zwitterionic protonated cationic: Topics by WorldWideScience.org

Proton-loaded zeolites. 2. Dehydrohalogenation versus decationization kinetics: Cation and acidity effects

The influence of membrane pH gradients on the transbilayer distribution of some common phospholipids has been investigated. The authors demonstrate that the transbilayer equilibrium of the acidic phospholipids egg phosphatidylglycerol (EPG) and egg phosphatidic acid (EPA) can be manipulated by membrane proton gradients, whereas phosphatidylethanolamine, a zwitterionic phospholipid, remains equally distributed between the inner and outer monolayers of large unilamellar vesicles (LUVs). Asymmetry of EPG is examined in detail and demonstrated by employing three independent techniques: ion-exchange chromatography, {sup 13}C NMR, and periodic acid oxidation of the (exterior) EPG headgroup. In the absence of a transmembrane pH gradient ({Delta}pH) EPG is equally distributed between the outer and inner monolayers of LuVs. When vesicles composed of either egg phosphatidylcholine (EPC) or DOPC together with 5 mol % EPG are prepared with a transmembrane ...

1989-05-16

2

Antibiotic interaction with phospholipid monolayers

The work presented in part 1 of this study established that the sorption of anhydrous HX into dehydrated Na{sub 56}Y progresses through a sequence of steps involving HX ionization and charge separation, oxygen framework protonation, formation of {alpha}-cage confined cation-anion contact ion pairs, and proton solvation by HX. A logical extension, which is the subjected of this study, concerns the effect of extraframework alkali metal cation type (M = Li{sup +}, Na{sup +}, K{sup +}, Rb{sup +}, Cs{sup +}) on the sorption process. The question of the acidity of proton-loaded zeolites compared to Broensted acid zeolites is addressed by using probe reactions with weak bases like ethane and cyclopropane. Additional insight into these systems is also obtained from a quantitative comparison of the kinetic and thermodynamic activation parameters for the dehydrohalogenation of ...

1990-10-18

3

Metal ion complexation by ionizable crown ethers

We studied the interactions of tetracycline (TC) antibiotic molecules with phospholipid monolayers with the two-fold aim of elucidating the mechanism of action and providing a first step for the realization of bio-mimetic sensors for such drugs by means of the Langmuir-Blodgett technique. We examined spreading monolayers of three phospholipids in the presence of tetracycline in the subphase by means of surface pressure-area and surface potential-area isotherms as a function of bulk pH. We selected phospholipids with hydrophobic chains of the same length but polar head groups differing either in dimensions and protonation equilibria, i.e. dipalmitoylphosphatidylcholine (DPPC), dipalmitoylphosphatidylethanolamine (DPPE) and dipalmitoylphosphatidic acid (DPPA). The interaction of tetracycline with the three phospholipids was found to be highly dependent on the electric charge of the antibiotic and on the ionization state of the lipid. Significant interactions are ...

2002-12-01

4

Two rotary motors in F-ATP synthase are elastically coupled by a flexible rotor and a stiff stator stalk

Research conducted since the last progress report includes the synthesis and characterization of twenty three novel proton-ionizable crown ether compounds. Metal ion complexation behavior of new and previously-synthesized proton-ionizable crown ether compounds has been probed by solvent extraction and transport across polymer-supported liquid membranes. The behavior of neutral polyether and proton-ionizable polyether ligands in polymeric membrane electrodes has been assessed. Studies of the use of proton-ionizable crown ethers for separation of lithium isotopes were initiated. Also, the thermodynamics of interactions between alkali metal cations and ionized crown ethers have been probed by titration calorimetry. 10 refs., 1 tab.

1989-09-01

5

Electrophilic addition of astatine

ATP is synthesized by ATP synthase (F_OF₁-ATPase). Its rotary electromotor (F_O) translocates protons (in some organisms sodium cations) and generates torque to drive...Full Text Available

2011-03-08

6

Intermediate products of radiolytic conversions of 6-aminophenalenone in ethanol

It has been shown for the first time that astatine is capable of undergoing addition reactions to unsaturated hydrocarbons. A new compound of astatine, viz., ethylene astatohydrin, has been obtained, and its retention numbers of squalane, Apiezon, and tricresyl phosphate have been found. The influence of various factors on the formation of ethylene astatohydrin has been studied. It has been concluded on the basis of the results obtained that the univalent cations of astatine in an acidic medium is protonated hypoastatous acid.

7

Chemical properties of positive singly charged astatine ion in aqueous solution

Intermediate products of the conversions of 6-aminophenalenone in ethanol were investigated by pulse radiolysis. In alkaline medium the main product is the 6-aminophenalenone radical cation, the optical absorption spectrum of which contains two bands with maxima at 355 and 400 nm. The precursors of this particle are e_s, CH_3CHOH and CH_3CHO"- radicals. In neutral and acid medium, radical cations are protonated in reactions with alcohol and hydrogen ions. The H-adduct of 6-aminophenalenone that arises has optical absorption maxima at 350 and 390 nm. The presence of two maxima is due to two different structures of the product. The molar extinction coefficients of the radical anions and H-adducts of 6-aminophenalenone and the rate constants of the reactions involving them were estimated. 6 refs., 4 figs., 2 tabs.

1992-01-01

8

Chemical properties of positive singly charged astatine ion in aqueous solution

The mobility of oxidized astatine in solutions H(Na)ClO/sub 4/ (..mu..=0.4M)-1.10/sup -4/M K/sub 2/Cr/sub 2/O/sub 7/ has been measured at 25 degC in the interval 0.63<=pH<=1.68. Under these conditions astatine migrates to the cathode only. The speeds of the migration depends upon the concentration of hydrogen ions in solutions are: pH 1.68 Usub(c)=1.17.10/sup -4/ cm/sup 2/ V/sup -1/ s/sup -1/; pH 0.63 Usub(c)=2.67.10/sup -4/ cm/sup 2/ V/sup -1/ s/sup -1/. The effect agrees with the opinion that the singly charged cation of astatine formed in acidic solutions is a strong aquacomplex ((H/sub 2/O)sub(x)At)/sup +/ (x=1-2) (protonated hypoastatic acid). Deprotonation constant of this cation is Ksub(dp)=0.032+-0.005. Specific properties of the astatine cation are given. They can be explained, probably, through the peculiarities of its structure. 14 refs.

1984-08-01

9

Theory of zwitterionic molecular-based organic magnets

The mobility of oxidized astatine in solutions H(Na)ClO_4 (#mu#=0.4M)-1.10"-"4M K_2Cr_2O_7 has been measured at 25 degC in the interval 0.63<=pH<=1.68. Under these conditions astatine migrates to the cathode only. The speeds of the migration depends upon the concentration of hydrogen ions in solutions are: pH 1.68 Usub(c)=1.17.10"-"4 cm"2 V"-"1 s"-"1; pH 0.63 Usub(c)=2.67.10"-"4 cm"2 V"-"1 s"-"1. The effect agrees with the opinion that the singly charged cation of astatine formed in acidic solutions is a strong aquacomplex [(H_2O)sub(x)At]"+ (x=1-2) (protonated hypoastatic acid). Deprotonation constant of this cation is Ksub(dp)=0.032+-0.005. Specific properties of the astatine cation are given. They can be explained, probably, through the peculiarities of its structure. (author).

10

British Library Electronic Table of Contents (United Kingdom)

We describe a class of organic molecular magnets based on zwitterionic molecules (betaine derivatives) possessing donor, p bridge, and acceptor groups. Using extensive electronic structure calculations we show the electronic ground-state in these systems is magnetic. In addition, we show that the large energy differences computed for the various magnetic states indicate a high Neel temperature. The quantum mechanical nature of the magnetic properties originates from the conjugated p bridge (only p electrons) in cooperation with the molecular donor-acceptor character. The exchange interactions between electron spin are strong, local, and independent on the length of the p bridge.

2011-01-01

11

Low-energy ion-molecule reaction dynamics and chemiionization kinetics. Progress report, February 1, 1981-January 31, 1982

Characterisation of a re-cast composite Nafion 1100 series of proton exchange membranes incorporating inert inorganic oxide particles

This progress report concerns work completed or initiated since our last report in October of 1980. We have performed experiments in two major areas: photodissociation of organic cations to study the competition between isomerization and fragmentation; and, low energy proton transfer reactions of HCO"+ with selected neutrals. The former area provides a sideline to our combustion studies of proton transfer in hydrocarbon flames, but the question of energy transfer in highly excited gas phase ions impacts directly upon questions closely related to the fate of ions in combustion. The latter area, currently in progress, focuses upon the dynamics of biomolecular reactions of direct relevance to combustion.

12

Kinetics of carbon dioxide absorption in solutions of methyldiethanolamine

A series of cation exchange membranes was produced by impregnating and coating both sides of a quartz web with a Nafion solution (1100 EW, 10%wt in water). Inert filler particles (SiO_2, ZrO_2 or TiO_2; 5-20%wt) were incorporated into the aqueous Nafion solution to produce robust, composite membranes. Ion-exchange capacity/equivalent weight, water take-up, thickness change on hydration and ionic and electrical conductivity were measured in 1 mol dm"-"3 sulfuric acid at 298 K. The TiO_2 filler significantly impacted on these properties, producing higher water take-up and increased conductivity. Such membranes may be beneficial for proton exchange membrane (PEM) fuel cell operation at low humidification. The PEM fuel cell performance of the composite membranes containing SiO_2 fillers was examined in a Ballard Mark 5E unit cell. While the use of composite membranes offers a cost reduction, the unit cell performance was reduced, in practice, due ...

2010-09-01

13

A zwitterionic silylene as reactive intermediate and its unusual dimerization to an N-heterobicyclic disilane.

The kinetics of the reaction of carbon dioxide in MDEA solutions were studied both experimentally and theoretically. It is concluded that MDEA acts as a homogeneous catalyst for CO/sub 2/ hydrolysis, and as a result the rate of absorption in aqueous MDEA solutions is significantly larger than one would calculate by simply taking into account the alkalinity of the reaction. A possible zwitterion mechanism is proposed for this reaction. The minor effect of ionic strength were also studied with the presence of other ions. 19 references, 6 figures.

1985-01-01

14

Reasoning About Action II: The Quali cation Problem

A way to synthesize the transient zwitterionic silylene L'Si: 8 {L'=CH[(C=CH(2))CMe(N(tBu))(2)]} and achieve its facile dimerization to the remarkable N-heterobicyclic disilane 8(2) is described. At first, employing the beta-diketiminate ligand L [L=CH(CMeN(tBu))(2)], both starting materials LH (2) and its N-lithium salt LLi (3) can react with SiBr(4) to yield the silylene precursor L'SiBr(2) (4) by silicon-induced C-H activation at an exocyclic methyl group on the backbone of the ligand. Compound 4 reacts with SiBr(4) above room temperature to afford the unexpected terminal CH(SiBr(3))-substituted dibromosilane 6 along with the unique tricyclic trisilane 7. Reduction of 4 with KC(8) at 0 degrees C furnishes the novel N-heterobicyclic disilane 8(2), which is a formal dimer of the desired zwitterionic silylene L'Si: (8). It has been reasoned that compound 8(2) may results from [4+1] cycloaddition of two molecules of 8 to give the transient dimer ...

2009-08-01

15

Studies of {eta} production in proton proton collisions with the time of flight spectrometer

missionaries and cannibals puzzle. He noted that in order to be able to use a boat to cross a river one would need ... a quali cation that the vertical exhaust stack ...

16

RF System for Compact Medical Proton Synchrotron

No abstract prepared.

2002-03-01

17

RF Cavities and Power Amplifier for the Compact Proton Synchrotron

RF System for Compact Medical Proton Synchrotron

2004-01-01

18

Low Energy Part of the CONCERT High-Power Proton Linac

RF Cavities and Power Amplifier for the Compact Proton Synchrotron

2003-01-01

19

First Result of Induction Acceleration in the KEK Proton Synchrotron

Low Energy Part of the CONCERT High-Power Proton Linac

2001-01-01

20

Compact Proton and Carbon Ion Synchrotrons for Radiation Therapy

First Result of Induction Acceleration in the KEK Proton Synchrotron

2005-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

21

Beam Diagnostic System for High Intensity Proton Linac at KAERI

Compact Proton and Carbon Ion Synchrotrons for Radiation Therapy

2002-01-01

22

The radiobiological research of protons particles at the Orsay proton therapy center; La recherche radiobiologique des particules de protons au centre de protontherapie d'Orsay

Beam Diagnostic System for High Intensity Proton Linac at KAERI

2003-01-01

23

High resolution (p,p') reactions on "8"7Sr and "8"8Sr

No abstract prepared.

2003-11-01

24

Spectroscopic characterization of alkane radical cations: Pt. 1

... levels excited states mev range 10-100 proton reactions proton spectra protons

25

Evaluation of the addition of various surfactant-suspended carbon nanotubes in MEEKC with an in situ-synthesized surfactant system

Radical cations of various 3-methylalkanes (C_6-C_1_4) have been produced and stabilized by #gamma#-irradiation of the corresponding neutral compounds in saturated chlorofluorocarbon and perfluorocarbon matrices at 77 K. The perfluorocarbon matrices appeared more suitable for studies of the lighter radical cations, whereas the chlorofluorocarbon matrices were more suited for studies of the heavier radical cations; intermediary cations could be studied in both types of matrices. After irradiation, electronic absorptions associated with both the matrix and the alkane additive were observed. Pure spectra of the 3-methylalkane radical cations were obtained by difference spectrometry, after selective elimination of these cations by illumination. The electronic absorption spectra of the 3-methylalkane radical cations consist in all cases of a ...

1989-01-01

26

British Library Electronic Table of Contents (United Kingdom)

Abstract Dispersions of single-walled carbon nanotubes (SWNTs) in various surfactant solutions have been systematically evaluated as additives in MEEKC. The compounds examined were catechins, phenolic acids, and flavonoids. Compared with zwitterionic and neutral surfactants, the addition of anionic dispersion seemed to be better at separating the three types of analytes in microemulsion system. In order to achieve low operating currents, an in situ-synthesized surfactant system based on the combination of a long-chain alkyl acid with an organic base was used in MEEKC. The optimized buffer contained 0.5% (57-mM) ethyl acetate, 0.6% (30-mM) lauric acid, 4.0% (666-mM) propanol, 50-mM Tris solution, and 4.5-mg/L the dispersion of SWNTs. Under optimized conditions, the established method was ap...

2011-01-01

27

Spectrophotometric studies on the interactions of C.I. Basic Red 9 and C.I. Acid Blue 25 with hexadecyltrimethylammonium bromide in cationic surfactant micelles

British Library Electronic Table of Contents (United Kingdom)

Interactions between cationic dye-cationic surfactant and anionic dye-cationic surfactant systems were investigated in aqueous solutions using spectrophotometric method at 288.15, 298.15, 308.15 and 318.15K. C.I. Basic Red 9 (BR9) and C.I. Acid Blue 25 (AB25) were used as cationic and anionic dyes, respectively, and hexadecyltrimethylammonium bromide (HDTMABr) was selected as cationic surfactant in this study. Although there was an interaction between the AB25 and the HDTMABr molecules, an interaction between the BR9 and HDTMABr did not occur due to the electrostatic repulsion forces. Binding constants and partition coefficients between the micellar and the bulk water phases for the AB25-HDTMABr system were calculated from the changes in absorbance values and the critical micelle concentra...

2011-01-01

28

THE QUEST FOR COSMIC RAY PROTONS IN GALAXY CLUSTERS

KoreaScience (Korea)

Full Text Available

2004-12-01

29

Proton Transfer Reactivity of Large Multiply Charged Ions

Production of sup 203 Pb by proton irradiation of Bi

Charge-charge interactions dramatically influence the dissociation and proton transfer reactivity of large multiply protonated ions. In combination with tandem mass spectrometry, proton transfer...Full Text Available

1996-08-01

30

Maximum proton kinetic energy and patient-generated neutron fluence considerations in proton beam arc delivery radiation therapy

Short note.

1991-01-01

31

Isolation of carrier-free tantalum radioisotopes from proton-irradiated hafnium

Several compact proton accelerator systems for use in proton therapy have recently been proposed. Of paramount importance to the development of such an accelerator system is the maximum kinetic energy...Full Text Available

2009-02-01

32

#beta#-delayed proton decays of "8"1Zr and "8"5Mo

... carrier-free isotopes hafnium compounds irradiation protons solvent extraction

33

Use of Lipophilic Cations to Measure the Membrane Potential of Oat Leaf Protoplasts 1

... RADIATION PHYSICS beta decay delayed protons excited states experimental

34

Stimulation of albumin endocytosis by cationized ferritin in cultured aortic smooth muscle cells.

Uptake of the lipophilic cation triphenylmethylphosphonium into mesophyll protoplasts of oat (Avena sativa L. cv. “Garry”) approaches equilibrium at 3 to 4 hours. The...Full Text Available

1978-12-01

35

Difference in the effects produced by non-radioactive and radioactive calcium

Anionic microdomains within the aortic smooth muscle cell (SMC) surface glycocalyx represent a potential barrier to the endocytosis of anionic plasma proteins. Cultured SMCs exposed briefly to cationized...Full Text Available

1985-12-01

36

Structural changes of lower rank coals by cation exchange

... aluminum calcium calcium 45 cations citric acid corrosion inhibition radiation

37

Effect of vanadate on proton-sucrose cotransport in Ricinus cotyledons

Three subbituminous coals of different rank demineralized in HCl and HF aqueous solutions were treated with several metal salt aqueous solutions to produce corresponding cation exchanged coals. In this treatment, the demineralized coals were exchanged by cations (K{sup +}, Na{sup +}, Mg{sup 2+}, Ca{sup 2+}, Fe{sup 3+} and Al{sup 3+}), which are known to be the major elements in coal minerals. The relations between the content and the kind of exchanged cations were investigated. For lower rank coals, such as Adaro and Black Thunder coals, almost linear relations between the content of exchanged cations and the decreasing amounts of pyridine soluble yields of the cation exchanged coals based on the values in the respective demineralized coals were found. From the differences of the gradients, it was confirmed that the noncovalent associations such as hydrogen bonds between pyridine ...

1999-06-01

38

Identity and yield of positive charge centers in irradiated chloro hydrocarbon liquids and the rates of their interaction with solute molecules. [3-4 MeV electrons

The effects of orthovanadate on the uptake of sucrose by Ricinus cotyledons and on sucrose-coupled proton influx were measured in order to gain insight into the relationship to the plasma membrane proton pump. Vanadate had no effect on short-term sucrose uptake. In long-term experiments (> 30 min) sucrose uptake was progressively inhibited, but only at high external sucrose concentrations. Vanadate did not affect proton efflux pumping in the absence of sucrose and neither did it change the initial rate of sucrose-coupled proton influx. However, it enhanced the maximal level of sucrose-induced alkalization of the medium at all sucrose concentrations tested. This is interpreted as an inhibiting effect of vanadate on the proton pump that recycles protons during sucrose-proton cotransport. The sensitivity towards vanadate indicates that this ...

1987-07-01

39

Identity and yield of positive charge centers in irradiated chloro hydrocarbon liquids and the rates of their interaction with solute molecules

Pulse radiolysis studies of the formation kinetics and the yields of various phenylcarbenium ions from several different solutes in 1,2-dichloroethane solution have been carried out. The results indicate that there are two kinetically distinguishable cationic species of the solvent which react selectively with the different solutes to form the phenylcarbenium ions. It is suggested that one is a cation radical (yield 0.68 molecule/100 eV) and the other a carbocation (yield 0.20 molecule/100 eV). Rate constants for their separate reactions with selected aromatic compounds and with ammonia have been determined. Molar extinction coefficients have been estimated for benzyl cation, diphenyl cation radical, and anthracene cation radical. 6 figures, 1 table.

1979-07-26

40

Antiproton-Proton Channels in J/psi Decays

Pulse radiolysis studies of the formation kinetics and the yields of various phenylcarbenium ions from several different solutes in 1,2-dichloroethane solution have been carried out. The results indicate that there are two kinetically distinguishable cationic species of the solvent which react selectively with the different solutes to form the phenylcarbenium ions. It is suggested that one is a cation radical (yield 0.68 molecule/100 eV) and the other a carbocation (yield 0.20 molecule/100 eV). Rate constants for their separate reactions with selected aromatic compounds and with ammonia have been determined. Molar extinction coefficients have been estimated for benzyl cation, diphenyl cation radical, and anthracene cation radical. 6 figures, 1 table.

1979-07-01

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41

Improvement on CRUD removal efficiency by ion exchange resins

The recent measurements by the BES Collaboration of J/psi decays into a photon and a proton-antiproton pair indicate a strong enhancement at the proton-antiproton threshold not observed in the decays into a neutral pion and a proton-antiproton pair. Is this enhancement due to a proton-antiproton quasi-bound state or a baryonium? A natural explanation follows from a traditional model of proton-antiproton interactions based on G-parity transformation. The observed proton-antiproton structure is due to a strong attraction in the 1S0 state, and possibly to a near-threshold quasi-bound state in the 11S0 wave.

2005-01-01

42

Improvement on CRUD removal efficiency by ion exchange resins

Reduction of occupational radiation exposure dose in a BWR plant is achieved by an elimination of crud in a BWR primary loop condensate stream by condensate demineralizer. Crud removal by condensate polisher improves year by year, a phenomenon called the Aging Effect of Ion Exchange Resins. The cause of this phenomenon is assumed to be mainly due to changes in the cation resin property becoming more crud adsorptive, where a typical change in physical property of aged cation resin is an increase in water retention capacity. Assuming that the crud removal efficiency was influenced by a crosslinkage of cation resin, an attempt was made to enhance this removal efficiency by decreasing the crosslinkage and satisfactory results were obtained. As a result, new gel type cation resins were developed with lower crosslinkage and larger surface areas, as compared with conventional gel type resins. The crosslinkage ...

1989-10-01

43

Proton transport, an examination of model and experimental data for space environment protons; Blindage aux protons, comparaison entre modele et donnees experimentales pour les protons du rayonnement spatial

Reduction of occupational radiation exposure dose in a BWR plant is achieved by an elimination of crud in a BWR primary loop condensate stream by condensate demineralizer. Crud removal by condensate polisher improves year by year, a phenomenon called the Aging Effect of Ion Exchange Resins. The cause of this phenomenon is assumed to be mainly due to changes in the cation resin property becoming more crud adsorptive, where a typical change in physical property of aged cation resin is an increase in water retention capacity. Assuming that the crud removal efficiency was influenced by a crosslinkage of cation resin, an attempt was made to enhance this removal efficiency by decreasing the crosslinkage and satisfactory results were obtained. As a result, new gel type cation resins were developed with lower crosslinkage and larger surface areas, as compared with conventional gel type resins. The crosslinkage ...

44

ESR study of the aziridine and azetidine radical cations: evidence for the C...C ring-opened aziridine radical cation

We will examine modeling data for various orbits using modeling software and compare this with actual satellite flight result. In particular, we will discuss the contributions of trapped protons to total dose and the effectiveness of shielding.

1999-07-01

45

ESR study of the aziridine and azetidine radical cations: evidence for the C. C ring-opened aziridine radical cation

The radical cations from aziridine and azetidine have been characterized by ESR spectroscopy following their generation in the solid state by #gamma# irradiation of dilute solutions of the parent compounds in the CFCl_3 matrix at 77 K. The ESR parameters of the azetidine radical cation are typical of those for nitrogen-centered amine radical cations such as Me_2NH*"+. On the other hand, the radical cation formed from aziridine has very different ESR parameters that compare closely to those for the isoelectronic C...C ring-opened form of the oxirane radical cation and the allyl radical. The radical cation formed from azetidine is therefore assigned a ring-closed structure with the unpaired electron in a 2p/sub z/ orbital on nitrogen perpendicular to the ring plane, whereas the cation from aziridine is an allylic C...C ring-opened planar ...

46

Protons, heavy ions, radioactive beams: new ways for radiotherapy. Protons, ions lourds, faisceaux radioactifs: de nouvelles voies pour la radiotherapie

The radical cations from aziridine and azetidine have been characterized by ESR spectroscopy following their generation in the solid state by ..gamma.. irradiation of dilute solutions of the parent compounds in the CFCl/sub 3/ matrix at 77 K. The ESR parameters of the azetidine radical cation are typical of those for nitrogen-centered amine radical cations such as Me/sub 2/NH*/sup +/. On the other hand, the radical cation formed from aziridine has very different ESR parameters that compare closely to those for the isoelectronic C...C ring-opened form of the oxirane radical cation and the allyl radical. The radical cation formed from azetidine is therefore assigned a ring-closed structure with the unpaired electron in a 2p/sub z/ orbital on nitrogen perpendicular to the ring plane, whereas the cation from aziridine is an allylic C...C ...

1986-05-22

47

Investigation of the hadronic final state in electron-proton interactions at HERA

In this article, the author presents the principles, applications and advantages of proton and heavy ion beams used for radiotherapy.

1993-07-01

48

Chemiosmotic model for plant mitochondria

The main subject of this thesis is the study of the hardronic final state in deep-inelastic electron-proton scattering. Theexperiment described in this thesis is performed with such a high resolution that the substructure of the proton is probed by the electron beam with a resolution of less than 10{sup -15} cm. (orig./HSI).

1995-09-18

49

Calculation of cosmic ray antiproton-proton ratio

A balanced application of chemiosmosis to plant mitochondria is presented. Electron transport carriers are sequenced to achieve proton translocation across the inner membrane. The processes of proton translocation, use, and release are integrated to yield a description of the effective proton gradient available for metabolite transport and ATP synthesis. 27 references, 6 figures.

1983-12-01

50

Synthesis and characterization of diastereomeric (substituted iminodiacetato)(1,2-diaminocyclohexane)platinum(II) complexes

Cross section parameterizations for antiproton production in pp collisions are used to predict the antiproton/proton ratio resulting from a flux of cosmic protons with energy spectral index of 2.6 interacting with a 5 gm/cm/sup 2/ column density of H. (GHT)

1980-01-01

51

Metal coordination and selectivity with oxine ligands bound to silica polyamine composites

Novel complexes of the type (Pt(DACH)(N-R-iminodiacetate)), wherein DACH represents (R,S)- and (R,R)-1,2 diaminocyclohexane and R represents /minus/Me, /minus/EtOH, and /minus/CH/sub 2/Ph groups, have been prepared, purified, and characterized by spectroscopic techniques (/sup 1/H, /sup 13/C, and /sup 195/Pt NMR;MS(FAB);IR) and by the measurement of selected physical properties (pH, pK/sub a/, conductivity, and molecular weights). The data are consistent with the formation of two diastereomeric complexes in unequal proportions in which the N-R-iminodiacetate ligand appears to be bonded as a pseudofacial tridentate chelate. One are of the ligand forms a stable five-membered-ring O,N-chelate while the other arm appears to be involved in ion-pair formation (zwitterion-like) involving the carboxylate anion and the formally positive Pt(II) central metal atom. It has been demonstrated indirectly that an active impurity was present in predictably inactive bulk complexes ...

1988-11-16

52

British Library Electronic Table of Contents (United Kingdom)

A series of oxine ligands, 5-X, 8 OH C9H6N (X = H, Cl, SO3H) have been covalently bound to a silica gel polyamine composite made from a silanized amorphous silica xerogel and poly(allylamine) (BP-1) by the Mannich reaction. The resulting modified composites WP-4(X = H), CB-1(X = Cl), and SB-1(X = SO3H) were characterized by elemental analysis, FTIR, and solid state CPMAS-13C-NMR. Using the analytical data before and after the ligand modification, the ligand loading could be estimated and in combination with metal ion capacities a metal to ligand ratio could be obtained. The composites WP-4 and CB-1 both showed ratios of approximately 1 : 1 while the sulfonate modified composite, SB-1, showed a metal to ligand ratio of 1 : 2. This is tentatively interpreted in terms of a zwitterionic oxine ...

