusion extent decreases only slightly with the degree of crystallization. No cationic diffusion is observed in the fully crystalline materials. The critical value might be associated with a percolation transition from an interconnected to a disconnected glass...

  17. Radiation-induced cationic curing of vinyl ethers

    International Nuclear Information System (INIS)

    Lapin, S.C.

    1992-01-01

    Recently there has been an increasing interest in nonacrylate radiation-curable coatings. Vinyl ethers are particularly reactive under cationic polymerization reaction conditions. The high efficiency of the photoacid initiators combined with the high reactivity of vinyl ether monomers makes this a potentially very useful system. This chapter discusses the preparation of vinyl ethers, introduces vinyl ether-functional monomers and oligomers, describes radiation-induced cationic polymerization of vinyl ethers, and discusses various coating systems. Throughout the chapter, an emphasis is placed on radiation-curable coating applications. 64 refs., 5 figs., 11 tabs

  18. Conductometric determination of solvation numbers of alkali metal cations

    International Nuclear Information System (INIS)

    Fialkov, Yu.Ya.; Gorbachev, V.Yu.; Chumak, V.L.

    1997-01-01

    Theories describing the interrelation of ion mobility with their effective radii in solutions are considered. Possibility of using these theories for determination the solvation numbers n s of some ions is estimated. According to conductometric data values of n s are calculated for alkali metal ions in propylene carbonate. The data obtained are compared with solvation numbers determined with the use of entropies of ions solvation. Change of n s values within temperature range 273.15-323.15 K is considered. Using literature data the effect of crystallographic radii of cations and medium permittivity on the the values of solvation numbers of cations are analyzed. (author)

  19. Membrane potential and cation channels in rat juxtaglomerular cells

    DEFF Research Database (Denmark)

    Friis, U G; Jørgensen, F; Andreasen, D

    2004-01-01

    The relationship between membrane potential and cation channels in juxtaglomerular (JG) cells is not well understood. Here we review electrophysiological and molecular studies of JG cells demonstrating the presence of large voltage-sensitive, calcium-activated potassium channels (BK(Ca)) of the Z......The relationship between membrane potential and cation channels in juxtaglomerular (JG) cells is not well understood. Here we review electrophysiological and molecular studies of JG cells demonstrating the presence of large voltage-sensitive, calcium-activated potassium channels (BK...

  20. Is the stoichiometry of the europium nitrate complexes with neutral organophosphorus extractants be anticipated?

    International Nuclear Information System (INIS)

    Beudaert, Ph.; Lamare, V.; Wipff, G.

    2001-01-01

    Molecular dynamics simulations have been performed in water on europium nitrate complexes with three neutral organophosphorus extractants (TBP, TPPO and CMPO) in order to determine on what criteria it is possible to obtain by simulations the experimental 1:3 stoichiometry in organic solution. This stoichiometry was investigated by progressive saturation of the cation coordination sphere. When the nitrate counter-ions are bidentate, the 1:3 stoichiometry corresponds to the degree of saturation where the interaction energy between europium and water becomes repulsive. Beyond this stoichiometry, complexes with TPPO and CMPO are unstable, although a 1:4 complex with TBP may exist but its formation appears to be energetically unfavored. (author)