2010-01-01

53

Yields of Residual Nuclei from Proton-Irradiated Materials

International Science & Technology Center (ISTC)

Experimental and Theoretical Study of the Residual Nuclide Production in 40-2600 MeV Proton-Irradiated Thin Targets of ADS Basic Materials

54

Target stations and beam dumps for the CERN SPS

Electroweak measurements at CDF

The design of the absorber blocks for internal and external dumping of the SPS proton beam is discussed. In addition, the external target stations for slow and fast extracted proton beams are described.

1977-03-16

55

EFFECT OF ANATOMIC MOTION ON PROTON THERAPY DOSE DISTRIBUTIONS IN PROSTATE CANCER TREATMENT

The authors present some recent measurements on electroweak physics using data collected by the CDF experiment at the Tevatron proton anti-proton collider ({radical}s = 1.96 TeV) at Fermilab.

2005-06-01

56

Development of High Field Dipole and High Current Pulse Power Supply for Compact Proton Synchrotron

PurposeTo determine the dosimetric impact of inter-fraction anatomical movements in prostate cancer patients receiving proton therapy.Full Text Available

2007-02-01

57

Antimicrobial activity and mechanism of action of Nu-3, a protonated modified nucleotide

Development of High Field Dipole and High Current Pulse Power Supply for Compact Proton Synchrotron

2003-01-01

58

The reduction of feedwater iron by using absorption characteristics of cation exchange resins for BWR condensate demineralizers

Background"Nubiotics" are synthetic oligonucleotides and nucleotides with nuclease-resistant backbones, and are fully protonated for enhanced ability to be taken up by bacterial...Full Text Available

59

Structure and magnetic properties of the Al1-xGaxFeO3 family of oxides: A combined experimental and theoretical study

Iron concentration control in feedwater is one of the most important subjects in water chemistry. Especially for the BWR plants without 100% flow volume of hollow fiber filter (HFF), rather high iron concentration in feedwater is one of the big issues as this causes relatively high radiation dose rate in drywell area. Cation exchange resins especially used in the plants with partial flow rate of HFF are expected to have the important role of capturing iron in feedwater. For this purpose, we have investigated the effective method for using iron absorption characteristics of cation exchange resin. The Cation-Over Layer method (COL) in condensate demineralizers (CD) effectively utilizes these characteristics. In order to demonstrate a performance of the cation overlay method, we had applied this method for three CD vessels at Fukushima Daiichi NPP Unit 3 for testing purpose. The result of this actual plant ...

2009-10-01

60

Secondary reactions during CO hydrogenation on zeolite-supported metal catalysts: influence of alkali cations

Magnetic properties of the Al1-xGaxFeO3 family of oxides crystallizing in a non-centrosymmetric space group have been investigated in detail along with structural aspects by employing X-ray and neutron diffraction, Moessbauer spectroscopy and other techniques. The study has revealed the occurrence of several interesting features related to unit cell parameters, site disorder and ionic size. Using first-principles density functional theory based calculations, we have attempted to understand how magnetic ordering and related properties in these oxides depend sensitively on disorder at the cation site. The origin and tendency of cations to disorder and the associated properties are traced to the local structure and ionic sizes. -- Graphical abstract: We have studied both experimentally and theoretically the important role of disorder at the cation site on magnetic and related properties of the Al1-xGaxFeO3 family of oxides ...

2011-03-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

61

A fixed cations and low Tg polymer: the poly(4-vinyl-pyridine) quaternized by poly(ethylene oxide) links. Conductivity study; Un electrolyte polymere a cations fixes et bas Tg: les poly(4-vinylpyridine) quaternisees par des chainons de poly(oxyde d`ethylene). Etude de la conductivite

The effect of neutralizing cations on the secondary reactions of the primary products from CO hydrogenation over ion-exchanged zeolite-supported Ru catalysts was investigated using zeolites with different alkali cations (Li/sup +/, Na/sup +/, K/sup +/, Rb/sup +/, Cs/sup +/). The transformation of olefins (propylene and butene) on the zeolites without the metal, under conditions similar to those used for CO hydrogenation, was also studied in order to understand the effect of the various constituents of the support, i.e., the Broensted acid sites generated during catalyst preparation and the alkali cations, on possible secondary reactions of the primary olefinic products. It was established that secondary acid-catalyzed reactions of these primary products can play a major role in shaping product selectivity during CO hydrogenation over zeolite-supported catalysts. Depending on the concentration and the strength of the acid ...

1987-10-01

62

Luminescence of Strontianite (SrCO{sub 3}) from Strontian (Scotland, UK)

The spontaneous ionic polymerization of 4-vinyl-pyridine in presence of mono-tosylated or bromated short chains of poly(ethylene oxide)-(PEO) is used to prepare amorphous comb-like poly-cations with low Tg. The polymer electrolyte properties of these new structures have been studied without any addition of salts. The ionic conductivity of these fixed cation poly-electrolytes depends on the length of the grafted PEO and varies from 10{sup -7} to 10{sup -4} S/cm between 25 and 80 deg. C. It is only weakly dependent on the nature of the cation but it is controlled by the movements of the pyridinium cation which are facilitated by the plastifying effect of the POE chains which do not directly participate to the ionic transport. (J.S.) 17 refs.

1996-12-31

63

The Rational Behavior Model: A Multi-Paradigm, Tri-Level ...

An historic Strontianite-type specimen from Strontian, Scotland, UK, was characterized to broaden our knowledge on luminescence properties of common carbonates. These fibrous aggregates are Strontianite (Sr{sub x}Ca{sub 1-x}CO{sub 3}) with circa 6% of CaO, interfacial water, hydrosilicate anions and substitutional divalent cations, e.g., Ca{sup 2+}, Mn{sup 2+}, Fe{sup 2+} in structural Sr{sup 2+} positions. The specimen was analyzed by X-ray Fluorescence Spectrometry (XRF), Environmental Scanning Electron Microscopy coupled with an Energy Dispersive X-ray Spectroscopy (ESEM-EDS) probe, Spatially-resolved Cathodoluminescence under the Scanning Electron Microscope (SEM-CL), Differential-Thermal Analyses (DTA), Thermogravimetry (TG), Thermoluminescence (TL), Radioluminescence (RL) and High Resolution Spectra Thermoluminescence (3DTL), to gain an overview of the spectral emissions, the defect linkages were modified by heating from room temperature (RT) up to 500 deg. ...

2009-04-15

64

Sorption of astatine cation form by sulfocationite dowex-50x8 from aqueous solutions of perchloric acid

... cations, and precision UUV navigation ... In addition, conventional teleoperation of robots is not ... would involve an autonomous mobile robot capable of ...

1993-03-01

65

Mobilities of CO_2"+ and N_2O"+ in He, Ar and N_2 gases

... adsorption aqueous solutions astatine complexes astatine ions enthalpy organic

66

Complex formation of the At(I) cation with ligands containing donor atoms of the 5th, 6th and 7th main group of the periodic system

... argon carbon dioxide cations electric fields gases helium ion mobility molecular

1976-01-01

67

An investigation on physical properties of strontium hexaferrite nanopowder synthesized by a sol-gel auto-combustion process with addition of cationic surfactant

Published in summary form only.

1991-11-01

68

British Library Electronic Table of Contents (United Kingdom)

In this study a novel sol-gel auto-combustion method, using n-decyltrimethylammonium bromide as a cationic surfactant, has been used to synthesize strontium hexaferrite nanocrystalline powder. The dried nitrate-citrate gel, prepared from a solution of ferric nitrate, strontium nitrate, citric acid, trimethylamine and cationic surfactant, exhibited an auto-combustion behavior after ignition in air. The formation reaction temperature, phase identification, crystallites size, particles size distribution and morphology of resultant strontium hexaferrite powder were investigated by DTA/TGA, FTIR, XRD, LPSA, TEM and SEM techniques. The results showed that in presence of the cationic surfactant, the combustion intensity increases and the crystallite size decreases. The crystallite size of stronti...

2007-01-01

69

Study of the Form Factor of the Proton in the Timelike Region for Large Momentum Transfers

Phenomenological analysis of K{sup +}-meson production in proton-nucleus collisions

No abstract prepared.

2001-01-01

70

Luminosity determination at COSY-11 using the proton-deuteron elastic scattering

No abstract prepared.

2002-03-01

71

Local Quark-Hadron Duality and Magnetic Form Factors of Bound Proton

No abstract prepared.

2002-03-01

72

High energy proton-proton scattering and multiple scattering model including inelastic intermediate states

We discuss the consequence of local duality for elastic scattering, and derive a model-independent equation between structure functions at x ? 1 and elastic electromagnetic form factors. Then the electromagnetic form factors of proton are discussed using the quark-hadron duality theory. We also debate the form factor of proton in a bound state. It may be an effective approach to study the form factor of proton in media.

2005-08-01

73

Elastic proton scattering on neutron rich He isotopes in Glauber approach

The cross sections for proton-proton elastic scattering at Fermilab and ISR energies are investigated in the framework of the multiple constituent scattering formalism, including the contributions of the inelastic intermediate states. We find that the higher-order multiple scattering amplitudes are strongly suppressed due to the presence of the inelastic intermediate states. The calculated cross sections reproduce the high energy experimental data fairly well. (author).

74

Double proton migrations in dimeric methaboric, formic, cis-nitrous and nitric acids

Short communication.

1994-06-20

75

Decay studies of rare-earth isotopes produced in the proton-induced fission

Using ab initio (SCF/6-31G) method, mechanisms of proton migrations in methaboric acid dimers have studied. It is shown that in all the dimers considered a cooperative transfer of protons occurs. The calculated values of activation barriers of cooperative proton transfer reactions in the dimers are equal to 28.6 kcal/mol.

76

Crosslinked sulfonated poly (bis-A)-sulfones as proton exchange membrane for PEM fuel cell application

No abstract prepared

1998-01-01

77

Determination of the initial energy in computerized tomography with proton beams; Determinacao da energia inicial em tomografia computadorizada com feixe de protons

Not Available

2010-02-01

78

#beta#-delayed proton decays near the proton drip line

In earliest works devoted to proton computed tomography it was shown that the advantage of pCT image reconstruction appears when the energy is close to the Bragg peak region, since the proton passes the object. This effect provided by the Bragg peak makes the computerized tomography with protons possible. However, when decreasing the initial proton energy, with the increase of the irradiation dose, there are two effects that work simultaneously in opposite ways. First, the energy loss of a proton in an object becomes bigger at small initial energy. At the same time decreasing of the proton energy results in the increase of the energy straggling, requiring a larger number of protons. In this work the radiation dose dependence on the proton initial energy was studied using analytical formulas and computer simulations. The ...

2007-07-01

79

Use of the 2-Pyridinealdoxime/N,N?-Donor Ligand Combination in Cobalt(III) Chemistry: Synthesis and Characterization of Two Cationic Mononuclear Cobalt(III) Complexes

In order to improve the measuring efficiency, a 'proton-gamma' coincidence technique in combination with a He-jet tape transport system was proposed and employed to identify the #beta#-delayed proton precursors. The study of #beta#-delayed proton decays near the proton drip line by using the 'proton-gamma' coincidence technique over the last 5 years at the Institute of Modern Physics, Lanzhou, China, was summarized. New #beta#-delayed proton precursors "1"2"1Ce, "1"2"5Nd, "1"2"8Pm, "1"2"9Sm, "1"3"5Gd, "1"3"7Gd, "1"3"9Dy, "1"4"2Ho, and "1"4"9Yb in the rare-earth region along a speculated proton drip line were synthesized and identified for the first time. The #beta#-delayed proton decays of "8"1Zr, "8"5Mo, "8"9Ru, and "9"3Pd in T_z=1/2 series as well as "9"2Rh in T_z=1 series were observed.

2002-04-02

80

The opposite effect of bivalent cations on cytochrome b5 reduction by NADH:cytochrome b5 reductase and NADPH:cytochrome c reductase.

The use of 2-pyridinealdoxime (paoH)/N,N′-donor ligand (L-L) “blend” in cobalt chemistry has afforded two cationic mononuclear cobalt(III) complexes of the general type [Co(pao)₂(L-L)]⁺,...Full Text Available

2010-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

81

Stable halogen complexes of astatine cations in aqueous solutions

The effects of bivalent cations on cytochrome b5 reduction by NADH:cytochrome b5 reductase and NADPH:cytochrome c reductase were studied with the proteinase-solubilized enzymes. Cytochrome b5 reduction...Full Text Available

1988-05-01

82

Protective Effects of a Human 18-Kilodalton Cationic Antimicrobial Protein (CAP18)-Derived Peptide against Murine Endotoxemia

Halide complexes of astatine cations At"+ and AtO"+ were prepared and their rate of migration was measured. The complexes are of the type AtX_2"- and AtOX_2"- (X = Cl"-, Br"-, I"-). The bromo complexes, AtBr_2"- and AtOBr_2"-, have a higher stability than the chloro complexes. The hydrolysis in weakly alkaline solution of AtX_2"- resulted At"-, and that of AtOX_2"- AtO_2"-. (author).

83

NHE8 is an intracellular cation/H⁺ exchanger in renal tubules of the yellow fever mosquito Aedes aegypti

CAP18 (an 18-kDa cationic antimicrobial protein) is a granulocyte-derived protein that can bind lipopolysaccharide (LPS) and inhibit various activities of LPS in vitro. The present study examined the...Full Text Available

1998-05-01

84

Cation exchange separation of trace amounts of {sup 203}Hg and {sup 181}Hf

The goal of this study was to identify and characterize the hypothesized apical cation/H⁺ exchanger responsible for K⁺ and/or Na⁺ secretion in...Full Text Available

2009-04-01

85

NAME=\\

Wastenet

... Electro-Osmotic Pulse (EOP) technology forces moisture to flow through concrete surfaces against the hydraulic gradient when an electric field is applied to an embedded anode system. This flow is initiated by the movement of cations (positively charged ions) present in a porous medium such as concrete toward the negative earth. Water surrounding the cations moves with them. The Corps of Engineers owns and maintains many buried ...

86

Treatment of radioactive liquid waste by reverse osmosis; Influence of co-existing ions on the change of decontamination factor

A radiochemical method of separation of {sup 203}Hg from {sup 181}Hf is described. The method involves separation by Dowex 50W- X 8, 100-200 mesh, cation exchange resin using 1 M hydrochloric acid as the eluant. The chemical yield for the separation of mercury is > 85% and the decontamination factor is >10{sup 4}. The {sup 181}Hf can be eluted from the column by 4 M HCl.

2000-02-01

87

Treatment of radioactive liquid waste by reverse osmosis

The report addresses the application of reverse osmosis to the treatment of radioactive liquid waste, focusing on the effects of non-radioactive cations and anions, existing in radioactive waste, on the removal of radioactive nuclides. The bivalent cations are generally about ten times as high in decontamination factor as monovalent ones. In the case of anions, the factor of SO{sub 4}{sup 2-} is about ten times that of Cl{sup -} while that of NO{sub 3}{sup -} is somewhat smaller than that of Cl{sup -}. During permeation through membrane, anions tend to accompany cations, and the decontamination factor of accompanying ions is found to increase with that of the paring ions. These results indicate that if one can select components that will remain in the liquid waste, one should consider their effects on the efficiency of its treatment. Furthermore, the interaction between two anions or between two cations ...

1991-01-01

88

Steady-state passive films; Interfacial kinetic effects and diagnostic criteria

The report addresses the application of reverse osmosis to the treatment of radioactive liquid waste, focusing on the effects of non-radioactive cations and anions, existing in radioactive waste, on the removal of radioactive nuclides. The bivalent cations are generally about ten times as high in decontamination factor as monovalent ones. In the case of anions, the factor of SO_4"2"- is about ten times that of Cl"- while that of NO_3"- is somewhat smaller than that of Cl"-. During permeation through membrane, anions tend to accompany cations, and the decontamination factor of accompanying ions is found to increase with that of the paring ions. These results indicate that if one can select components that will remain in the liquid waste, one should consider their effects on the efficiency of its treatment. Furthermore, the interaction between two anions or between two cations can be approximated by a ...

89

Meson production in proton-proton collisions in the naive non-abelianization approximation and the role of infrared renormalons

This paper reports that the point defect model for steady-state passive films formed anodically on metal s in aqueous environments has been extended to include irreversible dissolution of the film and the irreversible generation and annihilation of cation and oxygen vacancies at the metal/film and film/solution interfaces. THe model yields a number of diagnostic criteria that can be used to identify the majority (vacancy) charge carrier and to characterize the kinetic nature of the interfacial vacancy generation and annihilation processes. We use these criteria to show that the steady-state passive film that forms on nickel in acidic phosphate buffer solutions is a cation conductor and that cation transport from the metal to the solution involves irreversible ejection of cations from the film. On the other hand, the passive film that forms on tungsten in the same environment under steady-state ...

1992-01-01

90

Morphology, structure, and conductivity of polypyrrole prepared in the presence of mixed surfactants in aqueous solutions

In this article, we investigate the "naive non-abelianization" (NNA) contributions of the higher-twist Feynman diagrams to the large-$p_T$ inclusive pion production cross section in proton-proton collisions and present the general formulae for the higher-twist differential cross sections in the case of the running coupling and frozen coupling approaches. We compared the resummed "naive non-abelianization" higher-twist cross sections with the ones obtained in the framework of the frozen coupling approach and leading-twist cross section. The structure of infrared renormalon singularities of the higher twist subprocess cross section and it's resummed expression (the Borel sum) are found. It is shown that the resummed result depends on the choice of the meson wave functions used in the calculations. We discuss the phenomenological consequences of possible higher-twist contributions to the meson production in proton-proton collisions in within NNA ...

2011-01-01

91

British Library Electronic Table of Contents (United Kingdom)

Polypyrrole (PPy) was prepared from different mixed-surfactant solutions with ammonium persulfate as an oxidant. Three types of combinations were selected, including cationic/anionic, cationic/nonionic, and anionic/nonionic mixed-surfactant solutions. The surfactants used in the experiments included cetyltrimethylammonium bromide (cationic surfactant), sodium dodecyl sulfate (anionic surfactant), sodium dodecyl sulfonic acid salt (anionic surfactant), poly(vinyl pyrrolidone) (nonionic surfactant), and poly(ethylene glycol) (nonionic surfactant). The morphology, structure, and conductivity of the resulting PPy were investigated in detail with scanning electron microscopy, Fourier transform infrared spectra, and the typical four-probe method, respectively. The results showed that the interac...

2007-01-01

92

Gamma irradiation induced damage creation on the cation distribution, structural and magnetic properties in Ni-Zn ferrite

Development of anion-exchange resins for separations of actinides

Ferrite of system, namely Ni_1_-_xZn_xFe_2O_4 with x = (0.0, 0.2, 0.4, 0.6, 0.8, 1.0), have been prepared by solid state reaction to investigate the effect of gamma rays irradiations using Co"6"0 source on the cation distribution, structural and magnetic properties. The unirradiated and irradiated samples were then subjected to characterization techniques such as X-ray diffraction, magnetization and AC susceptibility. The results of these characterizations are found to be different for irradiated from that of the pristine sample. The modifications in respect of irradiated samples are explained in terms of the ion-induced disorder. The important result of #gamma#-irradiation on the cation distribution, structural and magnetic properties is the change of ratio Fe"2"+/Fe"3"+. Possible reasons on the results are proposed.

2010-09-01

93

As-synthesized MCM-41 silica: new adsorbent for perchlorate

The evolution of these new ion-exchange resins hinges upon an understanding of the chemistry of actinide metal complexes as they exist in solution and when interacting with the cationic sites. Molecular modeling of electrostatic interactions between the metal complex and the cationic substrate is used to help visualize uptake mechanisms and, eventually, to predict optimized coordination sites. Thus, these new materials integrate the fields of ion-specific chelation and ion-exchange technology. Synthesized resins contain cationic sites designed to facilitate the uptake of plutonium nitrato complexes from high-nitrate solutions, and they exhibit distribution coefficients that are up to 10 times higher than those observed for commercial resins. Additionally, some new resins show surprisingly large Kd`s for anionic complexes of Am(III) and U(VI).

1997-12-31

94

British Library Electronic Table of Contents (United Kingdom)

Here we demonstrate that the as-prepared MCM-41 mesoporous silica material, which is synthesized using cetyltrimethylammonium bromide as a cationic surfactant exhibits very high capacity for perchlorate uptake from solutions. Thus we discover a new function for the as-synthesized mesoporous materials containing cationic surfactants. These materials are shown to have better capacity than the currently used activated carbon, which is preloaded with cationic surfactant. As-synthesized MCM-41 has a higher removal of perchlorate with 0.378???0.038?meq/g than the surfactant modified activated carbon sample, which removed 0.304???0.005?meq/g i.e., MCM-41 has a 24 % higher capacity than the surfactant modified activated carbon sample for perchlorate uptake because of higher surfactant content and ...

2010-01-01

95

Estimating the stabilities of aqueous actinide complexes with sulfoxy-anions

Water Molecule Contributions to Proton Spin-Lattice Relaxation in Rotationally Immobilized Proteins

Full text of publication follows: Stable aqueous sulfur species are mainly sulfide (H{sub 2}S) and sulfate (SO{sub 4}{sup 2-}) ions. However, several sulfoxy-anions may be detected as metastable anions in natural environment, as typically thiosulfate (S{sub 2}O{sub 3}{sup 2-}) and sulfite (SO{sub 3}{sup 2-}) ions [1]. In natural systems, uranium speciation and migration are mainly governed by carbonate complexes in non reducing conditions. Whereas sulfate is already known as a complexing agent of actinides, data relating to U-SO{sub 3}{sup 2-} and U-S{sub 2}O{sub 3}{sup 2-} complexes have only been proposed for U(VI) [2], but are usually not included in thermodynamic databases [3]. Therefore, it appears to be relevant to determine complexation constants of actinides with sulfur ligands, for RN migration studies, concerning nuclear waste disposal as well as migration behaviour in the geosphere. In the present study, values have been estimated for the first complexing constants of U{sup ...

2005-07-01

96

Range and modulation dependencies for proton beam dose per monitor unit calculations

Spin-lattice relaxation rates of protein and water protons in dry and hydrated immobilized bovine serum albumin were measured in the range of ¹H Larmor frequency from 10 kHz to 30...Full Text Available

2009-07-01

97

Pairing effects in nucleon transfer reactions in the system sup 144 Sm+ sup 88 Sr at 4. 7 MeV/u

Calculations of dose per monitor unit (D∕MU) are required in addition to measurements to increase patient safety in the clinical practice of proton radiotherapy. As in conventional photon and...Full Text Available

2009-02-01

98

Pairing effects in nucleon transfer reactions in the system "1"4"4Sm+"8"8Sr at 4.7 MeV/u

Proton and neutron transfer populating low-lying states have been studied in the system {sup 144}Sm+{sup 88}Sr at an energy below the Coulomb barrier. The experimental cross sections for the single proton transfer are well reproduced by DWBA-calculations using spectroscopic information from light ion reactions. The two-proton transfer appears enhanced relative to the uncorrelated sequential transfer of single protons. The same holds for the transfer of proton pairs, the enhancement is kept for the second pair. This is interpreted as a supercurrent between two superfluid nuclear proton-pair wave functions: More mass and charge is transported per time unit in pairs than by single nucleons. Neutron transfer is observed with large cross sections and is found to contribute to the energy loss observed in the transfer reactions. For mixed ...

1990-05-01

99

Multiplicity distribution of charged particles in cosmic-ray proton induced nuclear reaction

Proton and neutron transfer populating low-lying states have been studied in the system "1"4"4Sm+"8"8Sr at an energy below the Coulomb barrier. The experimental cross sections for the single proton transfer are well reproduced by DWBA-calculations using spectroscopic information from light ion reactions. The two-proton transfer appears enhanced relative to the uncorrelated sequential transfer of single protons. The same holds for the transfer of proton pairs, the enhancement is kept for the second pair. This is interpreted as a supercurrent between two superfluid nuclear proton-pair wave functions: More mass and charge is transported per time unit in pairs than by single nucleons. Neutron transfer is observed with large cross sections and is found to contribute to the energy loss observed in the transfer reactions. For mixed proton-neutron ...

100

Intravenous proton pump inhibitors for peptic ulcer bleeding: Clinical benefits and limits

The measured result of charged multiplicity in cosmic-ray proton induced nuclear reaction from Chinese satellite emulsion is reported. The correlation of shower and heavy particles is discussed and compared with p-emulsion interactions.

1993-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

101

Crystallographic structure of xanthorhodopsin, the light-driven proton pump with a dual chromophore

Peptic ulcer bleeding is a common disease and recurrent bleeding is an independent risk factor of mortality. Infusion with proton pump inhibitors (PPIs) prevents recurrent bleeding after successful...Full Text Available

2011-03-16

102

Analysis of data on cumulative antiproton production by 10-GeV protons

Homologous to bacteriorhodopsin and even more to proteorhodopsin, xanthorhodopsin is a light-driven proton pump that, in addition to retinal, contains a noncovalently bound carotenoid with a function...Full Text Available

2008-10-28

103

Study of physical properties of protons and "1"2C ions in medical application

The data are analyzed on cumulative antiproton production on Be, Al, Cu, and Ta nuclei induced by 10 GeV protons. The analysis is carried out in the framework of the flucton quark fragmentation model.

104

Spectra of protons produced in 24 MeV alpha particle interactions with "6"4Zn

Depending on their unique physical properties, proton and heavy ions have taken an irreplaceable role in modern means of tumor treatment. One-step process and two-step process physical models were employed to explain the mechanism of ion energy loss. The transport process of proton and "1"2C in water was simulated by Geant4 toolkit to study the physical properties of ion beam. The calculation results were discussed, which showed the advantages and disadvantages of proton and "1"2C in the medical application. (authors)

2009-06-01

105

Solar neutrinos, solar flares, solar activity cycle and the proton decay

Short note. 1 ref.; 1 tab.

1989-04-18

106

Role of the #DELTA#(1232)-resonance at the systematic reduction of magnetic isovector transitions

It is shown that there may be a correlation between the galactic cosmic rays and the solar neutrino

1985-01-01

107

Proton production in the kinematically forbidden region

... electron reactions electrons excitation inelastic scattering m1-transitions proton

108

Preparation of "2"0"3Pb compounds for studies on pathway and effects of lead pollution

Proton production in pA interactions in the kinematically forbidden region is studied using the intranuclear cascade model for the primary proton energies 7.5 and 8.9 GeV/c. The region of secondary-proton kinetic energies above 100 MeV, where the contribution from the post-cascade stages of the interaction is small, is studied. The calculated energy and angular spectra are in good agreement with the experimental ones. The mechanisms of multiple rescattering of particles on the nucleons of the nucleus and ..pi..-meson absorption on a two-nucleon flucton are analyzed. The kinematical ranges where these mechanisms operate are determined.

1985-08-01

109

Polarized proton acceleration at the Brookhaven AGS

... air pollution coprecipitation isotope production lead 203 proton beams

110

Nuclear structure physics at high resolution

At the conclusion of polarized proton commissioning in February 1986, protons with an average polarization of 45%, momentum of 21.7 GeV/c, and intensity of 2 x 10/sup 10/ protons per pulse, were extracted to an external polarimeter at the Brookhaven AGS. In order to maintain this polarization, five intrinsic and nearly forty imperfection depolarizing resonances had to be corrected. An apparent interaction between imperfection and intrinsic resonances occurring at very nearly the same energy was observed and the correction of imperfection resonances using ''beat'' magnetic harmonics discovered in the previous AGS commissioning run was further confirmed.

1986-01-01

111

Neutron escape from isobaric analogue resonances

Techniques for studying nuclear structure are reviewed. Examples are given of charge density determinations by electron and proton inelastic scattering. (AIP)

1985-04-01

112

Model-independent analysis of the neutron-proton final-state interaction region in the pp{yields}pn{pi}{sup +} reaction

... level widths mev range 01-10 neutrons nuclear reactions proton beams

113

Evidence at the 10/sup -18/ probability level against the production of magnetic monopoles in proton interactions at 300 GeV/c

No abstract prepared.

2002-03-01

114

Evaluation of the residual radiation field in the proton accelerator facility of the Proton Engineering Frontier Project (PEFP) in Korea

No magnetic monopoles were found in 2.5*10/sup 18/ primary proton- aluminium interactions produced by exposing an aluminium target to the Fermilab 300 GeV/c proton beam. Negative searches have also resulted from exposures of material to electrons at SLAC and from pp interactions at the CERN-ISR. The monopole pair production probability in proton-nucleon collisions is shown to be of order 10/sup -18/ or less, with 95% confidence level, if monopoles have masses less than 12 GeV. (24 refs).

1975-01-01

115

British Library Electronic Table of Contents (United Kingdom)

In Korea, the Proton Engineering Frontier Project (PEFP) is building a proton linear accelerator facility with energy up to 100MeV and a beam current of 20mA. In this study, a radiation field after shutdown in the accelerator facility of the PEFP was evaluated for the purpose of the radiation shielding by using MCNPX code. A facility modeling was performed for the accelerator tunnel building, accelerator chain, target rooms and beam experiment hall. And radiation source terms were evaluated in the facility. With this facility, model and radiation source terms, the concentration of 41Ar was evaluated and the cooling time satisfying regulation in Korea was calculated.

2007-01-01

116

Emission of light charged particles accompanying uranium fission induced by 153-MeV protons

Differential Diagnosis of Brain Diseases Using In Vivo Proton Magnetic Resonance Spectroscopy at 3 Tesla: A Preliminary Study

The emission of light charged particles from heavy fragments of uranium fission induced by 153-MeV protons is studied. The probability of their emission is 2.7 x 10{sup - 2} per fission event. It is found that these particles affect the distribution of angles of fragment divergence and the angular distribution of heavy fragments with respect to the primary-proton beam. Experimental results suggest that the preequilibrium emission of particles is correlated with fission. Two mechanisms of interaction between 153-MeV protons and uranium nuclei are considered. 13 refs., 10 figs., 1 tab.

1995-12-01

117

KoreaScience (Korea)

Full Text Available

2009-12-01

118

APOD: 2000 July 18 - A Russian Proton Rocket Launches Zvezda

"2"0"3Pb yields while irradiating thallium with protons and deuterons

is launched from the Baikonur Cosmodrome in Kazakstan. Tomorrow's picture: A Galactic Whirlpool ...

2011-10-07

119

The proton microprobe: Applications in the biomedical field

... data deuteron beams energy dependence errors gamma radiation lead 203

120

The NuMI proton beam at Fermilab successes and challenges

This book explores the development, present, and future applications of proton microprobes in the micrometer range. Among the topics discussed: the use of proton beams for analytical purposes; techniques of focusing or collimating ion beams; improving and measuring beam spots; the analytical capabilities of the nuclear microprobe in comparison to other micro techniques; and applications and results by several internationally known microprobe laboratories.

1986-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

121

Risk assessment for heavy ions of parts tested with protons

The NuMI beam at Fermilab has delivered over 5 x 10{sup 20} 120 GeV protons to the neutrino production target since the start for MINOS [1] neutrino oscillation experiment operation in 2005. We report on proton beam commissioning and operation status, including successes and challenges with this beam.

2008-11-01

122

Proton beam therapy for cancer in deep-seated organs

An internuclear cascade-evaporation code is used to model energy deposition in thin slabs of silicon. This model shows that protons produce a significant number of events with effective Linear Energy Transfer (LET) greater than 8 MeV cm"2/mg and demonstrates that proton testing of microelectronic components can be an effective way to screen devices for low earth orbit susceptibility to heavy ions.

1997-12-01

123

Production of "2"0"3Pb by proton irradiation of Bi

Radiation therapy has shown definite technical improvement due to application of proton beam irradiation. Clinical results of proton beam therapy also suggested enlargement of indication ranges in radial treatment and decrease of post radiation damages of the treatment of cancers in deep-seated organs. Inprovement of result in cancer therapy could be expected by this treatment technique in the future.

1988-10-01

124

Neutron-proton mass difference in isospin-asymmetric nuclear matter

Production of lead-203 by proton irradiation of bismuth metal has been investigated as a replacement method for commercially available lead-203. Targets of bismuth metal (0.1 cm thick) were irradiated for periods of 1-3 hours with 90 MeV protons. After processing of the target, the estimated yield of lead-2-3 was 30 millicuries/microamp.

1990-06-24

125

Absorbed dose and dose equivalent depth distributions for protons with energies from 2 to 600 MeV

Isospin-breaking effects in the baryonic sector are studied in the framework of a medium-modified Skyrme model. The neutron-proton mass difference in infinite, asymmetric nuclear matter is discussed. In order to describe the influence of the nuclear environment on the skyrmions, we include energy-dependent charged and neutral pion optical potentials in the s- and p-wave channels. The present approach predicts that the neutron-proton mass difference is mainly dictated by its strong part and that it strongly decreases in neutron matter. (orig.)

2007-06-15

126

Transitions between distinct compaction regimes in complexes of multivalent cationic lipids and DNA

Depth dose distributions for protons in the energy range from 2 to 600 MeV have been calculated by Monte Carlo and analytical methods. The dependence on energy of Maximum Dose Equivalent (MDE), quality factor and isotropic factor recommended for practical use are presented. The problems connected with regulation of maximum permissible proton fluxes are discussed. (author).

1989-01-01

127

Targeted gene transfection from microbubbles into vascular smooth muscle cells using focused, ultrasound-mediated delivery

We use X-ray scattering and molecular simulations to investigate the structural properties of complexes of multivalent cationic lipids and DNA molecules. At low mole fraction of neutral lipids (NLs), $\\Phi_{\\rm NL}$, the complexes show dramatic DNA compaction down to essentially close packed DNA arrays with a DNA interaxial spacing $d_{\\rm DNA}=25\\AA$. A gradual increase in $\\Phi_{\\rm NL}$ does not lead to a continuous increase in $d_{\\rm DNA}$ as observed for DNA complexes of monovalent cationic lipids (CLs). Instead, distinct spacing regimes exist, with sharp transitions between them. Three packing states have been identified: (i) close packed, (ii) condensed, but not close packed, with $d_{\\rm DNA}=27-28\\AA$, and (iii) an expanded state, where $d_{\\rm DNA}$ increases gradually with $\\Phi_{\\rm NL}$. Based on our experimental and computational results, we conclude that the DNA condensation is mediated by the multivalent ...

2008-01-01

128

On the Uptake of Materials by the Intact Liver THE CONCENTRATIVE TRANSPORT OF RUBIDIUM-86

We investigate a method for gene delivery to vascular smooth muscle cells using ultrasound triggered delivery of plasmid DNA from electrostatically coupled cationic microbubbles. Microbubbles...Full Text Available

2010-09-01

129

Metal cation inhibitors for controlling denting corrosion in steam generators. Final report. [PWR

In this study we use the multiple indicator dilution technique to outline the kinetic mechanisms underlying the uptake of rubidium, a cation which, in the steady state, is concentrated by hepatic parenchymal...Full Text Available

1973-05-01

130

Investigations into the nature of a silicoaluminophosphate with the faujasite structure

Metal cations of arsenic, antimony, tin, manganese, zinc, cadmium, indium, and thallium have been evaluated in a preliminary way as possible3 inhibitors for controlling denting corrision observed in steam generators used with pressurized water reactors (PWR). The rationale for this approach was based upon the well-known inhibition effects of metal cations on corrosion rates in electrolyte/metal systems. A review of corrosion inhibition by metal cations (H. Leidheiser, Jr., Corrosion 36, 339 (1982)) has identified eleven inhibition mechanisms. The major test methods used for this evaluation were: (1) Isothermal capsule tests of carbon/steel/Inconel 600 tube bulging rates at temperatures up to 288/sup 0/C in seawater/copper-nickel chloride bulge-accelerating solutions. (2) Immersion weight-loss tests of steel coupled to Inconel 600 in boiling (102/sup 0/C) 3% sodium chloride solutions. In addition, electrochemical measuremens ...

1982-12-01

131

Interactions of metal cations with anionic groups on the cell Wall of the macroalga vaucheria sp.

The physicochemical nature of a silicoaluminophosphate with the faujasite structure has been studied. The molecular sieve framework contains a homogeneous distribution of silicon, aluminum, and phosphorus and is negatively charged. Combustion in air of the charge-compensating organic cations produces hydroxyl groups which exhibit Broensted acidity.

1987-04-29

132

Improvement of leaching characteristics of TOC from condensate demineralizers

The aim of this article was to investigate the interactions of metal cations in aqueous solutions with the biomass of the freshwater macroalga Vaucheria sp. This problem is important when elaborating new applications of biosorption, e.g. the production of mineral feed additives for livestock from the biomass of algae enriched with microelement ions. Potentiometric titration was applied as a quick and cheap screening test to search for new efficient biosorbents. It revealed a variety of functional groups capable of cation exchange on the macroalgal surface, including carboxyl, phosphate, hydroxyl or amino groups. Fourier transform infrared spectroscopy on natural and chromium-loaded Vaucheria sp. confirmed that carboxyl groups played a dominant role in the biosorption. The study also showed that Ca(II), Na(I), K(I), and Mg(II) ions were released from the biomass after biosorption of Cu(II), Mn(II), Zn(II), and Co(II) ions, indicating that ion ...

2010-06-15

133

Hydrogen bonding and perhalometallate ions: A supramolecular synthetic strategy for new inorganic materials

Recent nuclear power plants require high purity water to protect nuclear reactors or steam generators from SCC and maintain in good condition. In this connection, it is especially important to minimize sulfate, which is a corrosive chemical originated from oxidative degradation of cation exchange resins during operation. Recently, uniform particle size (UPS) strong acid cation gel resin with 14% cross-linkage, which has excellent stability against oxidization, has been applied to several condensate purification systems. For further improvement of water quality, some methods for changing the configuration of condensate demineralizer's resin bed have been examined. For example, these methods correspond to anion under layer and cation over layer. We have tested these methods by cold column tests. Furthermore, we have developed the newly anion exchange resin having higher efficiency and capacity for absorbing leachables from ...

2009-10-01

134

Effects of Multivalent Cations on Cell Wall-Associated Acid Phosphatase Activity

A synthetic strategy for constructing ionic hydrogen-bonded materials by combining perhalometallate anions with cations able to serve as hydrogen bond donors is presented. The approach is based on identification...Full Text Available

2002-04-16

135

Detection by /sup 125/I-cationized cytochrome c of proteoglycans and glycosaminoglycans immobilized on unmodified and on positively charged nylon 66

Primary cell walls, free from cytoplasmic contamination were prepared from corn (Zea mays L.) roots and potato (Solanum tuberosum) tubers. After EDTA treatment, the...Full Text Available

1988-09-01

136

Cationic nanoparticles for delivery of amphotericin B: preparation, characterization and activity in vitro

We have examined the detection by a /sup 125/I-labeled basic protein, cationized cytochrome c, of selected proteoglycans (PGs) and standard preparations of glycosaminoglycans (GAGs) immobilized on Nylon 66 and also on positively charged Nylon 66. Immobilization on Nylon 66 appears to allow a relative freedom of interaction between PGs or GAGs and /sup 125/I-cationized cytochrome c, but a more restricted reaction was observed when PGs and GAGs were immobilized to positively charged Nylon 66. On this support PGs with large numbers of GAG side chains reacted well with /sup 125/I-cationized cytochrome c, but GAGs were minimally reactive. By taking advantage of some of the properties of large-pore agarose-acrylamide gels, rapid partial characterization of some PGs can be accomplished in the 10-ng range, and therefore at a sensitivity equal to PGs with internal biosynthetic labels.

1987-09-01

137

Cation Involvement in Telomestatin Binding to G-Quadruplex DNA

BackgroundParticulate systems are well known to be able to deliver drugs with high efficiency and fewer adverse side effects, possibly by endocytosis of the drug carriers. On the...Full Text Available

138

The fluorescence properties and NMR analysis of protopine and allocryptopine

The binding mode of telomestatin to G-quadruplex DNA has been investigated using electrospray mass spectrometry, by detecting the intact complexes formed in ammonium acetate. The mass measurements show...Full Text Available

139

Stabilisation of #alpha#-Sialons using multiple additives

The fluorescence properties of protopine and allocryptopine in aqueous and organic environments are described for the first time. The fluorescence of alkaloids and their pH-dependent interconversion to cationic forms (transannular interaction) were studied using steady-state and time-resolved fluorescence techniques. For the analysis of tricyclic base and cis/trans tetracyclic cations of the alkaloids, NMR and X-ray crystallography were used. - Highlights: ? We describe fundamental fluorescence characteristics of alkaloids protopine and allocryptopine. ? We analyzed the pH-dependent transitions and cis/trans isomerization. ? These two alkaloids can be better distinguished by their fluorescence decay characteristics. ? The fluorescence parameters are related to the NMR and crystallographic structural data.

2011-07-01

140

One-electron oxidation of photosynthetic pigments in micelles. Bacteriochlorophyll a, chlorophyll a, chlorophyll b, and pheophytin a

Multi-cation #alpha#-Sialon ceramics were prepared using mixtures of samarium with calcium, magnesium, yttrium and ytterbium, and compared with a pure Sm-Sialon of equivalent total stabilising cation composition. A ratio of 80eq% samarium to 20eq% of the second stabilising additive was used. Samples were fired at 1820 deg C and subsequently heat treated at 1450 deg C. XRD phase analysis showed that all additives resulted in greater #alpha#-Sialon stability, and that calcium was the most effective additive for the stabilisation of the #alpha#-Sialon phase. Copyright (1998) Australasian Ceramic Society

1998-09-28

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141

Fragmentation and ion-molecule reaction of diethylmercury radical cations: an ESR study in irradiated frozen freon matrices and spin trapping in liquid phase

Chlorophyll a, chlorophyll b, and bacteriochlorophyll a in aqueous micellar solutions of Trition X 100 (2%) are readily oxidized by pulse-radiolytically generated N_3., Br_2"-., and (SCN)_2"-. radicals at nearly diffusion-controlled rates. The kinetic study suggests that pigment molecules occupy multiple sites in the micelle. Pheophytin a is only oxidized by N_3. and Br_2"-. radicals. The absolute spectra and the molar extinction coefficients of chlorophyll a, bacteriochlorophyll a, chlorophyll b, and pheophytin a cations have been determined. The chlorophyll a cation has been observed in the presence of pigment aggregates.

1981-11-01

142

Adsorption of ammonia and pyridine on copper(II)-doped magnesium-exchanged smectite clays studied by electron spin resonance

The mono- and intramolecular cation-radicals (CR) reactions of diethylmercury in the CFCl_3, CFCl_2CF_2Cl matrices and CF_2BrCF_2Br and CFCl_3 freons vitrified mixture (1:1) were studied through the EPR method. Formation of radical products of transformations of the initial CR diethylmercury (X-ray radiation dose - 100-200 Gy at the temperature of 293 K) was studied through the spin trap of 2.4.6 - tri-tret-butylnitrosebenzene.

143

Proton-proton scattering above 3 GeV/c

The interaction between N-donor adsorbates such as ammonia and pyridine with Cu(II)-exchanged montmorillonite, beidellite, flourohectorite into smectite clays has been studied by electron spin resonance. Cu(II) cations exchanged into smectites coordinate five ammonia or pyridine molecules in beidellite, four ammonia of pyridine molecules in hydroxyhectorite. Thus, the Cu(II) cations bound to the interior surfaces of these smectite clays constitute strong Lewis acid sites. 26 refs., 7 figs., 1 tab.

1993-01-14

144

Particle emission from low energy proton bombardment of TiH{sub 2} and TiD{sub 2}

A large set of data on proton-proton differential cross sections, analyzing powers and the double-polarization parameter A{sub NN} is analyzed employing the Regge formalism. We find that the data available at proton beam momenta from 3GeV/c to 50GeV/c exhibit features that are very well in line with the general characteristics of Regge phenomenology and can be described with a model that includes the {rho}, {omega}, f{sub 2}, and a{sub 2} trajectories and single-Pomeron exchange. Additional data, specifically for spin-dependent observables at forward angles, would be very helpful for testing and refining our Regge model. (orig.)

2010-09-15

145

Long-term mortality and cancer risk in irradiated rhesus monkeys. Interim report, 30 September 1983-15 July 1989

TiH{sub 2} and TiD{sub 2} thick targets were bombarded with 100 to 200 keV protons. Evidence for nuclear reactions was obtained by means of a surface barrier particle detector. Proton irradiation of TiD{sub 2} produced the following observations: {alpha} particle emission identified as (p, {alpha}) reactions from {sup 11}B and {sup 7}Li impurities in the target at ppm concentrations; and {approx}3 MeV proton and {approx}1 MeV triton emission from secondary D-D reactions caused by elastic scattering of the primary proton with a target deuteron. A 3.9 MeV {alpha} particle peak measured by others was not observed. (author)

2002-03-01

146

Inelastic proton scattering as a mean for the determination of neutron and proton matrix element ratios

Lifetime observations on a group of 358 rhesus monkeys indicate that life expectancy loss from exposure to protons in the energy range encountered in the Van Allen belts and solar proton events is influenced primarily by the dose rather than the energy of radiation. After 24 years, life expectancy losses from similar surface doses of low-LET (138-2300 MeV) and high-LET (32-55 MeV) protons are not significantly different, but the high-LET protons are associated with more deaths in the early years, while the low-LET protons contribute more to mortality in later years. In males, the most significant cause of life shortening is nonleukemia cancers.

1990-05-01

147

Inelastic proton scattering as a mean for the determination of neutron and proton matrix element ratios

The determination of ratio of neutron over proton matrix elements by inelastic proton scattering, for 0{sup +}{yields}2{sup +} transitions, is investigated via the comparison between experimental data and theoretical calculations. Calculations into the context of a macroscopic and a microscopic description are performed for a wide mass range nuclei: {sup 18}O, {sup 30}Si, {sup 32,34}S, {sup 48}Ca, {sup 88}Sr, for which these ratios were determined previously with an independent technique. At that point the choice of the theoretical model may be very critical. It is thus the purpose of this investigation to point out the most suitable model. It is found that in general both theoretical models can be employed for the reliable determination of neutron over proton matrix element ratios.

1999-12-06

148

Exploring the potential energy surface for proton transfer in acetylacetone

The determination of ratio of neutron over proton matrix elements by inelastic proton scattering, for 0"+#->#2"+ transitions, is investigated via the comparison between experimental data and theoretical calculations. Calculations into the context of a macroscopic and a microscopic description are performed for a wide mass range nuclei: "1"8O, "3"0Si, "3"2","3"4S, "4"8Ca, "8"8Sr, for which these ratios were determined previously with an independent technique. At that point the choice of the theoretical model may be very critical. It is thus the purpose of this investigation to point out the most suitable model. It is found that in general both theoretical models can be employed for the reliable determination of neutron over proton matrix element ratios.

1999-12-06

149

Comparison of LAHET code system calculations with experimental results for protons of energies less than 50 MeV incident on copper and iron

The portion of the potential energy surface (PES) of acetylacetone relevant for the intramolecular proton transfer reaction is studied using ab initio and DFT methods. The best estimate of the barrier governing proton transfer was found to be 3.4 kcal mol{sup -1} at the MP4(FC)/6-311 + G(2d,2p)//MP2(FC)/6-311 + G(2d,2p) level of theory. Six stationary points on the PES were characterized as well as the reaction paths connecting these points. Special attention paid to the pathway of intramolecular proton transfer reveals that the internal rotation of the methyl group adjacent to the carbonyl group and the proton transfer reaction are consecutive processes.

2004-11-15

150

A compensating method of an imaging plate response to clinical proton beams

The LAHET code system calculations and experimental results for proton interactions with an energy <50 MeV are compared. For these energies, the theories behind the LAHET models are not applicable. Three quantities compared are (a) the magnitude of the neutron yield generated through proton interactions, (b) the energy and angular distributions of the resultant neutrons, and (c) the residual nuclei produced by proton interactions (spallation products). The comparisons are for protons incident on iron and copper, except in the case of the energy and angular distributions, which are calculated only for iron. The neutron yields predicted by LAHET agree with published measurements to within 50% for both materials. For iron, the predicted energy and angular distributions agree to within a factor of 3. Finally, the predicted spallation product yields of both materials agree with measurements to within a ...

1997-03-01

151

Effect of Collimation Slit and Shield Thickness in a Prompt Gamma-based Proton Beam Range Measurement System

For charged particle irradiations, the response of an imaging plate (IP) changes around the Bragg peak. Therefore, an appropriate compensation is necessary for the evaluation of dose distribution formed by charged particles such as protons. In this paper, the response of IPs to clinical proton beams is investigated. An experimentally-obtained depth-dose distribution (an ordinary Bragg curve) by a silicon semiconductor detector (SSD) is employed to evaluate the compensation factors as a function of proton penetrating depth, i.e. residual range. A typical dose distribution in a water phantom formed by an L-shaped bolus is measured by IPs and corrected by using the information of those compensation factors; the residual proton range is successfully calculated by the pencil beam algorithm at an arbitrary point. The results show a good agreement with the measurements by the SSD within the rms error of 3.0%.

2002-04-01

152

Sorption equilibrium and hydration studies of lysozyme: water activity and 360-MHz proton NMR measurement

The proton beam has a unique advantage over the electron and photon beams in that it can give very high radiation dose to the tumor volume, while effectively sparing the neighboring healthy tissue and organs. For the clinical application of the proton beam, it is very important to confirm the location of the proton beam in the patient, preferentially during the treatment. It has been suggested that the range of the proton beam in the patient can be determined by measuring prompt gammas from the proton beam passage. Recently, a prototype prompt-gamma scanning system has been constructed and tested using experimental and therapeutic proton beams. The measurement results for the proton beams of 70 . 230 MeV showed that a clear correlation exists between the distribution of the prompt gammas and the proton beam range. The ...

2007-07-01

153

Rare-earth doped (#alpha#'/#beta#')-sialon ceramics

An attempt to determine lysozyme hydration by employing a proton nuclear magnetic resonance (NMR) spin-echo technique and to correlated such measurements with the 20 "0C sorption equilibrium data is made. Determinations of specific site hydration for lysozyme, as well as proton NMR transverse relaxation rates for five different types of water populations in the lysozyme-water system, are presented over the whole range of lysozyme concentrations. The proton spin-echo NMR results are consistent with a three-component analysis of the sorption isotherm up to 70% water content, above which two additional water populations are identified by 360-MHz proton NMR spin-echoes. On the basis of the proton NMR results, a major component (III) of the lysozyme sorption isotherm is assigned to the water trapped between lysozyem molecules, whose relaxation rate is increased by diffusion barriers. The ...

154

Soil chemistry and nutrition of North American spruce-fir stands: Evidence of recent change

The objectives of this research were to investigate the possibility of controlling the #alpha#'/#beta#' phase ratio and morphology in Sialon ceramics. These objectives have been sought by the control of the starting composition, and by post sintering heat treatment. The main emphasis has been on the production of a series of #alpha#' and (#alpha#'+#beta#') Sialon ceramics with a minimum amount of the glass phase by the pressureless sintering technique and using ytterbium (Yb) as an #alpha#' stabilising element. The Yb additions were made via the oxide or the alumino- silicate presynthesised glass; the latter was found to improve the density. The XRD analysis of the as sintered materials revealed #alpha#' to be the dominant phase with minor contributions from #beta#' sialon and/ or 12H A1N polytype. Additions of SiO_2 or #beta#-Si_3N_4 were made to various materials to assess potential mechanisms for obtaining control over the microstructural development of #alpha#'/#beta#' sialon ...

155

Characterization of tris(N-substituted-2-methyl-3-hydroxy-4-pyridinonato)technetium(IV) cations

One set of hypotheses offered to explain the decline of red spruce (Picea rubens Sarg.) in eastern North America focuses on the effect of acidic deposition on soil chemistry changes that may affect nutrient availability and root function. Long-term soils data suggests that soil acidification has occurred in some spruce stands over the past 50 yr, with plant uptake and cation leaching both contributing to the loss of cations. Studies of tree ring chemistry also have indicated changes in Ca/Al and Mg/Al ratios in red spruce wood, suggesting increases in the ionic strength of soil solution. Irrigation studies using strong acid inputs have demonstrated accelerated displacement of base cations from upper horizons. Spruce-fir (Abies spp.) nutrient budgets indicate that current net Ca and Mg leaching loss rates are of the same order of magnitude as losses to whole tree harvest removals, spread out over a 50-yr rotation. For most ...

156

Characterization of tris(N-substituted-2-methyl-3-hydroxy-4-pyridinonato)technetium(IV) cations

A burgeoning interest in technetium coordination chemistry has been spurred by its widespread use in nuclear medicine. Recent focus has been on the design and preparation of new technetium complexes, the lipophilicity, polarity, and overall charge of which can be readily altered by simple substitutions in the molecular framework of the ligand in order to optimize the biodistribution and target specific organs. Examples are cationic (Cardiolite) and neutral (Ceretec) technetium complexes, used as myocardial and brain imaging agents, respectively. The authors have been pursuing a continuing study of tris(3-hydroxy-4-pyridinonato)gallium and -indium complexes that are water soluble, are hydrolytically stable, and are of varying lipophilicity and neutral charge. Studies of in vivo in rabbits and mice have revealed that several of these cationic complexes may be useful as morphologic kidney imaging agents, with [{sup 99m}Tc(pap){sub 3}]{sup +} ...

1994-11-23

157

Measurement of W and Z production cross sections with the ATLAS experiment at sqrt(s) = 7 TeV

A burgeoning interest in technetium coordination chemistry has been spurred by its widespread use in nuclear medicine. Recent focus has been on the design and preparation of new technetium complexes, the lipophilicity, polarity, and overall charge of which can be readily altered by simple substitutions in the molecular framework of the ligand in order to optimize the biodistribution and target specific organs. Examples are cationic (Cardiolite) and neutral (Ceretec) technetium complexes, used as myocardial and brain imaging agents, respectively. The authors have been pursuing a continuing study of tris(3-hydroxy-4-pyridinonato)gallium and -indium complexes that are water soluble, are hydrolytically stable, and are of varying lipophilicity and neutral charge. Studies of in vivo in rabbits and mice have revealed that several of these cationic complexes may be useful as morphologic kidney imaging agents, with ["9"9"mTc(pap)_3]"+ showing elevated ...

158

Atomistic Simulation of Water Percolation and Proton Hopping in Nafion Fuel Cell Membrane

W and Z bosons are expected to be produced abundantly at the Large Hadron Collider (LHC). This large dataset and the high LHC energy will allow for detailed studies of their properties in a previously unexplored kinematic domain of low parton momentum fraction and high energy scale thus providing, together with the proton-proton nature of the collisions, new constraints on the parton distribution functions and precise tests of perturbative QCD. First determinations of the W -> lnu and Z -> ll (l = e,mu) production cross sections for proton-proton collisions at sqrt(s) = 7 TeV were performed using about 320/nb of data recorded by the ATLAS experiment at the LHC. The results of these measurements for W and Z bosons for proton-proton collisions at sqrt(s) = 7 TeV are presented. In addition ?rst measurements of the ratio between the W and Z/gamma*-cross sections and of the W -> lnu charge asymmetry are also ...

2011-01-01

159

Activation of Polymethyl-Methacrylate by Proton Beam

We have performed a detailed analysis of water clustering and percolation in hydrated Nafion configurations generated by classical molecular dynamics simulations. Our results show that at low hydration levels H2O molecules are isolated and a continuous hydrogen-bonded network forms as the hydration level is increased. Our quantitative analysis has established a hydration level (?) between 5 and 6 H2O/SO3- as the percolation threshold of Nafion. We have also examined the effect of such a network on proton transport by studying the structural diffusion of protons using the quantum hopping molecular dynamics method. The mean residence time of the proton on a water molecule decreases by two orders of magnitude when the ? value is increased from 5 to 15. The proton diffusion coefficient in Nafion at a ? value of 15 is about 1.1x10-5 cm2/s in agreement with experiment. The results provide quantitative ...

2010-11-04

160

Two-proton excitations at the Z=38 and Z=40 sub-shell closures

Activation has been used for many kinds of useful applications, such as use of the radioisotopes for diagnosis and treatment of cancer, and wear (or corrosion) investigation for using thin layer activation (TLA) technique, etc. But activation also has severe problems for the post-processing of the samples; such as time-loss, inconvenience of sample handling, personal radiation safety, etc. For in-vitro experiments, we observed death of tumor cells by proton irradiation. The use of large activated container material can cause erroneous results in this case. To solve these problems, we studied why the samples were activated and how the level of the activation could be reduced. In proton beam irradiation experiments, the target materials could be defined as the container and sample itself. We could easily reduce activation of container material comparing to activation of sample itself. Therefore, we tried to find less activated container material ...

2010-10-01

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161

The identification of the 1/2"+[660] proton orbitals at high spins in rare-earth nuclei

The "8"6Kr("3He,n)"8"8Sr and "8"8Sr("3He,n)"9"0Zr reactions were studied to determine whether significant excited 0"+ strength was observed or whether these nuclei exhibited absence of excited state strength generally seen away from shell closures. Various properties of the levels are considered including angular distributions, spins, parities, interference, and enhancement. It is concluded that neither "8"8Sr nor "9"0Zr exhibit the strong proton pairing vibration expected for a closed proton shell nucleus.

1977-11-01

162

The CTOF measurements and Monte Carlo analyses of neutron spectra for backward direction from iron target irradiated by protons with energies from 400 to 1200 MeV

Decay sequences based on the 1/2"+[660] proton orbital have been identified in "1"7"1Ta and "1"7"7Re based on spin, parity, and large alignment. This decay sequence is observed higher in energy than predicted in cranking calculations based on modified oscillator potentials. Similarly known 1/2"-[541] decay sequences in these and other neighbouring isotopes are observed lower in energy than predicted. A reduction in the strength of the spin-orbit potential for protons is suggested as a solution to these problem. (orig.).

163

Recovery of radioactive thallium isotopes from lead and bismuth targets irradiated by 1-GeV protons

A calorimetric-time-of-flight (CTOF) technique was used for real-time, high-precision measurement of neutron spectrum at the angle of 175 degrees from the initial proton beam direction, which hits a face plane of a cylindrical iron target of 20 cm in diameter and 25 cm thick. A comparison was performed between the neutron spectra predicted by the MARS and the MCNPX code systems and measured by experiments for 0.4-, 0.6-, 0.8-, 1.0-, and 1.2-GeV protons.

2009-01-01

164

Recovery of radioactive thallium isotopes from lead and bismuth targets irradiated by 1-GeV protons

A simple highly efficient procedure has been developed for recovery of thallium radioisotopes from lead and bismuth targets irradiated by 1-GeV protons. The procedure is based on the use of extraction chromatography. The cross-sections have been determined for formation of {sup 200}Pb, {sup 201}Pb, {sup 202m}Pb, and {sup 203}Pb radioisotopes in targets from lead with natural isotopic composition, irradiated by 1-GeV protons.

1995-03-01

165

Proton beam monitoring and forming on the target of isotope complex at INR linac

A simple highly efficient procedure has been developed for recovery of thallium radioisotopes from lead and bismuth targets irradiated by 1-GeV protons. The procedure is based on the use of extraction chromatography. The cross-sections have been determined for formation of "2"0"0Pb, "2"0"1Pb, "2"0"2"mPb, and "2"0"3Pb radioisotopes in targets from lead with natural isotopic composition, irradiated by 1-GeV protons.

166

Possible processes of abiogenic synthesis of biologically important compounds on surface of small bodies in the Solar System

Special beam extraction channel is used at INR linac for isotope production. It starts from 160 MeV measuring and matching area of accelerator. This choice of beam extraction enables to direct to the target of isotope complex a proton beam of wide energy range up to 160 MeV. It is important for production of different types of nuclides. The measuring results of proton beam behavior in this region are presented. Required beam forming in 160 MeV measuring and matching area of accelerator and in beam extraction channel is discussed.

2010-01-01

167

Polarizing a stored proton beam by spin flip?

A mixture of aminoacids was irradiated by a scattered proton beam, its energy varying from 4 to 6.6 MeV, by doses up to 5 x 10"1"1 proton/cm"2 for studying the potentiality of abiogenic synthesis of biologically important compounds in space. It was ascertained that increase in the radiation dose and reduction of proton energy involve increase in effectiveness both of destruction of the initial aminoacid (tryptophan, tyrosine, glycine) and synthesis of the relevant dipeptide. Essential influence of mineral substrate on abiogenic synthesis of natural nucleotides under the action of diverse energy sources was pointed out

2004-04-01

168

Phenomenological dirac optical potential for neutron cross sections

We discuss polarizing a proton beam in a storage ring, either by selective removal or by spin flip of the stored ions. Prompted by recent, conflicting calculations, we have carried out a measurement of the spin-flip cross section in low-energy electron-proton scattering. The experiment uses the cooling electron beam at COSY as an electron target. The measured cross sections are too small for making spin flip a viable tool in polarizing a stored beam. This invalidates a recent proposal to use co-moving polarized positrons to polarize a stored antiproton beam.

2009-04-27

169

Performance of the transition radiation detector flown on the NMSU/WIZARD TS93 balloon-borne instrument

Because of limitation on neutron-incident data, it is difficult to obtain global optical model potential for neutrons. In contrast, there are some global optical model potentials for proton in detail. It is interesting to convert the proton-incident global optical potentials into neutron-incident ones. In this study we introduce (N-Z)/A dependent symmetry potential terms into the global proton-incident optical potentials, and then obtain neutron-incident ones. The neutron potentials reproduce total cross sections in an acceptable degree. However, a comparison with potentials proposed by other authors brings about a confused situation in the sign of the symmetry terms. (author).

1997-03-01

170

Optical properties of proton-irradiated polymers

It is built and tested a transition radiation detector (TRD) to discriminate positrons from protons in the balloon flight TS 93 experiment. It is presented the TRD performance using flight data obtaining a proton-positron rejection factor of the order of 10{sup -3}. During the 24 hour flight, the data in the momentum range 4-50 GeV/c are collected. Using the TRD together with the Silicon calorimeter, it is achieved an overall rejection factor of about 10{sup -5} of positron against the proton background over the entire momentum range.

1995-09-01

171

NuMI proton beam diagnostics and control: achieving 2 megawatt capability

Recently, organic semiconducting materials have gained a broad interest due to their potential for organic electronic devices such as organic light emitting diode (OLED), organic photovoltaic devices and organic field-effect transistors (OFETs). Optical properties of organic semiconducting materials are important for practical application. For example, the power conversion efficiency of organic photovoltaic devices is mainly affected by absorption properties of organic materials. Proton irradiation is one of the efficient methods to change the optical properties of organic materials. In this paper, we investigate the changes of optical properties of various polymers using the proton irradiation.

2009-05-15

172

Ion beam analysis of high temperature superconducting samples

The NuMI proton beam at Fermilab currently delivers 120 GeV protons to the neutrino production target with design beam power capability to 400 kW. Upgrade capability to 700 kW is being prepared, with planning toward delivering 2.3 MW beam provided by the Project X accelerator upgrade plan. We report on the system of beam diagnostics and control used in operation of the NuMI beam. Also considered are the steps to provide a robust system for transport and targeting beam of 2 MW and beyond.

2008-10-01

173

Identification of the 1/2/sup +/(660) proton orbitals at high spins in rare-earth nuclei

Characterization of high temperature superconducting film and bulk samples has been carried out using 2 MeV [alpha]-particle Rutherford backscattering, 2.4 MeV proton elastic scattering, 2.4 MeV proton-induced x-ray emission, 9 MeV proton induced [gamma]-ray emission and 100 MeV iodine elastic recoil detection analysis techniques. The objective was to compare different ion beam based techniques for: (i) compositional analysis; and (ii) consistency of the results obtained for samples prepared using similar preparation methodology. (author).

1994-02-01

174

Feasibility study on the development of proton accelerator

Decay sequences based on the 1/2/sup +/(660) proton orbital have been identified in /sup 171/Ta and /sup 177/Re based on spin, parity, and large alignment. This decay sequence is observed higher in energy than predicted in cranking calculations based on modified oscillator potentials. Similarly known 1/2/sup -/(541) decay sequences in these and other neighbouring isotopes are observed lower in energy than predicted. A reduction in the strength of the spin-orbit potential for protons is suggested as a solution to these problem.

1983-12-08

175

A traveling wave direct energy converter for a D-"3He fusion reactor

A feasibility on the development of a high energy proton accelerator to be used for R and D in the nuclear field of korea was studied. The proposed one is a proton linac with parameters of about 1 GeV, 20 mA which can supply enough neutrons by the spallation reaction to drive a subcritical reactor. It= is expected to solve the intrinsic problem in the nuclear field such as safety, nuclear waste, proliferation and resource. The study was carried out through a multi-institutional cooperation of universities, institute and industry for a national consensus. 5 refs., 8 tabs., 8 figs. (author)

1996-10-01

176

(/sup 3/He,n) reaction in the Aapprox. =100 region

A concept of a traveling wave direct energy converter (TWDEC) is developed for 14.7-MeV fusion protons based on the principle of a backward wave oscillator. Separation of fusion protons from thermal ions is accomplished by using ExB ion drift. Energy conversion rate up to 0.87 is attained by applying three-stage modulation of the proton beam. A one-dimensional particle-circuit code is developed to examine self-excitation of the traveling wave and its stability under loading. Electrostatic wave with a fixed frequency is excited spontaneously, and stability of the wave is ensured under loading. (author).

177

Zero-motion flucton correlations and high-energy proton elastic scattering on "4"0Ca

The available experimental data on the (/sup 3/He,n) reaction between the ground states of even-even nuclei and lowest 1/2/sup -/ levels of odd-A nuclei in the Aapprox.=100 region are analyzed in a systematic way by the DWBA. The deduced relative intensities of these two-proton transfers, and their uncertainties, are compared to the predictions of various nuclear models. In particular, the influence of the finite dimension of the configuration space available to the transferred protons, and of the blocking effect of a 2p1/2/sup -/ proton, are examined. (orig.).

1986-03-01

178

W-7405 - NASA Technical Report Server (NTRS)

1984. p. I37. Germany Antonov, AN Christov, CV Petkov, IZ Bylgarska

179

Unified semi-microscopic description of low-energy proton and. alpha. -particle scattering by nuclei

W. Wayne Scott and R. G. Alsmiller, Jr. ABSTRACT. Comparisons of the results obtained for a hypothetical problem with four different proton penetration ...

180

Theoretical Standard Model Rates of Proton to Neutron Conversions Near Metallic Hydride Surfaces

We develop the formalism of a unified semi-microscopic description of low-energy proton and {alpha}-particle interaction with nuclei. We analyze elastic and inelastic proton scattering at the energy 25.05 MeV and {alpha}-particle scattering at the energy 104 MeV by the {sup 90}Zr nucleus. Information is obtained on differences in the deformation of the proton and neutron distributions. We study the energy dependence of the semi-microscopic {alpha}-particle potential including the energy dependence of the potential geometry.'' We analyze the change in angular distributions of elastically scattered {alpha} particles with increase of energy and the contribution to the scattering cross section from nucleon-nucleon correlations.

1989-07-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

181

Proton spectra from 54.8-MeV alpha-particle reactions: precompound emission

The process of radiation induced electron capture by protons or deuterons producing new ultra low momentum neutrons and neutrinos may be theoretically described within the standard field theoretical model of electroweak interactions. For protons or deuterons in the neighborhoods of surfaces of condensed matter metallic hydride cathodes, such conversions are determined in part by the collective plasma modes of the participating charged particles, e.g. electrons and protons. The radiation energy required for such low energy nuclear reactions may be supplied by the applied voltage required to push a strong charged current across a metallic hydride surface employed as a cathode within a chemical cell. The electroweak rates of the resulting ultra low momentum neutron production are computed from these considerations.

2006-01-01

182

Proton emission in reaction of 14.6 MeV neutrons with natural iron

(Dec 1973). United States Chevarier, A. Chevarier, N. Demeyer, A.

183

Particle emission from low energy nuclear reactions in solids. Preliminary results

The energy spectra and angular distributions of proton emission in a reaction of {sup nat}Fe(n,xp) at a neutron energy of 14.6 MeV are measured by the University of Science and Technology of China multitelescope system. The double-differential cross sections of 16 reaction angles from 25 to 164.5 deg are obtained in this measurement. The statistical errors are reduced largely because of the thick target used. The angular distributions show a slightly energy-dependent forward-backward asymmetry. The angle-integrated proton spectrum is compared with theoretical calculations and other results. The total proton-emission cross section is in fair agreement with the prediction and evaluation.

1996-01-01

184

Mechanical jacks meant to support the movable shielding wall (Proton Room side) of the SC

TiH{sub 2} and TiD{sub 2} thick targets were bombarded with 100 to 200 keV protons or deuterons. Evidence for nuclear reactions was obtained by means of a surface barrier particle detector. Deuteron irradiation of TiD{sub 2} produced these observations: copious {approx}2.5 MeV neutrons and {approx}3 MeV protons from direct D-D reactions; gamma rays from p,{gamma} and n,{gamma} reactions; {approx}14 MeV protons from the secondary d({sup 3}He, p){alpha} reaction; and a signal between {approx}6-12 MeV that Kasagi et al. has tentatively identified as protons from the fusion of three deuterium nuclei. However, this signal has in it a strong interference signal from either neutrons or gamma rays that directly deposit energy in the detector. This interference spectra was measured by placing a thick absorber in front of the detector that stops up to 20 MeV protons, but not gamma rays or ...

2000-07-01

185

Isotopic dependence of emission of protons produced in the approximately 24 MeV #alpha#-particle interaction with Ni isotopes

This mechanical version was soon after changed into a hydraulic jack one (the reason being a number of serious constructional defects).

1955-01-01

186

Intermediate structure in the minimum of the excitation function of protons elastically scattered from "8"8Sr around 12.5 MeV

Russian 1986. p. 329. USSR Smirnov, AV Antropov, AE Zarubin, PP

1986-04-15

187

Facilitated Proton Transfer by a Novel 2-Aminothiazole Derivative Across the Water/1,2-Dichloroethane Interface

... functions intermediate structure isobaric analogs level widths mev range

1973-08-27

188

British Library Electronic Table of Contents (United Kingdom)

The behavior of proton transfer facilitated by a novel thiazole derivative, N-methyl-4-(4-phenoxyphenyl)thiazol-2-amine (MPPT), across the water/1,2-dichloroethane (1,2-DCE) interface was investigated electrochemically. The ionic partition diagram for MPPT was obtained from interpretation of the cyclic voltammograms. The apparent partition coefficient of MPPT was evaluated by the shaking-flask method under experimental conditions, while that for the protonated form of MPPT was calculated from its transfer potential obtained from the ionic partition diagram. It was suggested that the mechanism for transfer of MPPT across the water/1,2-DCE) interface depends on the pH of the aqueous phase. The parameters of the facilitated proton transfer across the water/1,2-DCE interface were evaluated as ...

2011-01-01

189

Energy and angular distributions of neutrons from 90-MeV proton and 140-MeV alpha-particle bombardment of nuclei

Energy and angular distributions of neutrons from 90-MeV proton and 140-MeV alpha-particle bombardment of nuclei

Neutron time-of flight spectra were measured from 90 MeV protons and 140 MeV alpha-particle bombardment of Al, Ni, Zr, and Bi at laboratory angles between 20/sup 0/ and 130/sup 0/. The proton induced neutron spectra reveal three distinct energy regions; a low energy evaporation region, a high-energy region dominated by quasi-free scattering processes and an intermediate-energy region dominated by multi-step, pre-equilibrium processes. In the latter two regions, the spectra show strong angular dependence. The alpha-induced neutron spectra show these same distinct energy regions plus an exponential fall-off above the beam energy per nucleon. The high-energy portions of the forward-angle neutron and proton cross sections are in ratios consistent with the assumption that single nucleon-nucleon scattering dominates. For heavy-mass targets, the low-energy evaporation regions show neutron yields larger than ...

1982-01-01

190

Energy and angular distributions of neutrons from 90 MeV proton and 140 MeV alpha-particle bombardment of nuclei

Neutron time-of flight spectra were measured from 90 MeV protons and 140 MeV alpha-particle bombardment of Al, Ni, Zr, and Bi at laboratory angles between 20"0 and 130"0. The proton induced neutron spectra reveal three distinct energy regions; a low energy evaporation region, a high-energy region dominated by quasi-free scattering processes and an intermediate-energy region dominated by multi-step, pre-equilibrium processes. In the latter two regions, the spectra show strong angular dependence. The alpha-induced neutron spectra show these same distinct energy regions plus an exponential fall-off above the beam energy per nucleon. The high-energy portions of the forward-angle neutron and proton cross sections are in ratios consistent with the assumption that single nucleon-nucleon scattering dominates. For heavy-mass targets, the low-energy evaporation regions show neutron yields larger than proton ...

191

Electric and magnetic dipole transitions in odd-proton rare-earth nuclei

We measured neutron time-of-flight spectra from 90 MeV protons and 140 MeV alpha particles bombarding thin targets of Al, Ni, Zr, and Bi at laboratory angles between 20_0 and 135_0. The low-energy (5 to 45 MeV) portions of the spectra were measured with 5 cm diameter by 5 cm deep NE-213 counters at 1 m flight paths with n-#betta# pulse-shape discrimination. The high-energy (35 to 150 MeV) portions of the spectra were measured with 12.7 cm diameter by 10.2 cm deep NE-102 counters at flight paths of 2.0 to 5.0 m. The proton-induced measured neutron spectra reveal three distinct energy regions: a low-energy evaporation region, a high-energy region dominated by the quasifree scattering process, and an intermediate-energy region dominated by multistep, preequilibrium processes. In the latter two regions, the spectra show strong angular dependence. The alpha-particle induced neutron spectra show these same distinct energy regions plus an exponential ...

192

Effect of decrease of molybdenum radiation hardening at high energy proton irradiation

... gamma cascades kev range 10-100 lifetime lutetium 171 lutetium 173 lutetium

1972-05-01

193

Durability of Membrane Electrode Assemblies (MEAs) in PEM Fuel ...

By method of transmission electron microscopy and measuring of microhardness the peculiarities of influence of radiation defect clusters on molybdenum radiation hardening along range path of protons with 30 MeV initial energy are studied. Decrease effect of hardening growth value and even its absence depending on irradiation dose in the range of 10-20 MeV proton energies in presence of high density of radiation defect dispersed clusters is revealed. It is shown experimentally that this effect is connected with accumulation of hydrogen up to not very high concentrations (not more than 5x10"-"4 at.%) at the expense of elastic and inelastic proton scattering. 5 refs.; 5 figs.

1990-05-22

194

Double decoupling and pseudo-spin alignment

Proton exchange membrane (PEM) fuel cells are energy sources that have the ... for H2 /02 PEM fuel cells because their catalysts have properties suitable for 0 ...

195

Double decoupling and pseudo-spin alignment

Doubly decoupled structures in doubly odd deformed nuclei are reexamined and shown to be composed of a pseudo-spin aligned neutron and a decoupled proton. (orig.).

1992-04-16

196

Deep-level defects and numerical simulation of radiation damage in GaAs solar cells

Doubly decoupled structures in doubly odd deformed nuclei are reexamined and shown to be composed of a pseudo-spin aligned neutron and a decoupled proton. (orig.).

197

Copper deficiency alters the neurochemical profile of developing rat brain

A review of the deep-level defects observed in both electron- and proton-irradiated GaAs solar cells is presented. Studies of the effects of periodic and continuous thermal annealing on the radiation-induced electron and hole traps and the recombination parameters in GaAs solar cells were made for a wide range of electron and proton energies, fluence, annealing temperature and annealing time. A refined model for numerical simulations of the displacement damage was developed for computing the defect density and the cell parameters in the electron- and proton-irradiated GaAs solar cells. Excellent agreement was obtained between the calculated values and the experimental data for the proton-irradiated GaAs solar cells. (orig.).

1991-09-01

198

Characteristics of wave-particle interaction in a hydrogen plasma

Copper deficiency is associated with impaired brain development and mitochondrial dysfunction. Perinatal copper deficiency was produced in Holtzman rats. In vivo proton NMR...Full Text Available

2009-06-01

199

Transient diffusion, desorption, and reaction studies of cyclopropane and propylene with NaX and Eu/NaX zeolites

We study the characteristics of cyclotron wave-particle interaction in a typical hydrogen plasma. The numerical calculations of minimum resonant energy Emin, resonant wave frequency ?, and pitch angle diffusion coefficient D?? for interactions between R-mode/L-mode and electrons/protons are presented. It is found that Emin decreases with ? for R-mode/electron, L-mode/proton and L-mode/electron interactions, but increase with ? for R-mode/proton interaction. It is shown that both R-mode and L-mode waves can efficiently scatter energetic (10 keV-100 keV) electrons and protons and cause precipitation loss at L=4, indicating that perhaps wave-particle interaction is a serious candidate for the ring current decay. (authors)

2008-09-01

200

The phospholipid vesicles coating on metal chelated inorganic surfaces

The exchange of Eu[sup 3+] for Na[sup +] cations into the sodalite cages of X zeolite (Eu[sub 25]Na[sub 11]X) leads selectively to the isomerization reaction of cyclopropane to propylene. The latter reaction is catalyzed by Broensted acid sites with an apparent activation energy of 10.6 kcal/mol. Sorption measurements of cyclopropane and propylene with Eu/NaX and NaX zeolites at 40 C support the view that Na[sup +] cations might be considered as sites for sorption of these molecules. Force fields created by Eu[sub 4]O[sup 10+] present in Eu/NaX zeolite may affect sorption. On the other hand, Broensted acid sites in Eu/NaX enhance sorption of cyclopropane and propylene at 40 C. Chemisorption of propylene on the Broensted acid sites of Eu/NaX is reversible and may occur via a propylene carbenium cation intermediate. Small amounts of hexene are formed during this sorption. The amount of Broensted acid sites in the present ...

1992-05-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

201

Support effects on CO hydrogenation over Ru/zeolite catalysts

This work showed the formation of phospholipid vesicle coating on inorganic sericite surface with characterization by combining electron microscopy of FE-SEM, TEM, AFM, and qualitatively evaluated the coated phospholipid vesicle by XPS as a function of etching time. The possibility of phospholipid vesicle mobility on the surface was restrained by the chelation effect of magnesium cation. The stabilization properties of phospholipid vesicles on sericite surface were demonstrated by the various concentration of magnesium cation. The presence of magnesium was found to have a much more pronounced influence on the lipid deposition process. The Mg cation plays an important role for attaching the phospholipids with optimum concentration of 7 mM. Totally, the phospholipid vesicles coating on inorganic powder could be useful for bio-related fields such as cosmetics and drug delivery system as the key functional compounds. We hope ...

2007-09-01

202

Stability and cations coordination of DNA and RNA 14-mer G-quadruplexes: a multiscale computational approach.

Hydrogenation of carbon monoxide at 101.3 kPa has been studied over a series of ion-exchanged Ru catalysts supported on NaX, NaY, KL, Na mordenite, and HY zeolites. The type of zeolite had pronounced effects on the activity and selectivity of the Ru. The specific activity would appear to be related to the dispersion of reduced ruthenium in the zeolite. Methane selectivity, however, seems to be strongly influenced by the type and concentration of alkali cations remaining in the ion-exchanged zeolite. These cations appear to promote chain growth much as traditional alkali promoters would, though perhaps more indirectly. Due to bifunctional properties of the zeolite-supported catalysts, a significant fraction of C/sub 4/ was in the form of isobutane. Formation of isobutane seems to be related to either the Si/Al ratio in the zeolites or the concentration of the remaining alkali cations, but not to the OH concentration. In ...

1984-02-01

203

Solid electrolyte and lithium battery employing it. Kotai denkaishitsu oyobi sore wo shiyo shite naru richiumu denchi

Molecular dynamics simulations have been used to study the differences between two DNA and RNA 14-mer quadruplexes of analogous sequences. Their structures present a completely different fold: DNA forms a bimolecular quadruplex containing antiparallel strands and diagonal loops; RNA forms an intrastrand parallel quadruplex containing a G-tetrad and an hexad, which dimerizes by hexad stacking. We used a multiscale computational approach combining classical Molecular dynamics simulations and density functional theory calculations to elucidate the difference in stability of the 2-folds and their ability in coordinating cations. The presence of 2'-OH groups in the RNA promotes the formation of a large number of intramolecular hydrogen bonds that account for the difference in fold and stability of the two 14-mers. We observe that the adenines in the RNA quadruplex play a key role in conserving the geometry of the hexad. We predict the cation ...

2008-09-03

204

Propagation of an alkaline wave with a short contact time through an argilite sample from the Meuse-Haute Marne underground laboratory; Propagation d'une onde alcaline a temps de contact court a travers un echantillon d'argilite de l'est

Recently, the lithium ion-conductive solid electrolyte draws attention because there is a possibility of producing the maintenance-free battery which is characterized by having such advantages as high energy density and no possibility of electrolyte leak because of solid state structure. The invented lithium ion-conductive solid electrolyte is formed by sintering the granular electrolyte expressed in the following general formula: Li(1+(4-n)x)MxTi(2-x)(PO4)3 (M = mono- or di-valent cation, x = 0.1 - 0.5). Examples of the monovalent cation are Na[sup +], K[sup +], Rb[sup +], Cs[sup +], and Cu[sup +]. Examples of divalent cation are Mg[sup 2+], Fe[sup 2+], Be[sup 2+], Ca[sup 2+], Sr[sup 2+], Ba[sup 2+], Ra[sup 2+], Mn[sup 2+], Co[sup 2+], Cu[sup 2+], Ni[sup 2+], Zn[sup 2+], and Cd[sup 2+]. The electric conductivity of lithium ion is increased with the increase in the content of Li[sup +] in the electrolyte. 4 figs.

1993-11-12

205

Nanoheterostructure Cation Exchange: Anionic Framework Conservation

In the framework of the feasibility study of radioactive waste disposal in deep geologic formations, a clay formation (named 'argilite de l'Est') has been selected in the Meuse-Haute Marne region (France) for the construction of an underground laboratory. The percolation of alkaline solutions through the argilite has been studied using column experiments with short residence times (30 min). These experiments simulate the leaching of a cement which could be used in the building materials of the laboratory. The alkaline solutions used are mono-cationic solutions of calcium, sodium and strontium. The behaviour of calcium is differentiated from the other cations. For all alkaline solutions (NaOH, Ca(OH){sub 2} or Sr(OH){sub 2}) chemical reactions consuming both hydroxide ions and their associated cations have been evidenced. These reactions are heterogenous reactions of surface adsorption by site ...

2001-07-01

206

Grain boundary segregation of cation dopants in {alpha}-Al{sub 2}O{sub 3} scales

In ionic nanocrystals the cationic sub-lattice can be replaced with a different metal ion via a fast, simple, and reversible place-exchange, allowing post-synthetic modification of the composition of the nanocrystal, while preserving its size and shape. Here, we demonstrate for the first time that during such an exchange, the anionic framework of the crystal is preserved. When applied to nanoheterostructures, this phenomenon ensures that compositional interfaces within the heterostructure are conserved throughout the transformation. For instance, a morphology composed of a CdSe nanocrystal embedded in a CdS rod (CdSe/CdS) was exchanged to a PbSe/PbS nanorod via a Cu2Se/Cu2S structure. During every exchange cycle, the seed size and position within the nanorod were preserved, as evident by excitonic features, Z-contrast imaging, and elemental line-scans. Anionic framework conservation extends the domain of cation exchange to the design of more ...

2010-05-11

207

Crystalline and Liquid Crystalline Organic-Inorganic Hybrid Salts with Cation-Sensitized Hexanuclear Molybdenum Cluster Complex Anion Luminescence

A Fe-20at.%Cr-10%Al matrix was dispersed with a wide range of different oxides in order to study the effect of oxygen-active dopants on the high-temperature growth and adhesion of {alpha}-Al{sub 2}O{sub 3} scales. Effect of these various cation dopants on the alumina scale microstructure was correlated with dopant ion segregation to the {alpha}-Al{sub 2}O{sub 3} grain boundaries using analytical electron microscopy. Elements such as Mn and V showed little effect on the oxide scale and were not observed to segregate. Elements such as Y and Gd resulted in finer, more columnar {alpha}-Al{sub 2}O{sub 3} grains and were segregated to scale grain boundaries. However, Ti, Ta, Ca, and Nb also were found to segregate but had a lesser effect on scale morphology. This indicates that cation segregation to scale grain boundaries is not a sufficient condition to achieve beneficial oxidation effects. The driving force for segregation in growing alumina scales ...

1996-12-31

208

British Library Electronic Table of Contents (United Kingdom)

Abstract The salts [Cnmim]2[Mo6Cl14] (mim = methylimidazolium; n = 4, 6, 12, 16, 18) have been obtained by reaction of CnmimCl with MoCl2. Thermal analysis shows the melting point decreases with increasing alkyl chain length of the cation. The imidazolium chloromolybdates(II) with n = 6-18 decompose above 340 C; [C18mim]2[Mo6Cl14] is thermally stable up to 390 C. All compounds are insensititve to the constituents of the atmosphere. Of the higher melting salts [Cnmim]2[Mo6Cl14] (n = 4, 6), high-quality single crystals could be obtained. Single-crystal X-ray structural analyses clearly show that the cluster complex anion [Mo6Cl14]2- has an electron-precise octahedral {Mo6} cluster. For [C4mim]2[Mo6Cl14], two polymorphs differing in the cation alkyl-side-chain conformation were obtained. The ...

2011-01-01

209

Charged species in the radiolysis of supercritical CO{sub 2}

Interaction of antimicrobial peptides with lipid membranes

The pulse radiolysis technique has been employed in studying charge-transfer reactions of anionic C{sub 2}O{sub 4}{sup {minus}}, and cationic C{sub 2}O{sub 4}{sup +} species in supercritical carbon dioxide (scCO{sub 2}) over a range of reduced densities {rho}{sub r} = 0.36--1.5 and at a reduced temperature of T{sub r} = 1.03. The absorption spectrum measured in the visible region with a maximum around 700 nm is assigned to the dimer cation C{sub 2}O{sub 4}{sup +}. The pressure dependence of charge-transfer reactions was examined using dimethylaniline (DMA), benzoquinone (BQ), and oxygen as charge acceptors. The reaction rates of DMA with cations, and BQ with anions are at or near the diffusion-controlled limit. The rates decrease an order of magnitude with increase of pressure. The reaction of C{sub 2}O{sub 4}{sup +} with oxygen is much slower with an almost constant rate over the pressure range examined. The measured rate ...

2000-01-27

210

Thermal stability of mixed-cation #alpha#-sialon ceramics

This study aims to investigate the difference in the interaction of antimicrobial peptides with two classes of zwitterionic peptides, phosphatidylethanolamines (PE) and phosphatidylcholines (PC). Further experiments were performed on model membranes prepared from specific bacterial lipids, lipopolysaccharides (LPS) isolated from Salmonella minnesota. The structure of the lipid-peptide aqueous dispersions was studied by small-and wide-angle X-ray diffraction during heating and cooling from 5 to 85 C. The lipids and peptides were mixed at lipid-to-peptide ratios 10-10000 (POPE and POPC) or 2-50 (LPS). All experiments were performed at synchrotron soft condensed matter beamline A2 in Hasylab at Desy in Hamburg, Germany. The phases were identified and the lattice parameters were calculated. Alamethicin and melittin interact in similar ways with the lipids. Pure POPC forms only lamellar phases. POPE forms lamellar phases at low temperatures that upon heating transform ...

211

Synthesis of magnetic particles via a cationic-anionic surfactant vesicle method

A series of #alpha#-sialon (#alpha#') compositions containing mixed stabilising cations were prepared, by introducing additional CaO to a basic Sm #alpha#-sialon compositions. The thermal stability of these Sm-Ca-containing #alpha#-sialon phases was investigated using XRD, SEM and EDXS techniques. It was found that the addition of calcium into the Sm #alpha#-sialon systems greatly improved the stability of the #alpha#-sialon phases. Calcium was found to be incorporated into the #alpha#-sialon structure, coexistent with the samarium, and partitioning of the calcium and samarium was observed between the #alpha#' phase and grain boundary phases. This indicates a technique which may be used to improve the thermal stability of the #alpha#' phase while maintaining good refractory phases at the sialon grain boundaries.

2003-01-02

212

Synthesis of magnetic particles via a cationic-anionic surfactant vesicle method

In this work, a mixed cationic--anionic [i.e. cetyltrimethylammonium bromide-sodium octyl sulphate] surfactant system was used to synthesize the magnetite particles. The loading content of iron ions (Fe{sup 3+} and Fe{sup 2+}) into the surfactant system was varied to study its effect on the formation of magnetite, magnetic and morphological properties of the magnetite particles encapsulated by the surfactant vesicles. It has been verified that the vesicle-encapsulated magnetite particles with sizes from 100 to 200 nm were formed, which were almost independent of the loading content of iron ions. However, the morphological structure of the magnetite particles was dependent on the loading content of iron ions and there existed an optimal loading content for a full packing of the surfactant vesicles with the magnetite particles.

2006-10-15

213

Study on prepartion of polyethylene ion-exchange capillary by radiation induced graft co-polymerization

In this work, a mixed cationic--anionic [i.e. cetyltrimethylammonium bromide-sodium octyl sulphate] surfactant system was used to synthesize the magnetite particles. The loading content of iron ions (Fe"3"+ and Fe"2"+) into the surfactant system was varied to study its effect on the formation of magnetite, magnetic and morphological properties of the magnetite particles encapsulated by the surfactant vesicles. It has been verified that the vesicle-encapsulated magnetite particles with sizes from 100 to 200 nm were formed, which were almost independent of the loading content of iron ions. However, the morphological structure of the magnetite particles was dependent on the loading content of iron ions and there existed an optimal loading content for a full packing of the surfactant vesicles with the magnetite particles.

2006-10-01

214

Structures and properties of functional metal iodates

The synthetic process of polyethylene cation exchange capillary via radiation grafting polystyrene by simultaneous irradiation with "6"0Co #gamma#-ray source and sulfonation with concentrated H_2SO_4 was studied. The effects of dose, dose rate, monomer concentration, solvents, temperature and crosslinking agents on the graft copolymerization of styrene with polyethylene capillary were illustrated. The relationship between the radiation grafting conditions and the properties of ion-exchange capillary were examined. A polyethylene cation exchange capillary with I.D. 0.8 mm, length 20 m, exchange capacity 0.7 Meq/g 60% capacity in 10 s (flow rate 20 ml/min) was prepared. No significant loss of copacity was found from this ion-exchange capillary after 200 adsorption/regeneration cycles.

215

British Library Electronic Table of Contents (United Kingdom)

Metal iodates with a lone-pair containing I(V) that is in an asymmetric coordination geometry can form a diversity of unusual structures and many of them are promising new second homonic generation (SHG) materials. They exhibit wide transparency wavelength regions, large SHG coefficients and high optical-damage thresholds as well as moderately high thermal stability. In this paper, the structures and properties of the metal iodates are reviewed. The combination of d0 transition-metal cations with the iodate groups afforded a large number of metal iodates, with cations covering alkali metal, alkaline earth and lanthanide elements. Many of them are noncentrosymmetric (NCS) and display excellent SHG properties due to the additive effects of polarizations from both types of the asymmetric unit...

2011-01-01

216

Separation of lead-203 from cyclotron-bombarded thallium targets by ion-exchange chromatography

Separation of lead-203 from cyclotron-bombarded thallium targets by ion-exchange chromatography

A simple method is presented for the separation of lead-203 from copper-backed thallium cyclotron targets. The procedure involves cation-exchange chromatography in hydrochloric acid and hydrochloric acid-acetone mixtures. Further purification involves anion-exchange chromatography in nitric acid-hydrobromic acid mixtures. A cation-exchange column containing 3.0 g of resin can handle as much as 15 g of thallium and 160 mg of copper. An anion-exchange column containing 3.0 g of resin can separate lead from up to 200 mg of thallium and 10 mg of copper. Separations are extremely sharp and less than 0.1 ..mu..g of thallium and less than 0.1 ..mu..g of copper remain in the lead-203 fraction.

1982-07-01

217

Retention of pesticides in soil columns modified in situ and ex situ with a cationic surfactant

A simple method is presented for the separation of lead-203 from copper-backed thallium cyclotron targets. The procedure involves cation-exchange chromatography in hydrochloric acid and hydrochloric acid-acetone mixtures. Further purification involves anion-exchange chromatography in nitric acid-hydrobromic acid mixtures. A cation-exchange column containing 3.0 g of resin can handle as much as 15 g of thallium and 160 mg of copper. An anion-exchange column containing 3.0 g of resin can separate lead from up to 200 mg of thallium and 10 mg of copper. Separations are extremely sharp and less than 0.1 #mu#g of thallium and less than 0.1 #mu#g of copper remain in the lead-203 fraction. (author).

218

British Library Electronic Table of Contents (United Kingdom)

A study of the effect of a clayey soil modified in situ and ex situ with the cationic surfactant octadecyltrimethylammonium bromide (ODTMA), on the retention of linuron, atrazine and metalaxyl was carried out. Leaching of these compounds was studied in columns of a natural clayey soil and the same clayey soil modified by direct injection of the surfactant in situ, and in columns of a natural sandy soil and the same sandy soil modified by intercalation of a barrier of the clayey soil saturated ex situ with the surfactant. Breakthrough curves indicated the total immobilization of linuron in modified soils and a decrease in the leaching kinetics of atrazine and metalaxyl compared to what was obtained in the natural soil. The results indicate the use of the clayey soil modified in situ or ex s...

2007-01-01

219

Recovery of transplutonium elements from aqueous and water-ethanol solutions of sulfuric acid and their separation from other actinides

Magnetic susceptibility and electrical properties of Ln/sub 2/3+x/TiO/sub 3+y/ (Ln = Ce, Nd) at 77-450/sup 0/K

The behavior of Am, Cm, Bk, Cf, Es, and other actinides, as well as Zr, on anion and cation exchangers in aqueous and water-ethanol solutions of sulfuric acid as a function of the various components of the solution has been investigated. It has been discovered that the presence of ethanol in sulfuric acid solutions causes an increase in the distribution coefficients both on cation exchangers and on anion exchangers. The possibility of the use of ion exchangers for the preconcentration and separation of transplutonium elements from U, Np, Pu, Zr, and other elements which form strong complexes with sulfate ions over a broad range of concentrations of sulfuric acid has been demonstrated.

1988-05-01

220

Hydrogen-atom attack on methyl viologen in aqueous solution studied by pulse radiolysis

The magnetic susceptibility and electrical resistivity in cerium and neodymium titanate bronzes in Ln/sub 2/3+x/TiO/sub 3+y/ of the perovskite structure were investigated in the temperature range 77-450/sup 0/K. The deviation of the 1/x = f(T) dependence from the Curie-Weiss law, found for a majority of the compositions, was interpreted from the crystal-field effect based on the state of the Ce/sup 3 +/ and Nd/sup 3 +/ cations. For a number of the phases, a transition from metallic conductivity at high temperatures to semiconducting conductivity was detected at temperatures below 200-250/sup 0/K, which agrees well with the conclusion about the temperature dependence of x, related to the subsystem of Ti/sup 3 +/ cations.

1987-01-01

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221

Heteropolyanion-based ionic hybrid solid: A green bulk-type catalyst for hydroxylation of benzene with hydrogen peroxide

Using hydrogen at high pressures of up to 150 bar as an OH scavenger in aqueous MV"2"+ solutions (pH 1) it is possible to differentiate between two kinds of transient formed simultaneously by H-atom attack on methyl viologen. One of them is assigned to an H adduct on the N atom, MV"+H"+, with absorption bands identical to those of the radical cation, MV"+. The MV"+H"+ species deprotonates forming the long-lived radical cation, MV"+. The second type of transient produced is attributed to an H-adduct on the ring carbon, MV"2"+H, decaying by second-order kinetics. The formation of MV"+ by electron transfer from the propan-2-ol radical has been reinvestigated (pH 0 to 7); its absorption spectrum does not change in this pH range. Rate constants and molar extinction coefficients are presented. (U.K.).

1984-01-01

222

British Library Electronic Table of Contents (United Kingdom)

A novel heteropolyanion-based ionic hybrid was prepared by combining the divalent ionic liquid (IL) cation of 1,1'-(butane-1,4-diyl)-bis(3-methylimidazolium) with the Keggin-structured V-containing heteropolyanion, and characterized by ^1H NMR, FT-IR, ESI-MS, XRD, SEM, TG, BET surface area, melting point, and elemental analysis. Its catalytic activity was evaluated in the hydroxylation of benzene with aqueous H2O2, including the testing of the influence of organic cations, catalytic reusability and optimization of reaction conditions. This hybrid is characterized to be semi-amorphous nanoparticles with a IL-like composition. The hybrid catalyst leads to the liquid-solid biphasic reaction system for hydroxylation of benzene with H2O2, presenting such advantages as high catalytic activity, c...

2011-01-01

223

Electrochromic effects of charge separation in bacterial photosynthesis: theoretical models

Behavior of Np(VII, VI, V) in Silicate Solutions

The primary charge separation in photosynthetic bacteria generates a dimeric bacteriochlorophyll (BChl) cation and a bacteriopheophytin (BPheo) anion which lie within close proximity of each other (approx. 10 A). The two radicals also lie within van der Waals contact on opposite sides of a lone BChl bridging molecule. Spectral changes in the red (Q/sub y/) band of the bridge BChls have been observed on picosecond time scales following excitation of the reaction center (RC) and have been variously attributed to the formation of a BChl anion, to a charge-transfer state, or to electrochromic effects. They present calculations here which suggest that electrochromic effects caused by the photogenerated cation and/or anion can rationalize the optical changes observed in the flash photolyses as well as in trapping experiments.

1987-07-22

224

A method for preventing cathodic deposition of molybdenum subchloride in LiCl-KCl molten salt

Spectrophotometric methods were used to investigate the properties of neptunium(VII), (VI), and (V) in silicate solution. The transition of cationic neptunium(VII) to anionic species in non-complexing environments proceeds in the range of ?? 5.5 to 7.5. In the presence of carbonate, this transition occurs at ?? 10.0 to 11.5 and in silicate solutions at ?? 10.5-12.0. These findings show that cationic neptunium(VII) forms complexes with both carbonate and silicate and that the silicate complex is stronger than that of the carbonate. The competition of complex formation reactions for neptunium(VI) with carbonate and silicate and on the known complex stability constant of NpO2(CO3)34- allowed the NpO2SiO3 complex stability constant, log ? = 16.5, to be estimated. Determination of the formation constant of Np(V) complexes with SiO32- was not possible using similar methods.

2004-11-30

225

The proton optical-model potential in the interior of the nucleus

Effects of ions of Group IA, IIA, IIIB, and VIIB elements on the cathodic deposition of a molybdenum were investigated in a KCl-LiCl (eutectic)-MoCl/sub 3/ molten salt at 773 K (500/degree/C). The results can be summarized as follows: The addition of potassium, rubidium, cesium, and barium cations and fluorine anions to the KCl-LiCl (eutectic)-MoCl/sub 3/ molten salt is effective in depressing the cathodic deposition of the molybdenum subchloride, which hinders the smooth, flat electrodeposition of molybdenum. The addition of lithium, sodium, magnesium, calcium, strontium, and aluminum cations and bromine and iodine anions promotes the undesirable cathodic deposition of the molybdenum subchloride.

1989-01-01

226

Study of proton therapy on malignant tumors. Effects in twenty-four hours after proton irradiation

It is shown that elastic scattering data for protons of 100-200 MeV are consistent with an absorptive potential that is stronger in the nuclear interior and of the slightly shorter range than is usually assumend, which is more in agreement with microscopically calcuated potentials. Consequences for certain (p,p') and (e,e'p) reactions are shown. (orig.).

227

Study of GaSb+Bi system by proton backscattering method

We irradiated proton beams on the ears of rabbits and the Harding-Passey mouse melanoma and observed their morphological change. We used 52 MeV proton beams from the INS-FM cyclotron. We adjusted the energy of the proton beams to be at the plateau part of the Bragg curve, at the half-way point of the Bragg peak, and at the Bragg peak. The amount of radiation was 5000rad in each case. The Harding-Passey mouse melanoma was transplanted into the subcutan of a three week old mouse. In this experiment, we used tumors, the diameter of which grew up to 1.5-2cm in 2-3 weeks after the transplantation. Using the jroscope, we observed both lightly and severely damaged cells. Using proton irradiation with the Bragg peak located at depth of 1mm in the rabbit's ears, we studied the change in the tissue. Irradiated epidermis fell off and was eroded because of radiation damage, but the rear surface of the ...

1983-01-01

228

Stereochemistry definition of small organic molecules in solution: [H-H] NOE + molecular mechanics; Okreslenie sterochemii malych czasteczek organicznych w roztworze: [H-H] NOE + mechanika molekularna

The thermal stability of diffusion barriers is explored on the basis of Bi films at different expedients of deriving of films. The examinations were conducted on the electrostatic accelerator at KNU of name Karazin V.N. under conditions of an isothermal bakeout directly under a proton beam of 1,85 MeV energy.

229

Radiations against tumors: a bit old-fashioned?; Rayonnements contre tumeurs: un rien demode?

Scheme of theoretical method of molecular configuration definition for small organic molecules in solution has been presented. The method bases on measurements of nuclear Overhauser effects for proton-proton interactions and molecular mechanics calculations. 3 refs, 1 fig.

1994-12-31

230

Quenching of the 2psub(1/2)-2psub(3/2) proton spin-orbit splitting in the Sr-Zr region

The proton therapy gives an irradiation adapted to the shape and the depth of tumors ( eyes, head and neck) with a millimetric, even sub millimetric precision for the ophthalmological tumors. It is equally an excellent tool for the pediatrics tumors. For numerous treatments in France the proton therapy is associated to the photons treatments (x radiation). however, others physical treatments could modulate the medical offer, such thermal therapy or treatments by ultrasonic waves. (N.C.)

2004-09-01

231

Quantum molecular dynamics and molecular interactions studied by NMR and INS[Nuclear magnetic resonance; Proton tunnelling; Hydrogen bond

The constancy in excitation energy of the lowest 2/sup +/ state in the Sr isotopes across the N=56 subshell closure is shown to result from a reduction in the 2psub(1/2)-2psub(3/2) proton spin-orbit splitting as the 2dsub(5/2) neutron orbital is filled.

1984-06-14

232

Proton optical-model potential in the interior of the nucleus

The wavefunction of a particle extends into the classically forbidden barrier region of the potential energy surface. The consequence of this partial delocalisation is the phenomenon of quantum tunnelling, an effect which enables a particle to penetrate a potential barrier of magnitude greater than the energy of the particle. The tunnelling probability is an exponential function of the particle mass. The effect is therefore an important contribution to the behaviour of light atoms, in particular the proton. The hydrogen bond has long been appreciated to be an essential component of many biological and chemical systems, and the proton transfer reaction in the hydrogen bond is fundamental to many of these processes. The proton behaviour in the hydrogen bonds of benzoic acid, acetylacetone and calix-4-arene has been studied. A variety of techniques, both experimental and computational, were adopted for the study of the three ...

2002-07-01

233

Proton beam therapy control system

It is shown that elastic scattering data for protons of 100-200 MeV are consistent with an absorptive potential that is stronger in the nuclear interior and of the slightly shorter range than is usually assumend, which is more in agreement with microscopically calcuated potentials. Consequences for certain (p,p') and (e,e'p) reactions are shown.

1987-11-12

234

Pourquoi les quarks restent invisibles

A tiered communications architecture for managing network traffic in a distributed system. Communication between client or control computers and a plurality of hardware devices is administered by agent and monitor devices whose activities are coordinated to reduce the number of open channels or sockets. The communications architecture also improves the transparency and scalability of the distributed system by reducing network mapping dependence. The architecture is desirably implemented in a proton beam therapy system to provide flexible security policies which improve patent safety and facilitate system maintenance and development.

2010-09-21

235

Peculiarities of Swift Proton Transmission through Tapered Glass Capillaries

At the beginning of the seventies, physicists discovered a new scale in the matter structure. Protons and neutrons, components of the atomic nucleus, seemed to be constituted by even more elementar particles: the quarks. But while they seemed to move freely inside the protons, it was impossible to isolate one of these quarks. The Nobel Prize for physics rewarded the explanation of this phenomenon (3 pages)

2005-01-01

236

Optimizing radiotherapy of orbital and paraorbital tumors: intensity-modulated X-ray beams vs. intensity-modulated proton beams

A study of the 150-300 keV proton beam transmission through glass (borosilicate) tapered capillaries with different diameters of the input and output of the capillary was performed. The focusing effect was observed. The areal density of the transmitted beam is enhanced by approximately 20 times. It was shown that changing a taper angle from 0.5 deg to 1.7 deg evidences the increase of the transmission coefficient more than by 300 times keeping the initial energy spectrum of ions. (author)

2011-07-01

237

Operation of the AGS polarized beam

Purpose: This study presents a dosimetric optimization effort aiming to compare intensity-modulated (IM) X-rays and IM protons in 4 different orbital and paraorbital tumors. These are most challenging targets for standard radiotherapy due to their close relationship with the eyes and related structures. Methods and Materials: A primary orbital lymphoma, an optic nerve meningioma, a sphenoidal ridge meningioma protruding into the orbit, and a pediatric parameningeal paraorbital rhabdomyosarcoma were selected for the purpose of this study. Planning target volumes (PTVs) and organs at risk (OAR) were defined in each patient CT data set for each tumor site. IM X-ray and IM proton three-dimensional treatment plans were implemented. The following total tumor doses were prescribed: 30 Gy for the orbital lymphoma, 54 Gy for both meningiomas, and 50.4 Gy for the rhabdomyosarcoma case. Dose-volume histograms (DVHs) were obtained for all targets and OAR ...

2000-07-01

238

On the model of the nuclear shock wave generation in pion-nuclear collisions

A polarized proton physics run took place during January, 1988, at the Brookhaven AGS. It is the purpose of this paper to review the tune-up period preceding that run. This was the third such run at the AGS; the others occurred in June of 1984 and February of 1986. Some comparisons will be drawn among these. A thorough review of the history and hardware associated with the acceleration of polarized protons at the AGS can be found in the proceedings of the last meeting of this group at Protvino and will not be repeated here. 2 refs., 6 figs., 1 tab.

1988-01-01

239

New nuclei near the proton drip line around Z=40

Peak at 60 deg in angular proton distribution in inelastic pion-carbon interactions is interpreted as generation of Cherenkov gluon radiation in flucton, passing into the shock wave with successive nucleus decay. Investigation of hadron-nuclear interactions with anomalous peak in angular proton distribution can be used as additional means for study both of flucton and mechanism of hadron-nuclear interactions. 5 refs.

240

New nuclei near the proton drip line around Z =40

A "9"2Mo beam with an energy of E/A=70 MeV has been used to produce new isotopes near the proton drip line. The Michigan State University National Superconducting Cyclotron Laboratory A1200 fragment separator was used to detect the new isotopes "7"8Y, "8"2Nb, "8"5Mo, "8"6Tc, and "8"9","9"0Ru.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

241

Monte Carlo calculation of "1"2"9I and "2"3"7Np transmutation with relativistic protons

A {sup 92}Mo beam with an energy of {ital E}/{ital A}=70 MeV has been used to produce new isotopes near the proton drip line. The Michigan State University National Superconducting Cyclotron Laboratory A1200 fragment separator was used to detect the new isotopes {sup 78}Y, {sup 82}Nb, {sup 85}Mo, {sup 86}Tc, and {sup 89,90}Ru.

1992-12-01

242

La falta de financiacion publica hipoteca el futuro del acelerador de protones valenciano. La Universidad de Valencia tiene avanzado el diseno de este dispositivo de alta tecnologia

Monte Carlo calculations performed to validate observed capture reaction rates of "1"2"9I and "2"3"7Np were in a reasonable agreement with experimental data obtained by the Joint Institute for Nuclear Research. The most significant discrepancy between the measurements and calculations (within a factor of 3) was observed for the NpO_2 sample and Pb target at 3.7 GeV proton energy

1999-09-01

243

CERN Multimedia

"La Universidad de Valencia tiene avanzado el diseno de un acelerador lineal de protones, cuya culminacion depende del compromiso del Consell en sufragar la plantilla que necesitaria el centro para estar operativo" (1 page).

2002-01-01

244

Is the Ksub(#beta#)/Ksub(#alpha#) X-ray intensity ratio dependent upon the energy of an inducing proton

Energy dependence of Ksub(#beta#)/Ksub(#alpha#) intensity ratio of Si0_2 from proton induced ionisation

Ksub(#beta#)/Ksub(#alpha#) X-ray intensity ratios have been measured for various elements between Z = 29 and Z = 79 for incident proton energies of 23.6, 32.1 and 43.6 MeV. The results yield no evidence for a variation in ratio with particle energy. (orig.).

1980-01-01

245

Elastic scattering of 1 GeV protons from nuclei as a test for flucton model

The Ksub(#beta#)/Ksub(#alpha# 12) x-ray intensity ratio of the Si K spectrum was measured for proton impact on Si0_2 in the energy range 300-800 keV. An energy dependence of the intensity ratio was found and an explanation is given in terms of multiple ionisation. (author).

1980-04-01

246

Elastic scattering of 1 GeV protons from nuclei as a test for flucton model

Cross sections for elastic scattering of 12 GeV protons from /sup 40/Ca nuclei have been calculated using the flucton model. The influence of the collective flucton nucleon correlations on the calculated cross sections is examined. The calculated cross sections are in significant disagreement with the experimental data. This may be considered as an argument against the flucton model.

1982-04-01

247

Differences of the deformation parameter #beta# for 2"+_1 states of even-even spherical nuclei from electromagnetic excitation and proton scattering

Cross sections for elastic scattering of 12 GeV protons from "4"0Ca nuclei have been calculated using the flucton model. The influence of the collective flucton nucleon correlations on the calculated cross sections is examined. The calculated cross sections are in significant disagreement with the experimental data. This may be considered as an argument against the flucton model. (orig.).

248

Di-boson production at the Tevatron

Differences of the deformation parameters for the 2"+_1 states of even-even spherical nuclei extracted from electromagnetic excitation #beta#sup(em)_2 and from proton scattering #beta#sup(pp')_2 are discussed. It is found that the ratio #beta#sup(pp')_2/#beta#sup(em)_2 is equal to about unity and that there is a small isotope dependence for several incomplete shell nuclei. (orig.).

249

Cumulative kaon production by 10 GeV protons

The authors present some precision measurements on electroweak physics performed at the Tevatron collider at Fermilab. Namely they report on the boson-pair production cross sections and on triple gauge boson couplings using proton anti-proton collisions collected by the CDF and D0 experiments at the center-of-mass energy of 1.96 TeV. The data correspond to an integrated luminosity of up to 324 pb{sup -1}.

2005-05-01

250

Calculation of cosmic ray antiproton-proton ratio

The K"+- and K"-meson cumulative production cross sections are measured at 119"0 in the laboratory system on nuclei Be, Al, Cu and Ta bombarded by 10 GeV protons. Spectra of the K"-mesons consisting of only sea quarks show universal features characteristic of the spectra of cumulative particles, which contain valence quarks. Evidence is obtained for the fact that the energy density in a flucton can exceed the mean nuclear density by an order of magnitude.

251

Antiproton production of propagating cosmic rays under distributed reacceleration

Independent calculations of the antiproton-to-proton ratio by Gaisser and Maurer and by Badhwar et al. have produced conflicting results which obscure the interpretation of recent measurements of cosmic ray antiprotons. A detailed reexamination of these calculations has been performed and these differences have been resolved. We find that the first calculation was essentially correct and the reported fluxes of antiprotons are significantly higher than expected for secondary antiprotons in conventional models of cosmic ray propagation, as indicated by other recent calculations.

1982-01-15

252

Proton magnetic resonance spectroscopy reflects cellular proliferative activity in astrocytomas

The available measurements on the cosmic-ray antiproton/proton ratio show an excess of antiprotons above predictions derived in the framework of the standard picture of cosmic-ray origin and propagation. Calculations are performed of the production from collisions of cosmic rays with the interstellar gas under the condition of distributed reacceleration. It could be shown that the calculated antiproton/proton ratio is enhanced compared to that derived from the leaky box model, but it remains difficult to bring it into agreement with the data by reasonable astrophysical assumptions. 15 references.

1987-09-01

253

High performance protonic ceramic membrane fuel cells (PCMFCs) with Sm_0_._5Sr_0_._5CoO_3_-_#delta# perovskite cathode

We examined whether proton magnetic resonance spectroscopy (MRS) could provide accurate information on histological grade and cell proliferation in astrocytomas. We studied 23 patients with astrocytomas: five grade II, 10 grade III and eight with grade IV (glioblastoma multiforme). We performed proton MRS and determined the Ki-67 labeling index (LI), a tumour proliferation marker, in the same areas of the astrocytomas, and examined the statistical relationship between proton MRS and Ki-67 LI. The N-acetylaspartate (NAA)/creatine-phosphocreatine (Cr) and NAA/choline (Cho)-containing compound ratios were always significantly lower and the Cho/Cr ratios significantly higher than those for normal brain. The Cho/Cr ratio correlated positively and the NAA/Cho ratio inversely with Ki-67 LI. These findings suggest that the Cho signal in proton MRS reflects cellular proliferation. In Kaplan-Meier survival ...

2000-05-01

254

Thermographic studies of the interaction between hydrolyzed polyacrylonitrile and Ca/sup 2 +/, Fe/sup 3 +/, Cu/sup 2 +/ ions

Protonic ceramic membrane fuel cells (PCMFCs) based on proton-conducting electrolytes have attracted much attention because of many advantages, such as low activation energy and high energy efficiency. A stable, easily sintered perovskite oxide BaCe_0_._5Zr_0_._3Y_0_._1_6Zn_0_._0_4O_3_-_#delta# (BCZYZ) as electrolyte for proton-conducting solid oxide fuel cells (SOFCs) with Sm_0_._5Sr_0_._5CoO_3_-_#delta# (SSC) composite cathode is investigated. By fabricating thin membrane BCZYZ electrolyte (#approx#20 #mu#m) synthesized by a modified Pechini method on NiO-BCZYZ anode support, PCMFCs are assembled and tested by selecting SSC perovskite cathode with high mixed ionic and electronic conductivities. An open-circuit potential of 1.015 V, a maximal power density of 528 mW cm"-"2, and a low polarization resistance of the electrodes of 0.15 #OMEGA# cm"2 is achieved at 700 "oC. The results indicate that BCZYZ ...

2010-04-02

255

The separation and determination of trace elements in iron ore

Reasons were revealed for the fresh water resistance of sediments of hydrolyzed polyacrylonitrile obtained from interaction of it with Fe/sup 3 +/, Ca/sup 2 +/ and Cu/sup 2 +/ cations which are in the saline solutions of these metals.

1982-01-01

256

The relation between net calcium, alkali cation and chloride movements in red cells exposed to salicylate.

The separation, concentration, and determination of trace elements in iron ores are described. After the sample has been dissolved, the iron is separated by liquid-liquid extraction with a liquid cation-exchanger, di-(2-ethylhexyl) phosphoric acid. The trace elements aluminium, cadmium, calcium, chromium, cobalt, copper, lead, magnesium, manganese, mercury, potassium, sodium, vanadium, and zinc are determined in the aqueous phase by atomic-absorption spectrophotometry.

2008-05-01

257

THE RECYCLING OF MIXTURES OF HEAVY METALS FROM WASTE USING ELECTRO- DEPOSITION

1. From a 150 mM-NH4 salicylate medium salicylate enters human red cells with a rate constant of 1.9 min-1 at 0 degrees C. 2. Salicylate increases the red cell permeability for Ca2+ (and Mg2+). There...Full Text Available

1979-02-01

258

Environmental Research Database

ObjectivesObjectives Not AvailableDescriptionWe will study the electrodeposition of metals from solutions containing a~%~ mixture of metal cations, in order to discover the conditions which lead to the separation of the metals. Measurements will be made both using small glass cells and using a more realistic size (10 cm x 10 cm electrodes) of electrodeposition cell.~%~

1996-01-31

259

Synthesis, Characterization and Biological Properties of Anions of Bivalent Transition Metal [Co(II) and Ni(II)] Complexes With Acylhydrazine Derived ONO Donor Schiff Bases

Synergetic extraction in systems with dicarbollide and bidentate phosphonate

Some acylhydrazine derived ONO donor Schiff bases and their Co(II) and Ni(II) complexes have been prepared having the same metal ion (cation) but different anions. These synthesized metal(II)...Full Text Available

2000-01-01

260

Structure properties and magnetic susceptibility of diluted magnetic semiconductor Y_2_-_xHo_xO_3

A process for the extraction of tervalent metal cations from 3 M HNO[sub 3] highly radioactive waste based on synergetic mixtures of dicarbollide with neutral organophosphonate (dibutyl diethylcarbamoylmethylene phosphonate) is proposed. Due to the great hydrophobicity of dicarbollide anion, the species ML[sub n[sup 3+

1994-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

261

Stability ranges of Li-#alpha#'-sialons

The polycrystalline samples of Y_2_-_xHo_xO_3 (0.10#<=#x#<=#1.80) were synthesized by ceramic technology. The X-ray powder diffraction data were collected and the crystal structures were refined by the Rietveld method for the samples Y_2_-_xHo_xO_3 (x=0.00, 0.20, 0.40, 1.20, 1.80, 2.00). Holmium ions Ho"3"+ were randomly distributed over two cationic sites 8b and 24d in the space group Ia3 in all refined structures. Cation-anion-cation bonds important for superexchange interaction were determined. Magnetic susceptibility measurements were done by the Faraday method in the temperature range 290 to 620 K and a behaviour in accordance with the Curie-Weiss law was obtained. The molar Curie's constants linearly depend on concentration. The effective magnetic moments of Ho"3"+ ions were smaller than the free ion value. The Curie-Weiss paramagnetic temperatures indicated antiferromagnetic interaction. The gram ion susceptibilities confirmed the ...

1995-01-01

262

Reactions of carbon acids and 1,3-dipoles in the presence of ionic liquids

The formation of #alpha#'-sialon using Li as a modifying cation was investigated. The effects of the Li content, firing temperatures and Si/Al ratios on #alpha#'- yield were studied. The results indicated that at lower sintering temperatures the stabilisation of #alpha#'-sialons was obtained but the high weight losses of Li at higher temperatures limited the stabilisation. Increased ''Al'' content in the compositions resulted in an increase in the stability of Li-#alpha#'-sialon at higher temperatures, by the formation of a liquid phase which retains Li in the system. (orig.).

1993-10-04

263

Phosphorus-containing catalyst and catalytic cracking process utilizing the same

The review is devoted to the use of ionic liquids as solvents, immobilized organocatalysts and reagents in reactions involving carbon acids and 1,3-dipoles, which are widely used to prepare practically valuable organic compounds of various classes. The characteristic features of processes in the presence of ionic liquids, the effects of the structure of cations and anions on the regio-, stereo- and enantioselectivities of reactions and methods of recovery of ionic liquids are considered.

2010-09-14

264

Phosphorus-containing catalyst and catalytic cracking process utilizing the same

A phosphorus-containing low alkali metal content zeolitic catalyst made from a clay starting material is provided. The catalyst is obtained by contacting a partially cation exchanged calcined zeolite-containing catalyst with a dihydrogen phosphate anion or a dihydrogen phosphite anion. A hydrocarbon catalytic cracking process utilizing the phosphorus-containing catalyst is also provided.

1985-02-12

265

Oil well drilling clay conditioners and method of their preparation

A phosphorus-containing low alkali metal content zeolitic catalyst made from a clay starting material is provided. The catalyst is obtained by contacting a partially cation exchanged calcined zeolite-containing catalyst with an anion such as a dihydrogen phosphate anion or a dihydrogen phosphite anion and additionally with an ammonium salt other than a salt of an inorganic acid of phosphorus. A hydrocarbon catalytic cracking process utilizing the phosphorus-containing catalyst is also provided.

1985-03-12

266

Ion-exchange scheme for selective removal of gadolinium nitrate from the moderator system of 540 MWe Indian PHWRs using macroporous strong acid cation and macro porous weak base anion resins

Drilling fluid additives are prepared by oxidation of sulfonated lignin-containing materials with manganese dioxide under highly acidic conditions to make manganese lignosulfonates. Additional improvements in the rheological properties of the additives may be obtained by complexing the manganese lignosulfonate so obtained with a heavy metal cation (preferably iron or copper), by, for example, addition of ferrous sulfate or ferric sulfate to the manganese lignosulfonate. These products show the requisite combination of rheological properties for a satisfactory drilling fluid additive or conditioner.

1984-05-08

267

Discovery and investigation of properties of new inorganic and organic compounds of astatine

Gadolinium nitrate has been employed in Indian nuclear reactors for the first time as soluble neutron poison in the heavy water moderators of the 540 MWe PHWRs TAPS 3 and 4, as a fast acting secondary shut down system (SDS-2); and also for reactivity shim. For this purpose, the moderator purification system is currently equipped with special ion-exchange columns/schemes, developed by present authors. However, for gadolinium removal from moderator in the post SDS-2 scenario, the two stage ion-exchange - cation bed operation followed by mixed bed operation - results in low pH conditions persisting in the moderator for a few hours, which gives rise to certain operational problems. The present paper describes a mixed bed ion-exchange scheme employing macro-porous strong acid cation and macro-porous weak base anion resins, which has been developed to eliminate acidic conditions and gives a better pH control. The cation to anion ...

2008-12-01

268

Cyclopeptide alkaloids. Synthesis of the ring system and its ion affinity

Short review of works on astatine chemistry carried out by authors for the last thirty years are done. Discovery of single-charged cation stable in aqueous solutions is predominant attainment of authors in the branch of inorganic chemistry. The first successful synthesis of heptavalent astatine compounds is a new and significant result of the last years. New direction in the chemistry of the fifth halogen is organic chemistry of astatine

269

Characterization of DTPA complexes and conjugated antibodies of astatine

Several examples of the 14-membered, para-bridged ring system of the cyclopeptide alkaloids have been synthesized via an active ester cyclization. The yield of monomeric cyclopeptide varied from 1 to 33% and was affected by the amino acid substitution pattern and amide conformation of the linear peptide precursors. Both the synthetic models and a naturally occurring cyclopeptide alkaloid, ceanothine B, bind monovalent (Li"+) and divalent (Ca"2"+, Mg"2"+) cations. 4 figures, 1 table.

270

Catalytic hydrocarbon reactions over supported metal oxides. Progress report, April 1, 1994--January 31, 1995

The complex formation of astatine(I) cation with diethylene triamine pentaacetic acid (DTPA) and characterization of the complexes were investigated by electromigration in free electrolytes and by gel-chromatography on Sephadex G 25. The conjugation procedure for the production of At-DTPA conjugated polyclonal antibodies is described. (author) 15 refs.; 2 figs.

271

CONCENTRATION OF PLUTONIUM BY CATION EXCHANGE--STABILIZATION OF Pu(III) IN NITRIC ACID

Oxide catalysis plays a central role in hydrocarbon processing and improvements in catalytic activity or selectivity are of great technological importance because these improvements will translate directly into more efficient utilization of hydrocarbon supplies and lower energy consumption in separation processes. An understanding of the relationships between surface structure and catalytic properties is needed to describe and improve oxide catalysts. Our approach has been to prepare supported oxides that have a specific structure and oxidation state and then employ these structures in reaction studies. Our current research program is focused on studying the fundamental relationships between structure and reactivity for two important reactions that are present in many oxide-catalyzed processes, partial oxidation and carbon-carbon bond formation. Oxide catalysis can be a complex process with both metal cation and oxygen anions participating in the chemical ...

1995-01-31

272

Synthesis, crystal structures and spectroscopic properties of RbBaTaS{sub 4} and K{sub 2}BaTa{sub 2}S{sub 11}

A study to define the effectiveness limits of sulfamic acid and to discover other better stabilizers for Pu(III) is described. Ascorbic and isoascorbic acids, used in conjunction with sulfamic acid reduced Pu(IV) to stable Pu(III) in nitric acid. Aminoguanidine sulfate also retarded the oxidation of Pu(III) but did not reduce Pu(IV). (J.R.D.)

1959-02-01

273

Determination of distal dose edge location by measuring right-angled prompt-gamma rays from a 38 MeV proton beam

Single crystals of RbBaTaS{sub 4} (1) and K{sub 2}BaTa{sub 2}S{sub 11} (2) were obtained from the reactions of Ta, with in situ formed fluxes of A{sub 2}S{sub 3} (A = K, Rb), BaS, and S at 500 C. Compound 1 crystallizes in the orthorhombic space group Pnma with a = 9.3286(5), b = 7.0391(4), c = 12.4365(7) A, V = 816.6(1) A{sup 3}, Z = 4. Compound 2 crystallizes in the monoclinic space group P2{sub 1}/c with a = 14.5280(10), b = 12.6347(7), c = 17.5148(12) A, {beta} = 94.744(8) , V = 3203.9(4) A{sup 3}, Z = 4. The structure of RbBaTaS{sub 4} (1) consists of isolated tetrahedral [TaS{sub 4}]{sup 3-} anions and Rb{sup +} and Ba{sup 2+} cations. The Ba{sup 2+} cations are surrounded by nine sulfur atoms forming distorted tricapped trigonal prisms, whereas the Rb{sup +} cations are in an irregular environment of ten sulfur atoms. The structure of K{sub 2}BaTa{sub 2}S{sub 11} (2) consists of two different dinuclear [Ta{sub ...

2010-10-15

274

Beta-delayed proton emission: a new series of precursors, and the measurement of 10"-"1"6 s nuclear lifetimes

In clinical applications, it is very important to accurately determine the range of a proton beam in a patient. Recently, a prototype prompt-gamma scanning system, called a prompt-gamma scanner (PGS), has been constructed at Hanyang University in Korea with the collaboration of the Korean national cancer center (NCC), based on a series of Monte Carlo simulations. The PGS system is composed of a prompt-gamma collimator, a CsI(Tl) scintillation detector, a multi-channel analyzer (MCA), a precision movement system, and an integrated readout system. The prompt-gamma collimator is designed to effectively shield high-energy neutrons from the proton beam passage and subsequent capture gammas. The PGS system can be used to scan the distribution of the prompt gammas in the patient from the proton beam passage. The distribution of the prompt gammas can then be used to determine the proton beam range or the distal ...

2007-09-21

275

Acid-base behavior of the ground and excited states of platinum(II) complexes of quinoxaline-2,3-dithiolate

The results of investigation into a new series of Z-even nuclei - precursors of delayed protons (PDP) -"6"5Ge, "8"9Se, "9"3Kr, "8"1Zr, and "8"5Mo are presented. PDP were obtained by irradiation of targets in the following reactions: Zn(He, 2n) "6"5Ge, 22 MeV; "4"0Ca("3"2S, 2 pn) "1"9Se, 100 MeV; "6"0Ni ("1"60, 3 n), "7"3Kr, 75 MeV; "5"2Cr ("3"2S, 3n)"8"1Zr, 110 MeV; "5"6Fe("3"2S, 3n)"8"5Mo, 120 MeV. The targets (self-sustaining foils of thickness approximately 1.2 mg/cm"2) were placed at an angle of 15 deg to the direction of the ion beam. Upon irradiation targets were moved downwards into a measuring position. The spectra of protons, X and gamma-rays, and also the spectra of p - x, p-#gamma#, x - #gamma# coincidences accompanying the decay of "6"5Ge, "6"9Se,"7"3Kr and "8"1Zr, and "8"5Mo were measured. The measured half-lives are equal, to 31.5+-1.9, 27.3+-0.5, 28.5+-1.1, 6.3+-0.5, and 5.6 +-0.9 s respectively. The experimental spectra are ...

276

Zero-motion correlations in high-energy proton elastic scattering on sup 40 Ca with noneikonal nucleon-nucleon amplitude

The acid-base behavior of the ground and excited states of Pt(qdt){sub 2}{sup 2{minus}} and Pt(phen)(qdt), where qdt=quinoxaline-2,3-dithiolate and phen = 1,10-phenanthroline, has been studied. The pH-dependent changes in the charge-transfer absorption and emission spectra for both complexes are attributed to protonation of the quinoxalinedithiolate ligand at the imine nitrogen. For Pt(qdt){sub 2}{sup 2{minus}}, single protonation leads to a large red shift (2582 cm{sup {minus}1}) of the low-energy charge-transfer-to-dithiolate absorption band and the emergence of a new red-shifted emission feature at 728 nm. In solutions of pH below 6, a second protonation takes place at the other qdt ligand, yielding Pt-(Hqdt){sub 2}. This neutral complex has been isolated and characterized by {sup 1}H NMR spectroscopy and elemental analyses. The ground-state basicity constants of the two protonation steps have been ...

1995-06-21

277

Zero-motion correlations in high-energy proton elastic scattering on "4"0Ca with noneikonal nucleon-nucleon amplitude

Using a noneikonal expression for the two-body scattering amplitude, consistent with the proton-nucleon scattering data, the cross-section of the 1.04 GeV-proton elastic scattering on {sup 40}Ca is calculated by the Glauber-Sitenko theoretical scheme in the framework of the coherent density fluctuation model (CDFM) as well as of the independent-particle model (IPM). It is shown that the use of the noneikonal amplitude in the CDFM calculations improves the agreement with the experimental data especially at larger scattering angles in contrast to the case of the independent-particle model. To that end a decisive role play the zero-motion flucton correlations taken into account in the CDFM. (orig.).

1990-07-01

278

Two dimensional NMR and NMR relaxation studies of coal structure

Using a noneikonal expression for the two-body scattering amplitude, consistent with the proton-nucleon scattering data, the cross-section of the 1.04 GeV-proton elastic scattering on "4"0Ca is calculated by the Glauber-Sitenko theoretical scheme in the framework of the coherent density fluctuation model (CDFM) as well as of the independent-particle model (IPM). It is shown that the use of the noneikonal amplitude in the CDFM calculations improves the agreement with the experimental data especially at larger scattering angles in contrast to the case of the independent-particle model. To that end a decisive role play the zero-motion flucton correlations taken into account in the CDFM. (orig.).

279

Transverse Imaging of the Proton in Exclusive Diffractive pp Scattering

This report covers the progress made on the title project for the project period. Four major areas of inquiry are being pursued. Advanced solid state NMR methods are being developed to assay the distribution of the various important functional groups that determine the reactivity of coals. Special attention is being paid to methods that are compatible with the very high magic angle sample spinning rates needed for operation at the high magnetic field strengths available today. Polarization inversion methods utilizing the difference in heat capacities of small groups of spins are particularly promising. Methods combining proton-proton spin diffusion with [sup 13]C CPMAS readout are being developed to determine the connectivity of functional groups in coals in a high sensitivity relay type of experiment. Additional work is aimed at delineating the role of methyl group rotation in the proton NMR relaxation behavior of coals.

1992-11-25

280

Proton scattering by short lived sulfur isotopes

In a forthcoming paper we describe a new approach to rapidity gap survival (RGS) in the production of high-mass systems (H = dijet, Higgs, etc.) in exclusive double-gap diffractive pp scattering, pp -> p + H + p. It is based on the idea that hard and soft interactions are approximately independent (QCD factorization), and allows us to calculate the RGS probability in a model-independent way in terms of the gluon generalized parton distributions (GPDs) in the colliding protons and the pp elastic scattering amplitude. Here we focus on the transverse momentum dependence of the cross section. By measuring the ''diffraction pattern'', one can perform detailed tests of the interplay of hard and soft interactions, and even extract information about the gluon GPD in the proton from the data.

2006-04-20

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281

New Measurements of the Proton Electromagnetic Form Factor Ratio at Low Q{sup 2}

Elastic and inelastic proton scattering has been measured in inverse kinematics on the unstable nucleus {sup 40}S. A phenomenological DWBA analysis yields a quadrupole deformation parameter {beta}{sub 2} = 0.35 {+-} 0.05 for the 2{sup +}{sub 1} state. Consistent phenomenological and microscopic proton scattering analyses have been applied to all even-even Sulfur isotopes from A = 32 to A = 40. The microscopic analysis used microscopic collective model densities and a modified Jeukenne-Lejeune-Mahaux effective interaction. This analysis suggests the presence of a neutron skin in the heavy sulfur isotopes. The analysis is consistent with normalization values for {lambda}{sub {upsilon}} and {lambda}{sub {omega}} of 0.95 for both the real and imaginary parts of the JLM potential. (author)

1999-07-01

282

Neutron capture cross sections for unstable nuclei in the mass 90 region derived from proton capture measurements. [Strength functions

Polarization measurements are allowing the electric to magnetic form factor ratio of the proton to be determined with unprecedented precision. Recent results indicate that there is a large deviation from unity in the proton form factor ratio around Q{sup 2}{approx_equal}0.35 GeV{sup 2}. Furthermore, the deviation from unity is attributed to a deviation of the electric form factor from standard fits and calculations. A new, partially completed, experiment will significantly improve the existing data and will determine the presence, if any, of a narrow structure in the form factor ratio. The new measurement, combined with the expected high precision cross section measurements, will allow the extraction of individual form factors with unprecedented accuracy at low Q{sup 2}.

2009-08-15

283

Investigation of neutron and proton distributions of He, Li, and Be isotopes using the new Skyrme-Force parameters

Experimental measurements were made of the production cross sections and energy distributions of gamma rays emitted when the stable targets /sup 88/Sr, /sup 89/Y and /sup 90/Zr are exposed to protons in the energy range 3 to 8 MeV. The data are being analyzed using a recent version of the Uhl statistical model code. One conclusion is that while the gamma-ray strength functions employed reproduce the proton capture cross sections, they do not achieve the same degree of hardness observed in the measured spectra. To do so, their lower energy regions must be modified; such changes, however, do not affect the capture cross sections. 7 references.

1978-09-01

284

Fast PIN-diode beam loss monitors at Tevatron

The proton and neutron densities, root-mean-square (rms) radii of proton density and neutron density, and neutron skin thickness of "4"-"1"0He, "6"-"1"1Li, and "7"-"1"2Be isotopes are calculated using Skyrme-Hartree-Fock method with SLy4, SLy5, SLy6, and SLy7 force parameters. The evaluated results are compared with experimental data. Also, the results of halo nuclei ("6","8He, "1"1Li, and "1"1Be) are compared with the results of other isotopes for selected nuclei having the same neutron configuration.

2010-01-01

285

Electrolytic membrane formation of fluoroalkyl polymer using a UV-radiation-based grafting technique and sulfonation

The article is devoted to results of fine time structure of particle losses in Tevatron with use of fast beam loss monitors (BLM) based on PIN-diodes. An ultimate goal of the new BLMs is to distinguish losses of protons and antiprotons from neighbor bunches with 132 ns bunch spacing in the Tevatron collider upgrade. The devices studied fit well to the goal as they can recognize even seven times closer - 18.9 ns - spaced bunches` losses in the Tevatron fixed target operation regime. We have measured main characteristics of the BLM as well as studied the proton losses over 10 decades of time scale - from dozen of minutes to dozen of nanoseconds. Power spectral density of the losses is compared with spectra of the proton beam motion.

1997-07-01

286

Electrode materials: a challenge for the exploitation of protonic solid oxide fuel cells

A sulfonated fluoroalkyl graft polymer (FGP) membrane was prepared as a polymer electrolyte. First, the FGP membrane was grafted with styrene under UV irradiation. The grafted FGP was then sulfonated to functionalize it for proton conductivity. The grafting degree of the membrane increased with increasing grafting time during UV irradiation. The proton conductivity of the membrane increased with increasing grafting degree. The swelling ratio was independent of the grafting time, however, the water uptake increased with increasing grafting degree. Based on these results, it was found that the UV-initiated styrene grafting occurred along the membrane thickness direction. Moreover, the membrane was embedded within the glass fibers of the composite. This composite electrolytic membrane had 1.15 times the proton conductivity of a Nafion 117 membrane.

2011-03-01

287

Effect of Two-Boson Exchange on Parity-Violating e-p Scattering

High temperature proton conductor (HTPC) oxides are attracting extensive attention as electrolyte materials alternative to oxygen-ion conductors for use in solid oxide fuel cells (SOFCs) operating at intermediate temperatures (400-700 "0C). The need to lower the operating temperature is dictated by cost reduction for SOFC pervasive use. The major stake for the deployment of this technology is the availability of electrodes able to limit polarization losses at the reduced operation temperature. This review aims to comprehensively describe the state-of-the-art anode and cathode materials that have so far been tested with HTPC oxide electrolytes, offering guidelines and possible strategies to speed up the development of protonic SOFCs. (topical review)

2010-08-01

288

Beam Profile Measurement and its Application to Calculate Beam Emittance Using Wire Scanner for the PEFP 20MeV linac

We compute the corrections from two-photon and {gamma}-Z exchange in parity-violating elastic electron-proton scattering, used to extract the strange form factors of the proton. We use a hadronic formalism that successfully reconciled the earlier discrepancy in the proton's electron to magnetic form factor ratio, suitably extended to the weak sector. Implementing realistic electroweak form factors, we find effects of the order 2%-3% at Q{sup 2} < or approx. 0.1 GeV{sup 2}, which are largest at backward angles and have a strong Q{sup 2} dependence at low Q{sup 2}. Two-boson contributions to the weak axial current are found to be enhanced at low Q{sup 2} and for forward angles. We provide corrections at kinematics relevant for recent and upcoming parity-violating experiments.

2008-02-29

289

Vibrational spectroscopy of bacteriorhodopsin mutants: light-driven proton transport involves protonation changes of aspartic acid residues 85, 96, and 212

A 20-MeV proton accelerator is developed by Proton Engineering Frontier Project (PEFP) at Korea Atomic Energy Research Institute (KAERI). The 20MeV accelerator consists of 50keV proton injector, 3MeV RFQ (Radio frequency Quadrupole), 20MeV DTL (Drift Tube Linac) and 20MeV beam line. The beam profile was measured at the end of the 20MeV beam line with wire scanner. Moreover the beam emittance was calculated from the quad scan method using beam line quadrupole magnets. In this paper, the beam profile measurement results are presented and the emittance measurement from the quad scan method is discussed

2010-10-01

290

Transition density of quasiparticle-phonon model in semimicroscopic analysis of 25 MeV proton and 104 MeV #alpha#-particle scattering on "9"0Zr nucleus

Fourier transform infrared (FTIR) difference spectra have been obtained for the bR----K, bR----L, and bR----M photoreactions in bacteriorhodopsin mutants in which Asp residues 85, 96, 115, and 212 have been replaced by Asn and by Glu. Difference peaks that had previously been attributed to Asp COOH groups on the basis of isotopic labeling were absent or shifted in these mutants. In general, each COOH peak was affected strongly by mutation at only one of the four residues. Thus, it was possible to assign each peak tentatively to a particular Asp. From these assignments, a model for the proton-pumping mechanism of bR is derived, which features proton transfers among Asp-85, -96, and -212, the chromophore Schiff base, and other ionizable groups within the protein. The model can explain the observed COOH peaks in the FTIR difference spectra of bR photointermediates and could also account for other recent results on site-directed mutants of bR.

1988-11-15

291

Traditional Fusion reaction: D + T n (14.07 MeV) + 4He (3.52 MeV ...

Russian 1987. p. 452. USSR Dao Tien Kkhoa Knyaz'kov, OM Kukhtina,

1987-04-14

292

The opening of the two pores of the Hv1 voltage-gated proton channel is tuned by cooperativity

as for direct energy conversion in specialized direct electrical energy conversion plants. Figure 1. An energetic (~163KeV) proton and a 11boron nucleus fuse ...

293

The Antibacterial Activity of Human Neutrophils and Eosinophils Requires Proton Channels but Not BK Channels

SUMMARYIn voltage-gated sodium, potassium, and calcium channels the functions of ion conduction and voltage sensing are performed by two distinct structural units: the pore domain...Full Text Available

2010-01-01

294

Simultaneous activation of NADPH oxidase-related proton and electron currents in human neutrophils

Electrophysiological events are of central importance during the phagocyte respiratory burst, because NADPH oxidase is electrogenic and voltage sensitive. We investigated the recent suggestion that...Full Text Available

2006-06-01

295

Protons and glucose metabolism in shock

Generation of reactive oxygen species by the NADPH oxidase complex is an important bactericidal weapon of phagocytes. Phorbol myristate acetate (PMA) is a potent agonist for this “respiratory...Full Text Available

2000-06-06

296

Proton storage ring (PSR) diagnostics and control system

When oxygen is limiting, animals can ferment glucose via several metabolic pathways varying in energetic efficiency and leading to various end products (such as lactate, succinate, or propionate). Because the pH dependence of H/sup +/ production by fermentation is opposite to that by hydrolysis of adenosine triphosphate formed in the fermentation, the total number of moles of protons generated is always two per mole of fermentable substrate. However, two and three times more adenosine triphosphate can be turned over per mole of protons produced in succinate and propionate fermentations, respectively, than in lactate fermentation. At its limit, this advantage would achieve the same balance between H/sup +/ production and H/sup +/ consumption during ATP cycling that is observed in aerobic metabolism, a situation observed in certain alcohol fermentations. Since proton balance during anaerobiosis is clearly adaptable, we ...

1983-01-01

297

Proton spin lattice relaxation studies in lithium ammonium sulfate LiNH_4SO_4

When any new accelerator or storage ring is built that advances the state of the art, the diagnostic system becomes extremely important in tuning the facility to full specification. This paper will discuss the various diagnostic devices planned or under construction for the PSR and their connection into the control system.

1983-01-01

298

Proton G{sub E}/G{sub M} from beam-target asymmetry

Lithium ammonium sulfate (LAS) undergoes a phase transition at Tsub(c1) = 459.5deg K from a paraelectric phase (phase 1) to a ferroelectric phase (phase II) and again at Tsub(c2) = 283deg K to a polar ferroelastic phase (phase III). Proton spin lattice relaxation investigations in the temperature range 480-77deg K at 10 MHz show discontinuous changes in Tsub(1) at the transition temperatures, indicating first order phase transitions. The absence of the slow motion region (#omega#sub(not)tausub(not)>>1) shows that the ammonium ions are reorienting fast enough to keep the resonance absorption line narrow down to liquid nitrogen temperatures. The possibility of a second minimum and a low activation energy, Esub(a) = 2.659 kcal/mole, in phase III suggest the possibility of tunnelling of the protons at low temperatures. The nature of the transitions have been discussed in the light of the available literature. The unusually high activation ...

1978-12-31

299

Preparation of new proton exchange membrane based on self-assembly of poly(styrene-co-styrene sulfonic acid)-b-poly(methyl methacrylate)/poly(vinylidene fluoride) blend

The ratio of the proton's electric to magnetic form factor, G{sub E}/G{sub M}, can be extracted in elastic electron-proton scattering by measuring cross sections, beam-target asymmetry, or recoil polarization. Separate determinations of G{sub E}/G{sub M} by cross sections and recoil polarization observables disagree for Q{sup 2}>1 (GeV/c){sup 2}. Measurement by a third technique might uncover an unknown systematic error in either of the previous measurements. The beam-target asymmetry has been measured for elastic electron-proton scattering at Q{sup 2} = 1.51 (GeV/c){sup 2} for target spin orientation aligned perpendicular to the beam momentum direction. This is the largest Q{sup 2} at which G{sub E}/G{sub M} has been determined by a beam-target asymmetry experiment. The result, {mu}G{sub E}/G{sub M}=0.884{+-}0.027{+-}0.029, is compared to previous world data.

2006-09-15

300

Phytochrome-controlled Hydrogen Ion Excretion by Avena Coleoptiles ¹

Amphiphilic block copolymers are synthesized by sulfonation of poly(styrene-b-methyl methacrylate) (PS-b-PMMA) using acetyl sulfate, and are blended with poly(vinylidene fluoride) (PVDF) to prepare a new proton exchange membrane, in which PMMA is miscible with PVDF. The morphology and the transport properties of the membranes are investigated as functions of the degree of sulfonation as well as the blend ratio. Notable transition of phase-separated morphology is observed as the PVDF content of the blend is increased. Both the proton conductivity and the ion-exchange capacity (IEC) of the membrane increase with increasing the degree of sulfonation of PS-b-PMMA, and they are also enhanced as the phase-separated domains of blend membrane are well-ordered. Unlike the Nafion membrane, the proton conductivity of the blend membrane increases up to 90 C, indicating the blend membrane shows better thermal stability than the Nafion ...

2009-03-01

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301

PIXE-PIGE analysis of some Indian medicinal plants

A red light-induced, far red reversible stimulation of proton efflux from apical segments of etiolated Avena sativa L. cv. Victory coleoptiles was observed. The acidification...Full Text Available

1977-04-01

302

Oxidation of phosphine by iron(III) chloride complexes supported on activated charcoal

The quantitative estimation of various trace element concentrations in medicinal plants is necessary for determining their effectiveness in treating various diseases and for understanding their pharmacological action. Elemental concentrations of some selected medicinal plants of north east India was measured by proton induced X-ray emission (PIXE) and proton induced {gamma}-ray emission (PIGE) techniques. PIXE measurements were carried out using 2.4 MeV collimated protons from the 3 MV tandetron accelerator of NCCCM, Hyderabad (India) while the PIGE measurements were carried out using 3 MeV protons from the same accelerator in the same laboratory. Accuracy and precision of the techniques were assured by analyzing certified reference materials in the same experimental conditions. Various elements of biological importance in man's metabolism were found to be present in varying concentrations in ...

2010-06-15

303

On the probability of flucton production in the 1p-shell nuclei

It has been discovered that iron(III) chloride complexes supported on activated charcoal oxidize phosphine under normal conditions. The process accelerates as the concentration of the chloride ions and the proton acid increases.

1988-06-01

304

On the performances of Intensity Modulated Protons, RapidArc and Helical Tomotherapy for selected paediatric cases

Probabilities of flucton production have been calculated for the 1p-shell nuclei and its modification by the Yastrov method. The results obtained are in a qualitative agreement with the data resulting from the analysis of experiment in an assumption of a flucton mechanism of proton-nuclear inclusive reactions with the production of cumulative particles.

305

ORNL RSIC-18 - NASA Technical Report Server (NTRS)

BackgroundTo evaluate the performance of three different advanced treatment techniques on a group of complex paediatric cancer cases.MethodsCT...Full Text Available

306

Nucleon resonance studies in phenomenological analysis of the CLAS

W. Wayne Scott. ABSTRClCT. Primary proton and secondary particle doses (both .... W. Wayne Scott and R. G. Alsmiller, Jr., Comparisons of Results Ob- ...

307

Near Infrared-Fluorescent and Magnetic Resonance Imaging Molecular Probe with High T1 Relaxivity for In Vivo Multimodal Imaging

First comprehensive data on the evolution of nucleon resonance photocouplings with photon virtuality Q{sup 2} are presented for excited proton states in the mass range from 1.4 to 2.0 GeV.

2006-07-01

308

Measuring the quark contribution to the proton spin through. nu. p yields. nu. p

A new gadolinium chelating NIR fluorescent molecular probe increases T₁ relaxivity of water protons, facilitating combined optical and magnetic resonance imaging.

2010-06-07

309

Measurement of the parity violating asymmetry A{sub {gamma}} in n{yields}+p{yields}d+{gamma}

The LSND (Liquid Scintillator Neutrino Detector) experiment will be performed at LAMPF in the next several years. The main goal of the experiment is to search for {nu}{sub {mu}}-{nu}{sub e} oscillations with high sensitivity; however, an increasingly important by-product of this search is to measure {nu}p {yields} {nu}p elastic scattering and determine the strange quark contribution, {Delta}s, to the spin of the proton. With the 800-MeV proton energy of LAMPF, neutrinos are produced from pion decay-in-flight with an average energy of about 150 MeV. This energy is sufficiently high so that the {nu}p {yields} {nu}p cross section is large and is sufficiently low so that the low Q{sup 2} approximation (Q{sup 2} {much lt} m{sub p}{sup 2}) is valid and the cross section can be expressed in a simple form dependent upon {Delta}s as the only unknown. LAMPF with its 1-mA proton intensity is, therefore, an ideal accelerator to perform ...

1991-01-01

310

Malolactic fermentation: electrogenic malate uptake and malate/lactate antiport generate metabolic energy.

The weak interaction between neutrons and protons has never been resolved experimentally. In analogy with the strong NN interaction, the weak NN interaction at low energy can be parametrized in terms of a meson exchange model with parity violating meson-nucleon couplings. Unlike the measured proton-proton weak interaction, the neutron-proton weak interaction is sensitive to the weak pion-nucleon coupling constant H{sub {pi}}{sup 1}. This coupling, which is responsible for the longest-ranged part of the weak NN interaction and is therefore an essential part of any description of weak interactions in nuclei, remains undetermined despite many years of effort. A measurement of the gamma ray directional asymmetry A{sub {gamma}} in the capture of polarized neutrons by parahydrogen has been proposed at Los Alamos National Laboratory. The goal of this experiment is to determine A{sub {gamma}} with a relative standard uncertainty of ...

2000-02-11

311

Kinetics of the Vacuolar H⁺-Pyrophosphatase ¹

The mechanism of metabolic energy production by malolactic fermentation in Lactococcus lactis has been investigated. In the presence of L-malate, a proton motive force composed of a membrane potential...Full Text Available

1991-10-01

312

Generation of a proton motive force by histidine decarboxylation and electrogenic histidine/histamine antiport in Lactobacillus buchneri.

The responses of the vacuolar membrane (tonoplast) proton-pumping inorganic pyrophosphatase (H⁺-PPase) from oat (Avena sativa L.) roots to changes in Mg²⁺ and...Full Text Available

1992-12-01

313

Enrichment of Thermophilic Propionate-Oxidizing Bacteria in Syntrophy with Methanobacterium thermoautotrophicum or Methanobacterium thermoformicicum

Lactobacillus buchneri ST2A vigorously decarboxylates histidine to the biogenic amine histamine, which is excreted into the medium. Cells grown in the presence of histidine generate both a transmembrane...Full Text Available

1993-05-01

314

Electronic structure and proton spin-lattice relaxation in PdH

Thermophilic propionate-oxidizing, proton-reducing bacteria were enriched from the granular methanogenic sludge of a bench-scale upflow anaerobic sludge bed reactor operated at 55°C with a mixture...Full Text Available

1992-01-01

315

Effects of Protons and HZE Particles on Glutamate Transport in Astrocytes, Neurons and Mixed Cultures

We report a detailed augmented-plane-wave energy-band study and wave-function analysis of stoichiometric PdH which shows that, even though the Fermi surface of PdH is qualitatively similar to that of silver, the simple ''proton model'' is not valid. Instead, the screening of the proton in PdH is found to be larger than in an isolated H atom due, in part, to the formation of a H-Pd bonding band below the bottom of the d-band complex. This result, which is in qualitative agreement with Switendick's earlier calculation, is confirmed by ultraviolet photoemission experiments. A partial density-of-states (DOS) analysis in the energy range spanned by the six valence and conduction bands reveals the quantitative details of the bonding mechanism between the Pd and H constituents. At the Fermi energy, the high Pd d to H s DOS ratio approx. 10.3 is found to be far higher than expected in silver, despite the fact that the Fermi-surface geometry is similar. ...

316

Early forecast of radiation-hazardous solar cosmic ray fluxes on the neutron monitors data

... ions. MATERIALS AND METHODS Cell Culture Culture of NT2/D1 cells was carried out as described previously (18, 19). NT2 cells were plated at a density of 2. ... ...

317

Dimeric subunit stoichiometry of the human voltage-dependent proton channel Hv1

The system of the early forecast of radiation hazardous fluxes of solar cosmic rays in space on the basis of the real time neutron monitors data obtained by the NMDB (Neutron Monitor Data Base) network is created. The forecast system is based on a short cut technique of definition of a spectrum of solar protons from the data of the limited number of neutron monitor stations and with a simplified procedure of accounts. It is shown that the results of computations of solar proton spectra with the short-cut technique little differ from spectra obtained with a complete technique at energies less than 5 GeV. Thus the good agreement between derived from the neutron monitor data intensities of solar protons in an energy range of hundreds MeV with the data of direct measurements of solar protons at GOES-11 spacecraft is observed. The maximum of increase on neutron monitors outstrips on several hours (2-10) an ...

2010-01-01

318

Differences between neutron and proton density rms radii of "2"0"4 "2"0"6 "2"0"8Pb determined by 104 MeV #alpha#-particle scattering

In voltage-gated Na⁺, K⁺, and Ca²⁺ channels, four voltage-sensor domains operate on a central pore domain in response to membrane voltage. In contrast, the voltage-gated...Full Text Available

2008-06-03

319

Correlations between the proton temperature anisotropy and Alfv\\'en-cyclotron waves in the solar wind

Differential cross sections of elastic scattering of 104 MeV #alpha# particles from "2"0"4,"2"0"6,"2"0"8Pb have been measured with high angular accuracy. The analyses are based on a folding model treating the proton and neutron distributions independently. The proton distributions were taken from precise electron scattering results. The neutron distributions were parametrized by a modified Gaussian the parametrers of which were varied in order to fit the experimental cross sections. The resulting rms radii of the neutron distributions exceed the rms radii of the proton distributions by #DELTA#r=0.22 +- 0.09 fm for "2"0"4Pb, #DELTA#r = 0.19 +- 0.09 fm for "2"0"6Pb, and #DELTA#r = 0.30 +- 0.07 fm for "2"0"8Pb.

320

Compact Dielectric Wall Accelerator Development For Intensity Modulated Proton Therapy And Homeland Security Applications

Correlations are studied between the power density of Alfv\\'en-cyclotron waves (having frequencies between 0.02 and 2 Hz) and the ratio of the perpendicular and parallel temperature of the protons. The wave power spectrum is evaluated from high-resolution 3D magnetic field vector components, and the ion temperatures are derived from the velocity distribution functions as measured in fast solar wind during the Helios-2 primary mission at radial distances from the Sun between 0.3 AU and 0.9 AU. From our statistical analysis, we obtain a striking correlation between the increases in the proton temperature ratio and enhancements in the wave power spectrum. Near the Sun the transverse part of the wave power is often found to be by more than an order of magnitude higher than its longitudinal counterpart. Also the measured ion temperature anisotropy appears to be limited by the theoretical threshold value for the ion-cyclotron instability. This ...

2010-01-01

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321

Charge compensation for NADPH oxidase activity in microglia in rat brain slices does not involve a proton current

Compact dielectric wall (DWA) accelerator technology is being developed at the Lawrence Livermore National Laboratory. The DWA accelerator uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. Its high electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The DWA concept can be applied to accelerate charge particle beams with any charge to mass ratio and energy. Based on the DWA system, a novel compact proton therapy accelerator is being developed. This proton therapy system will produce individual pulses that can be varied in intensity, energy and spot width. The system will be capable of being sited in a conventional linac vault and provide intensity modulated rotational therapy. The status of the developmental new technologies that make the compact system possible will be reviewed. ...

2009-06-17

322

Cadmium biosorption rate in protonated Sargassum biomass

The membrane properties of isolated cultured microglia have been extensively studied but it is important to understand their properties in situ, where they protect the brain against...Full Text Available

2008-09-01

323

COSPIN-ANISOTROPY TELESCOPE for ULY - PDS - NASA

Biosorption of the heavy metal ion Cd{sup 2+} by protonated nonliving brown alga Sargassum fluitans biomass was accompanied by the release of hydrogen protons from the biomass. The uptake of cadmium and the release of proton matched each other throughout the biosorption process. The end-point titration methodology was used to maintain the constant pH 4.0 for developing the dynamic sorption rate. The sorption isotherm could be well represented by the Langmuir sorption model. A mass transfer model assuming the intraparticle diffusion in a one-dimensional thin plate as a controlling step was developed to describe the overall biosorption rate of cadmium ions in flat seaweed biomass particles. The overall biosorption mathematical model equations were solved numerically yielding the effective diffusion coefficient D{sub e} about 3.5 {times} 10{sup {minus}6} cm{sup 2}/s. This value matches that obtained for the desorption process ...

1999-03-01

324

Assessment of structural changes of human teeth by low-field nuclear magnetic resonance (NMR)

To calibrate channels A1 to A4 for particles with Z >= 1, tests were done on the IBIS accelerator at AERE, Harwell, which gave protons up to 3 MeV. ...

325

Zero-motion flucton correlations in high-energy proton elastic scattering on /sup 40/C

A technique of low-field pulsed proton nuclear magnetic resonance (NMR) spin relaxation is described for assessment of age-related structural changes (dentin and pulp) of human teeth in...Full Text Available

2010-01-01

326

Zero-motion flucton correlations in high-energy proton elastic scattering on "4"0C

The 1.04 GeV-proton elastic scattering from /sup 40/Ca is studied in the framework of the coherent density fluctuation model (CDFM). The calculations are carried out in the Glauber theoretical scheme with three different charge densities. It is shown that: i) the account of the flucton correlations leads to results considerably different from those obtained in the independent particle Glauber approach (IPGA); ii) in contrast to the case of IPGA the use of a more realistic density improves the agreement of CDPM-results with the experimental data.

1985-03-01

327

Two-photon exchange at low Q{sup 2}

The 1.04 GeV-proton elastic scattering from "4"0Ca is studied in the framework of the coherent density fluctuation model (CDFM). The calculations are carried out in the Glauber theoretical scheme with three different charge densities. It is shown that: i) the account of the flucton correlations leads to results considerably different from those obtained in the independent particle Glauber approach (IPGA); ii) in contrast to the case of IPGA the use of a more realistic density improves the agreement of CDPM-results with the experimental data. (orig.).

328

The joint project for high-intensity proton accelerators

We studied two-photon exchange for elastic electron-proton scattering at low Q{sup 2}. Compact approximate formulas for the amplitudes were obtained. Numerical calculations were done for Q{sup 2}{<=}0.1 GeV{sup 2} with several realistic form factor parametrizations, yielding similar results. They indicate that the corrections to the magnetic form factor can visibly affect the cross-section and proton radii. For low-Q{sup 2} electron-neutron scattering two-photon exchange corrections were shown to be negligibly small00.

2007-03-15

329

The Proton structure function F(2) in the resonance region

Japan Atomic Energy Research Institute (JAERI) and the High Energy Accelerator Research Organization (KEK) are promoting the joint project integrating both the Neutron Science Project (NSP) of JAERI and the Japan Hadron Facility Project (JHF) of KEK for comprehensive studies on basic science and technology using high-intensity proton accelerator. This document describes the joint project prepared by the Joint Project Team of JAERI and KEK to construct accelerators and research facilities necessary both for the NSP and the JHF at the site of JAERI Tokai Establishment. It was originally written in English and translated into Japanese with some corrections. (author)

2000-02-01

330

The 0.9 MW proton beam at PSI and studies on a 10 MW cyclotron

Unique measurement of the proton structure function F2 in a wide two-dimensional region of x and Q**2 has been reported. The accessible kinematics covers entire resonance region up to W=2.5 GeV in the Q**2 interval from 0.1 to 4.5 GeV**2. Obtained data allowed for the first time an evaluation of moments of the structure function F2 directly from experimental data as well as an intensive study of the Bloom-Gilman duality phenomenon.

2003-06-01

331

Surface doping of conjugated polymers by graphene oxide and its application for organic electronic devices

The conceptual design for a cyclotron that could possibly deliver a 10 MW proton beam, presented at the previous ADTT conference, is discussed in comparison with the operational experience gained with 0.9 MW beam power in the upgraded cyclotron facility at PSI that has reached the design goal of 1.5 mA at 590 MeV in 1995. Some critical aspects of the design are e.g. RF power and beam loading, beam loss and activation, space charge effects and bunching. 12 refs., 2 figs., 1 tab.

1997-09-01

332

Sol-gel approaches for solid electrolytes and electrode materials. Technical report

Surface doping of conjugated polymers is realized by depositing a thin layer of graphene oxide (GO) on top of the polymers. The high proton density and the unique 2D structure of GO facilitate the protonic surface doping of conjugated polymers to achieve high conductivities. This finding represents a new strategy for improving charge transport across the metal/conjugated polymer interface to achieve much improved performance in organic solar cells. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

2011-04-26

333

Simple method for high-temperature separation of thallium isotopes from a bulk lead target

Sol-gel chemistry has a great many potential applications in the preparation of unique electrochemical materials, from non-equilibrium transition metal oxides which may be of use as high energy density electrodes, to high-surface area mixed oxides which may possess high proton conductivity, to novel composite structures consisting of inorganic gels in combination with organic, electronic, and ionic conductors. This paper reviews prior work on proton conduction in gel systems and presents recent work regarding electrode materials prepared by sol-gel methods and inorganic-organic materials.

1995-07-14

334

Simple method for high-temperature separation of thallium isotopes from a bulk lead target

A method is proposed for the quantitative isolation of radiothallium in gas form from proton-bombarded lead of mass up to 20 g. The molten lead is kept at about 800 K in hydrofluoric-acid vapor (HF/H/sub 2/O approx. = 1) at a reduced pressure (less than or equal to4 Pa). We used 99.9% lead with the U-240 cyclotron at the Nuclear Research Institute, Academy of Sciences of the Ukrainian SSR, or the phasotron at the Join Nuclear Research Institute, which gave protons at 65 and 680 MeV correspondingly.

1988-03-01

335

Provenance study of excavated pottery from Beirut using PIXE cluster analysis

A method is proposed for the quantitative isolation of radiothallium in gas form from proton-bombarded lead of mass up to 20 g. The molten lead is kept at about 800 K in hydrofluoric-acid vapor (HF/H_2O #approx =# 1) at a reduced pressure (#<=#4 Pa). We used 99.9% lead with the U-240 cyclotron at the Nuclear Research Institute, Academy of Sciences of the Ukrainian SSR, or the phasotron at the Join Nuclear Research Institute, which gave protons at 65 and 680 MeV correspondingly.

336

Proton and deuteron spin structure function measurements in the resonance region

The study of imported ceramics found in Beirut and suspected to belong to north Syrian products will provide key evidence for the roles in trade of the various postulated centers in northern Syria and northern Lebanon. It is proposed that a comprehensive range of likely north Syrian products imported to Beirut will be chemically analyzed by PIXE (proton induced X-ray emission) in order to characterize, compare and isolate the various regional production centers that supplied the city from the Persian to Byzantine periods. In this work, we were mainly focusing on the characterization of Amrit products, by using 3 MeV proton beam and Al funny filter, as X-ray absorber.

2006-08-01

337

Primakoff effect in {eta} -photoproduction off protons

The RSS collaboration has measured the spin structure functions of the proton and the deuteron at Jefferson Lab using the Hall C HMS spectrometer, a polarized electron beam and a polarized solid target. The asymmetries A and A were measured in the region of the nucleon resonances (0.82 GeV < W < 1.98 GeV) at an average four momentum transfer of Q2 = 1.3 GeV2. The extracted spin structure functions and their kinematic dependence will make a significant contribution in the study of higher-twist effects and polarized duality tests. A description of the experiment and the latest findings of the analysis will be presented.

2003-07-01

338

Physics with Polarized Antiprotons

We analyse data on forward {eta} -meson photoproduction off a proton target and extract the {eta}{yields}{gamma}{gamma} decay width utilizing the Primakoff effect. The hadronic amplitude that enters into our analysis is strongly constrained because it is fixed from a global fit to available {gamma}p{yields}p{eta} data for differential cross-sections and polarizations. We compare our results with present information on the two-photon {eta} -decay from the literature. We provide predictions for future PrimEx experiments at Jefferson Laboratory in order to motivate further studies. (orig.)

2010-05-15

339

Nucleon momentum distributions of 39(K), 40(Ca) and 48(Ca)

Polarized antiprotons produced by spin filtering with an internal polarized gas target provide access to a wealth of single- and double-spin observables, thereby opening a window to physics uniquely accessible with the HESR at FAIR. This includes a first measurement of the transversity distribution of the valence quarks in the proton, and a first measurement of the moduli and the relative phase of the time-like electric and magnetic form factors G{sub E,M} of the proton. In polarized and unpolarized pp-bar elastic scattering open questions like the contribution from the odd charge-symmetry Landshoff-mechanism at large |t| and spin-effects in the extraction of the forward scattering amplitude at low |t| can be addressed.

2006-04-15

340

New diffractional approach to proton-nucleus scattering

The proton momentum distributions of (39)K,(40)Ca and (48)Ca are calculated from the model-independent charge distributions obtained from analyses of electron elastic scattering and muonic atoms, and also from the charge distributions calculated from the single-particle potential method in the framework of the flucton model. The sensitivities of the momentum distribution to different regions of the charge distribution are determined. The analysis is extended to the neutron distributions using the single-particle potential method, and the differences between the proton and neutron momentum distributions are examined. The resulting momentum distribution in the case of (40)Ca is used for analyzing the quasielastic electron scattering.

1983-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

341

Neutron flux spectra in the FFTF In-Reactor Thimble

A ''coherent flucton'' nuclear model is proposed which provides for new possibilities for particle scattering studies on nuclei. It is based on the data of nuclear matter density distribution and is used for calculating the ground state energy of Fermi system terminals. The ''coherent flucton'' model is applied to the distribution of 1 GeV protons on "2"8Si, "3"2S, "4"0Ca, "4"8Ca, "5"8Ni, "2"0"8Pb nuclei. The calculations by the model agree well with experimental data.

2002-11-01

342

Measurement of the inclusive Z production cross section with the CMS detector

Neutron spectra measured in the FFTF In-Reactor Thimble (IRT) by proton recoil proportional counters, proton recoil emulsions, and passive dosimeters have been evaluated and compared with each other and with three-dimensionl diffusion theory calculated spectra for the purpose of validating the passive dosimeter spectrum adjustment technique. The least squares data adjustment code, FERRET, was used to combine measured reaction rates, calculated spectra, and dosimeter cross sections, resulting in adjusted spectra and cross sections with uncertainties and correlations that properly account for uncertainties and correlations on the input parameters.

1982-12-01

343

Low temperature proton irradiation of amorphous Pd/sub 80/Si/sub 20/ prepared by ion implantation

First measurements of inclusive Z production cross sections in muon and electron decay channels at 7 TeV are presented for proton-proton collisions in the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC). The comparison of the kinematic quantities as well as the studies of selection efficiencies demonstrate a good agreement between simulated events and current data. The measured inclusive cross section for Z($\\gamma^{*}$) production agrees with NNLO QCD cross section calculations and current parton distribution functions.

2010-01-01

344

L-subshell and total M-shell X-ray production cross sections of Ta, W, Pt, Au, Pb and Bi by 0.7-2.4 MeV protons

The damage induced by low-temperature proton irradiation in amorphous Pd/sub 80/Si/sub 20/ prepared by ion implantation is studied via electrical resistivity measurements. Our experimental results concerning the initial damage rate and the resistivity saturation are compared to the results obtained for electron and high energy /sup 16/O irradiation of amorphous Pd/sub 80/Si/sub 20/ quenched from the melt. The resistivity curve is analyzed in terms of irradiation-induced point defects.

1984-05-01

345

Ionization and fragmentation of DNA, RNA bases induced by proton impact

The L-subshell and total M-shell X-ray production cross sections of Ta, W, Pt, Au, Pb and Bi have been measured by protons of energy between 0.7 and 2.4 MeV. The obtained results for X-ray production cross sections have been compared with the existing experimental data, prediction of the ECPSSR theory and also with fitted empirical cross sections of Strivay and Weber.

2006-06-01

346

Exploring the structure of the proton through polarization observables in l p \\to jet X

We present recent results obtained in the Toulouse's group that deal with proton to base and nucleoside interactions. We stress the weakness of the sugar part in the nucleoside, i.e. the uridine molecule under scrutiny. Since some parts of the fragmentation spectrum correspond to the fragmentation of a 'pure' uracil molecule, i.e. the RNA base, an 'additivity rule' seems to prevail for the nucleoside, something that still has to be confirmed. Moreover, some results that deal with the secondary electronic emission from uracil are also displayed.

2008-02-01

347

Effects of relativity and wave functions on atomic L- and M-shell ionization by protons

We present results for a complete set of polarization observables for jet production in lepton proton collision, where the final state lepton is not observed. The calculations are carried out in collinear factorization at the level of Born diagrams. For all the observables we also provide numerical estimates for typical kinematics of a potential future Electron Ion Collider. On the basis of this numerical study, the prospects for the transverse single target spin asymmetry are particularly promising. This observable is given by a certain quark-gluon correlation function, which has a direct relation to the transverse momentum dependent Sivers parton distribution.

2011-01-01

348

Chiral solitons in nuclei: Electromagnetic form factors

Atomic L- and M-shell ionization cross sections by protons have been calculated in the plane-wave Born approximation for /sub 79/Au and /sub 92/U with incident energy from 0.1 to 3 MeV with use of relativistic and nonrelativistic Hartree-Slater wave functions. These results are compared with those from the screened hydrogenic model to study the effects of relativity and wave functions. The relativistic and wave-function effects are found to operate in opposite directions. For M/sub 1,2,3/-subshell cross sections, severe cancellations occur between these two factors.

1984-10-01

349

Basic Science Beamline(TR104) at PEFP

We calculate the electromagnetic form factors of a bound proton. The chiral quark-soliton model provides the quark and antiquark substructure of the proton, which is embedded in nuclear matter. This procedure yields significant modifications of the form factors in the nuclear environment. The sea quarks are almost completely unaffected, and serve to mitigate the valence quark effect. In particular, the ratio of the isoscalar electric to the isovector magnetic form factor decreases by 20% at Q{sup 2}=1 GeV{sup 2} at nuclear density, and we do not see a strong enhancement of the magnetic moment.

2004-12-01

350

Application of the digital waveform analysis to Bragg curve spectrometer

PEFP(Proton Engineering Frontier Project) is developing beamlines for various application fields by using the high current 100MeV proton linear accelerator. Beamlines were characterized and categorized by the beam energy, average currents, and irradiation conditions. Among these beamlines the TR104 is designed for the basic science and the research of the aerospace. Before the construction and installation of beamlines, we try to practice and prepare the detail process of installation by the precedent study of TR104 beamline in KAERI site. By this work installation process was checked and confirmed for the same condition of the PEFP site

2010-10-01

351

Analysis of the chemical transformations induced at the surface of polyacrylonitrile and polymethacrylonitrile films by 5 keV proton beams

Energy and angular double-differential cross-section (DDX) data of fragment production reactions by neutrons or protons are very scarce due to experimental difficulties of fragment detection. We adopted a Bragg curve spectrometer (BCS), which is a gridded-ionization chamber that can identify fragments on the basis of the Bragg peak value. We have been developing the BCS for neutron and proton-induced reactions applying the digital waveform analysis technique to obtain better ability of particle discrimination than the analog electronic circuit. (T. Tanaka)

2004-11-01

352

A thermal hydraulic investigation on ADSR liquid lead target

In this work, the chemical transformations induced by 5 keV protons (10{sup 6} ion cm{sup -2}) at the surface of 0.4 {mu}m polyacrylonitrile and polymethacrylonitrile films are analysed by XPS and IRRAS. Spectroscopic changes in both the polymers are globally similar, the most significant feature being a lower relative concentration of nitrogen with respect to carbon closer to the surface. Quantitatively, this change is more marked in the case of polyacrylonitrile which suggests a direct relation with the hydrogen in {alpha} to the nitrile function.

1999-05-02

353

A new calculation of the cosmic-ray antiproton spectrum in the Galaxy and heliospheric modulation effects on this spectrum using a drift plus wavy current sheet model

Computational fluid dynamics(CFD) code FLUENT was used to simulate the thermal hydraulic processes occurring in conceptual design of the accelerator-driven subcritical reactor(ADSR) liquid lead target. The purpose of the analysis is to investigate the thermal hydraulic characteristics of liquid lead as ADSR target material with various target geometries and injection locations of proton beam. In the calculation analysis, the local temperature of the liquid lead target rises to the boiling temperature very rapidly. When the proton beam is injected from the bottom of the target system, the duration time to reach the boiling temperature is longer and the temperature distribution is flatter than other cases.

1998-05-01

354

A dependence of cumulative pion production cross sections in proton-nuclear interactions at high energies

The expected interstellar antiproton spectrum arising from cosmic-ray interactions in the Galaxy is recalculated, and the modulation of both antiprotons and protons is calculated using a two-dimensional modulation model incorporating gradient and curvature drifts and a wavy current sheet as well as the usual diffusion, convection, and energy-loss effects. Significant differences in the antiproton/proton ratio for different solar magnetic field polarities are predicted as well as a 'low-energy' component for antiprotons below about 1 GeV. 28 refs.

1989-09-01

355

Expression of Na(+)-H+ exchange and ATP-dependent proton extrusion in growing rat IMCD cells

The A dependence of cumulative pion production yield cross sections on the basis of the comparison of the data on relative pion yields on Be,C,Al,Ti,Mo and W nuclei at the 159 deg angle laboratory system for the incident proton energy E_0 from 25 to 62 GeV is considered. The regular A dependence on cumulative variable X is noted. The results are compared with the data at E_0< 10 GeV. A possible interpretation of the observed behaviour on the basis of the hypothesis of the flucton mechanism of the pion production in the cumulative region is discussed. 15 refs.; 4 figs.

356

Ultratrace determination in high-purity molybdenum and tungsten with ion chromatographic trace-matrix-separation. Pt. 1; Selection and optimization of the separation step. Ultraspurenanalytik in hochreinem Molybdaen und Wolfram mit ionenchromatographischer Spuren-Matrix-Trennung. Tl. 1; Auswahl und Optimierung des Trennschritts

As the last step of urinary acidification, the inner medullary collecting duct (IMCD) is thought to secrete protons into the tubular lumens by means of a H(+)-translocating adenosinetriphosphatase (H(+)-ATPase). However, recent studies have also shown the existence of Na(+)-H+ exchange activity in IMCD cells. Although the physiological function of the antiporter in IMCD cells is unknown, activation of Na(+)-H+ exchange in other cell-culture systems has been suggested to be closely associated with the process of cell growth. Thus presence of Na(+)-H+ exchange may relate to the growth phase of these cells. To examine intracellular pH (pHi) regulation in growing IMCD cells, we studied proton transport by Na(+)-dependent and Na(+)-independent mechanisms by microfluorimetry using the pHi-sensitive dye 2',7'-bis(carboxyethyl)-5,6-carboxyfluorescein acetoxymethyl ester (BCECF/AM). Actively growing cells, defined by (3H)thymidine ...

1990-03-01

357

Theoretical study on the effects of oxygen doping on the lithium ion conductive perovskite-type manganese fluoride of KxBa(1-x)/2MnF3

Known trace-matrix-separation and enrichment procedures for the refractory metals Mo and W use very time-consuming batch-techniques. This paper presents the application of a quasicontinuous liquid chromatographic (LC) technique as a step towards automated ultratrace separation. The anionic peroxo complexes from Mo(VI) and W(VI) are used for the trace-matrix-separation. Optimization of the peroxide concentration permits a complete removal of all cationic analyte traces on the HPLC-suitable cation exchanger Nucleosil SA. The high chromato-graphic efficiency also allows a direct ion chromatographic separation of the removed traces. This leads to conclusions about the contribution of the analyte traces on the trace-matrix-separation column and the limits of determination. (author). 13 refs.; 12 figs.; 5 tabs.

1991-11-20

358

British Library Electronic Table of Contents (United Kingdom)

Previously, we demonstrated that the lithium ion conduction in the perovskite-type manganese fluoride is attributed to counter cation-site vacancy mechanism. The divalent counter cation-doped KxBa(1-x)/2MnF3 was theoretically predicted as the lithium ion conductor in the perovskite-type manganese fluoride. In this study, we considered the oxygen doping for KxBa(1-x)/2MnF3 to realize the higher lithium ion conductivity. It is because lithium ion forms the stronger ionic bond with the doped oxygen anion. The hybrid-DFT calculations were performed to investigate the lithium ion conduction in the oxygen-doped KxBa(1-x)/2MnF3. The calculation results were discussed from the viewpoints of the potential energy curve, electron densities, and charge and spin densities. The effect of the lithium ion...

2009-01-01

359

Strontium-90 and cesium-137 in service water from June to December, 1981

Silica Polyamine Composites: New Supramolecular Materials for Cation and Anion Recovery and Remediation

Service water, 100 l each, was collected at an intake of a water treatment plant and at a tap after water was left running for five minutes. The carriers of strontium and cesium were added to water immediately after sampling, and the sample was vigorously stirred and filtered. Then it was passed through a cation exchange column at a rate of 80 ml/min. Strontium and cesium were eluted with hydrochloric acid from the cation exchange column, and separated. After the radiochemical separation, the mounted precipitates were counted for activity using low background beta counters normally for 60 min. Net sample counting rates were corrected for counter efficiency, recovery, self absorption and decay to obtain the content of strontium-90 and cesium-137 radioactivity per sample aliquot. From the results, concentrations of these nuclides in the original sample were calculated. The maximum values obtained were 0.29 pCi/l of Sr-90 in Kyoto in August, 1981, ...

1981-12-01

360

Removal of Cr(III) from aqueous solutions using zeolite NaY prepared from rice husk ash

The surface coverage of amorphous silica gels used in the synthesis of silica polyamine composites has been investigated by 29Si NMR. By diluting the polyamine anchor silane, chloropropyl trichlorosilane, with methyl trichlorosilane it was found that surface coverage could be markedly improved for a range of amine polymers after grafting to the silica surface. The commensurate decrease in the number of anchor points and increase in the number of free amines results in an increase in metal capacity and/or an improvement in capture kinetics. Solid state CPMAS-13C NMR has been employed to investigate the structure and metal ion binding of a series of these composite materials. It is reported that the highly branched polymer, poly(ethyleneimine) (PEI) exhibits much broader 13C NMR resonances than the linear polymers poly(allylamine) (PAA) and poly(vinylamine) (PVA). These results are understood in terms of the low energy conformations calculated from molecular modeling studies. Three new ...

2006-03-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

361

Radiochemical separation of no-carrier-added {sup 177}Lu as produced via the {sup 176}Ybn,{gamma}{sup 177}Yb{yields}{sup 177}Lu process

The efficiency of the synthesized zeolite NaY from rice husk ash (RHA) in the removal of Cr(III) from aqueous solution was studied. Zeolite NaY was synthesized from RHA via seeding technique and the identification of its structure was done by X-ray Diffraction (XRD) technique and the elemental analysis was carried out by X-ray Fluorescence (XRF). The physicochemical properties which were related to the use of the zeolite NaY as a sorbent was also investigated. The synthesized zeolite NaY has higher cation exchange capacity (CEC) than the commercial zeolite NaY due to the higher amount of sodium content in the synthesized as well as the lower ratio of silica to alumina. The synthesized zeolite NaY together with the commercial one as comparison was used in the sorption of the Cr(III) in aqueous solution by batch sorption experiments. The kinetic study showed that the Cr(III) uptake by both zeolites were based on the pseudo second order model. Synthesized zeolite NaY ...

2007-01-01

362

Preparation of multication #alpha#-SiAlON containing strontium

The {sup 176}Ybn,{gamma}{sup 177}Yb-{beta}{sup -}{yields}{sup 177}Lu process was investigated to provide no-carrier-added (nca) {sup 177}Lu. The radiochemical separation of the {sup 177}Lu from the macro-amounts of the ytterbium target based on the cementation process, i.e. the selective extraction of Yb by Na(Hg) amalgam from Cl{sup -}/CH{sub 3}COO{sup -} electrolytes, followed by a final cation exchange purification. The cementation separation process provides a decontamination factor of Yb(III) of 10{sup 4}, the cation exchange purification adding a decontamination factor of >10{sup 2}. The nca {sup 177}Lu is available in radiochemically pure form despite the chemical similarity of the lanthanides with 75{+-}5% overall separation yield within 4-5 h. It can be used to synthesise nca {sup 177}Lu labelled radiotherapeuticals.

2000-09-15

363

FT-IR spectroscopic studies of hydrocarbon trapping in Ag{sup +}-ZSM-5 for gasoline engines under cold-start conditions

The possibility of having Sr as an interstitial metal cation in #alpha#-SiAlON has been investigated in two systems: a single-cation system (Si_3N_4-SrO-AlN) and a multication system (Si_3N_4-(Y_2O_3/SrO/CaO)-AlN). It was found that Sr alone does not form #alpha#-SiAlON and that Sr could only be accommodated in #alpha#-SiAlON in conjunction with Y and Ca. The Sr content of #alpha#-SiAlON increased as the total content of (Y + Ca) increased and appeared to reach a limit at 0.5 at.%, or 0.15 atom per #alpha#-SiAlON. Unexpectedly, some of the #alpha#-SiAlON that contained (Sr + Y + Ca) was present as laths or fibers with the c-axis perpendicular to the hot-press direction.

364

Electron spin resonance probe for the solvation of ionomer membranes and other microscopically heterogeneous systems. Cu[sup 2+] in nafion, sephadex and silica gel

A detailed study of adsorption of automobile exhaust hydrocarbons in Ag{sup +}-exchanged zeolites under cold-start conditions (room temperature and in the presence of water) was carried out with FT-IR spectroscopy, using toluene and propylene as probes. The results show that exchanged Ag{sup +} in zeolites is unique for trapping olefin and aromatic hydrocarbons due to its resistance to water adsorption. In contrast, exchanged Cu{sup 2+} in zeolites, which has good hydrocarbon trapping properties under dry conditions, does not trap hydrocarbons under wet conditions. Here, solvation of Cu{sup 2+} screens the interactions of the cation with adsorbed hydrocarbons. The results also show that, in addition to the nature of the cation, the structure of the zeolite also plays a role in hydrocarbon trapping. Aging at high temperatures, with water vapor (=10%) and SO{sub 2} (=15ppm), leads to a decrease of the trapping centers in the zeolites due to ...

2001-12-28

365

Crud removal performance with ion exchange resins in BWR plants

Cu[sup 2+] is a sensitive electron spin resonance (ESR) probe for the penetration of various polar solvents in membranes made of Nafion and as an indicator for the replacement of one solvent by another. The ESR parameters (g and [sup 63]Cu hyperfine tensors) can be translated into a structure of the solvent around the cation. The replacement of a solvent in the membrane by another depends on the polarity of the two solvents. The solvent with the largest dielectric constant, N-methylformamide (NMF), can be replaced by water but not by methanol or acetonitrile (dielectric constants 182, 78.5, 32.7, and 37.5, respectively). Preferential solvation of the cation by water in three water/acetonitrile mixtures (9:1, 1:1, and 1:9 by volume) in contact with silica gel, Sephadex, and Nafion has been observed in various degrees. Nafion is most selective, followed by Sephadex and by silica gel. The selectivity appears to be related to electrostatic ...

1992-01-01

366

Characteristics of ionic liquid-based electrolytes for chip type aluminum electrolytic capacitors

It is needless to say that one of the most important roles of the condensate demineralizer in Japanese boiling water reactors (BWR) is to eliminate such impurities during accidental occurrence of sea water leakage from condensate cooling system. Ion exchange resins packed in condensate demineralizer have also been expected to decrease crud, or corrosion products (CP) in condensate water in order to finally reduce activated corrosion products (ACP) in the reactor coolant loop. It is perceived that crud removal ability of a condensate demineralizer has been improved year by year. And we call this phenomenon as `Aging Effect`. Typical property changes of aged cation exchange resin consisted of an increase of water retention capacity and a change of surface texture. Based on these findings, we formulated a new concept and developed new gel type ion exchange resins for the better crud removal. The results from column tests using actual condensate water for approximately ...

1996-01-01

367

BIMETALLIC LITHIUM BOROHYDRIDES TOWARD REVERSIBLE HYDROGEN STORAGE

Since ionic liquids (ILs) possess several attractive properties, including chemical and thermal stability, nonflammability, high ionic conductivity, and negligible vapor pressure, a new electrolyte system based on ILs has been proposed for chip type aluminum electrolytic capacitors. Four ILs based on imidazolium/pyrrolidinium cations and maleate/phthalate anions have been synthesized and their thermal stabilities have been examined. The 25wt.% solutions of the four ILs in gamma-butyrolactone (GBL) solvent were prepared as electrolytes of chip type aluminum electrolytic capacitors. The conductivity, sparking voltage and thermal stability of these electrolytes have been systematically investigated. The results revealed that the four IL-based electrolytes exhibited high conductivity. Furthermore, the conductivity of maleate anion-based electrolytes is higher than that of phthalate anion-based electrolytes, whereas the high-temperature durability of phthalate ...

2006-06-19

368

A novel drug and gene co-delivery system based on Poly(epsilon-caprolactone)-Poly(ethylene glycol)-Poly(epsilon-caprolactone) grafted polyethyleneimine micelle.

Borohydrides such as LiBH{sub 4} have been studied as candidates for hydrogen storage because of their high hydrogen contents (18.4 wt% for LiBH{sub 4}). Limited success has been made in reducing the dehydrogenation temperature by adding reactants such as metals, metal oxides and metal halides. However, full rehydrogenation has not been realized because of multi-step decomposition processes and the stable intermediate species produced. It is suggested that adding second cation in LiBH{sub 4} may reduce the binding energy of B-H. The second cation may also provide the pathway for full rehydrogenation. In this work, several bimetallic borohydrides were synthesized using wet chemistry, high pressure reactive ball milling and sintering processes. The investigation found that the thermodynamic stability was reduced, but the full rehydrogenation is still a challenge. Although our experiments show the partial reversibility of the bimetallic ...

2010-10-21

369

Study on the use of zirconium phosphate for radioactive waste treatment

In this paper, we prepared a novel cationic self-assembled micelle from poly(epsilon-caprolactone)-poly(ethyl glycol)-poly(epsilon-caprolactone) grafted polyethyleneimine (PCEC-g-PEI). The PCEC-g-PEI micelles, formed by self-assembly method, had mean particle size of ca. 82 nm and zeta potential of +22.5 mV at 37 degrees C, and could efficiently transfer pGFP into HEK293 cells in vitro. Meanwhile, as a model hydrophobic chemotherapeutic drug, honokiol was loaded into PCEC-g-PEI micelles by direct dissolution method assisted by ultrasonication. The honokiol loaded cationic PCEC-g-PEI micelles could effectively adsorb DNA onto its surface, while it could release honokiol in an extended period in vitro. This study demonstrated a novel DNA and hydrophobic chemotherapeutic drug co-delivery system. PMID:21121283

2010-12-01

370

Studies on radioactive liquid waste treatment by reverse osmosis

Zirconium phosphate was one of the earliest inorganic ion-exchange suggested for removing strontium and cesium from aqueous nuclear waste. This paper studied ionic exchange to remove Cs-137 and Sr-90 by using different cationic of zirconium phosphate. In this case the parameters studied were the effect of temperature and ion concentration to percent up take and distribution coefficients. It is also conducted the study on column experiments to determine the breakthrough curves for Cs-137 and Sr-90. The result showed the potential of use of zirconium phosphate in radioactive waste treatment. (author)

1998-12-01

371

Studies on radioactive liquid waste treatment by reverse osmosis

Reverse osmosis is a simple process and has relatively high decontamination factor compared to other processes used for the treatment of radioactive liquid waste. Furthermore the quantity of secondary waste of this process is small. In this study, test solution containing nine elements such as cesium, strontium, cobalt etc. in chloride forms are treated by reverse osmosis. Permeate rate decreases as the increase of osmotic pressure of feed solution and is expressed by linear equation. Decontamination factor of cations of univalency is more than ten, and about one tenth of that of bivalency. Decontamination factors of all the elements used in this experiment are approximately estimated using the solution-diffusion model.

1982-06-01

372

Structural origin of optical bowing in semiconductor alloys p

Reverse osmosis is a simple process and has relatively high decontamination factor comparing to other processes used for the treatment of radioactive liquid waste. Furthermore the quantity of secondary waste of this process is small. In this study, test solution containing nine elements such as cesium, strontium, cobalt etc. in chloride forms are treated by reverse osmosis. Permeate rate decreases as the increase of osmotic pressure of feed solution and is expressed by linear equation. Decontamination factor of cations of univalency is more than ten, and about one tenth of that of bivalency. Decontamination factors of all the elements used in this experiment are approximately estimated using the solution-diffusion model. (author).

373

Structural origin of optical bowing in semiconductor alloys p

The principle of conservation and transferability of chemical bonds explains the recent discovery by extended x-ray absorption fine-structure measurements of two unequal anion-cation bond lengths R/sub A/C and R/sub B/C in A/sub x/B/sub 1-x/C zinc-blende semiconductor alloys despite the close adherence of the lattice constant to the average value (Vegard rule). This bond alternation, manifested as a structural distortion to a local chalcopyrite coordination around the anions, explains also most of the observed optical bowing in semiconductor alloys.

1983-08-22

374

Separation of carrier free "1"7"6","1"7"7W and "1"7"6","1"7"7Ta radionuclides produced in "1"6O activated holmium metal target

The principle of conservation and transferability of chemical bonds explains the recent discovery by extended x-ray absorption fine-structure measurements of two unequal anion-cation bond lengths R/sub A/C and R/sub B/C in A/sub x/B/sub 1-x/C zinc-blende semiconductor alloys despite the close adherence of the lattice constant to the average value (Vegard rule). This bond alternation, manifested as a structural distortion to a local chalcopyrite coordination around the anions, explains also most of the observed optical bowing in semiconductor alloys.

375

Preparation of monoclonal antibodies labelled by astatine

Carrier-free radioisotopes of tungsten, "1"7"6","1"7"7W, and their corresponding daughter radionuclides "1"7"6","1"7"7Ta, have been produced in holmium target by heavy ion activation with "1"6O"5"+ beam. An attempt has been made to separate these carrier-free radionuclides from bulk holmium target through LLX using cation exchanger HDEHP. (author)

2001-02-07

376

Partial oxidation of 2-propanol on perovskites

Astatine conversed into cationic form is shown to form stable complex with diethylenetriaminpentacetic acid. Due to this complex astatine joins RN_2 type monoclonal antibodies. More favorable conditions to prepare astatine labelled antibodies are found. Chromatographical analysis and electromigration experiments have shown that astatine is strongly retained in in-vitro biomolecule. Astatine did not escape from the labelled antibodies even in case of urea effect on them. Immune activity of astatine labelled antibodies remained similar in 20 h. 28 refs., 4 figs.

377

Interaction between flavonoid, quercetin and surfactant aggregates with different charges

Partial oxidation of 2-propanol was carried out on AB{sub 1-x}B`{sub x}O{sub 3} (A=Ba, B=Pb, Ce, Ti; B`=Bi, Sb and Cu) type perovskite oxides. Acetone was the major product observed on all the catalysts. All the catalysts underwent partial reduction during the reaction depending on the composition of the reactant, nature of the B site cation and the extent of substitution at B site. The catalytic activity has been correlated with the reducibility of the perovskite oxides determined from Temperature Programmed Reduction (TPR) studies. (orig.)

1998-12-31

378

British Library Electronic Table of Contents (United Kingdom)

The interactions of flavonoid, quercetin with sodium dodecyl sulfate (anionic surfactant) and cetyltrimethyl ammonium bromide (cationic surfactant) micelles were investigated. The average location site of quercetin in different micelles was determined by the cyclic voltammetry method with the aid of molecular optimization. The interaction parameters of quercetin with micelles of different charges such as binding constant K and normal binding energy DG were calculated. Furthermore, the morphologic change of the SDS and CTAB spherical micelles and rod-like micelles upon their interaction with quercetin was also observed.

2006-01-01

379

Inorganic chemistry of univalent astatine

First investigations of complex formation of At(I) with phosphorous organic compounds

A review is given of the state of knowledge of the chemistry of astatine with the oxidation number +1. According to the position in the periodic system, astatine has metalloidal properties. The existence of a singly-charged cation in acid solution and the complex formation reactions with halide ions (Cl"-, Br"-, and I"-), with pseudohalide ions (SCN"-, CN"-, C(CN)_3"-, and N_3"-), and with thioureas and their derivatives underline the metalloidal character of At(I). Optimal preparation conditions, chemical composition of astatine compounds, existence and stability regions of At(I) complexes, and stability constants have been investigated by means of electromigration in free electrolyte solutions.

380

First investigations of complex formation of At(I) with phosphorous organic compounds

Reaction of At(I) with triphenylphosphine, triethylphosphite and tri-n-octylphosphine oxide was investigated in ethanolic solution by means of electromigration. A cationic complex with triphenylphosphine was identified being stable at pH = 1,9 in the concentration range of the ligand between c = 10{sup -5} to 10{sup -3} M. At a higher ligand concentration and at pH>2, the reduction effect of phosphine is superimposed on the complex formation. Complex formation is confirmed by ligand exchange reactions with Br{sup -} and I{sup -}. A comparatively weak complex is formed by triethylphosphite and At(I). No compound is formed by tri-n-octylphosphine oxide and At(I). (orig.).

1989-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

381

Electron transfer with C_6_0 in the gas phase: an overview

Reaction of At(I) with triphenylphosphine, triethylphosphite and tri-n-octylphosphine oxide was investigated in ethanolic solution by means of electromigration. A cationic complex with triphenylphosphine was identified being stable at pH = 1,9 in the concentration range of the ligand between c = 10"-"5 to 10"-"3 M. At a higher ligand concentration and at pH>2, the reduction effect of phosphine is superimposed on the complex formation. Complex formation is confirmed by ligand exchange reactions with Br"- and I"-. A comparatively weak complex is formed by triethylphosphite and At(I). No compound is formed by tri-n-octylphosphine oxide and At(I). (orig.).

382

Effect of different fuels on the strontium hexaferrite nanopowder synthesized by a surfactant-assisted sol-gel auto-combustion method

Here I provide a brief overview of recent experimental gas-phase measurements using the Selected-Ion Flow Tube or SIFT technique at 294#+-#2 K with helium buffer gas at 0.35 Torr for reactions which remove electrons from the C_6_0 molecule or donate electrons to singly and multiply-charged C_6_0 cations. The results of these measurements have provided new insight into physicochemical aspects of electron transfer and have revealed the occurrence of unprecedented electron transfer reactions at thermal energies. (author).

1994-03-20

383

British Library Electronic Table of Contents (United Kingdom)

In this research a sol-gel auto-combustion route has been proposed to synthesize strontium hexaferrite nanopowder, using metal nitrates, ammonia as pH adjusting agent, n-decyltrimethylammonium bromide as a cationic surfactant and different fuels such as citric acid, glycine, acetylacetone and oxalic acid. The formation temperature of strontium hexaferrite and its crystallite size in presence of different fuels were compared together. The results showed the lowest formation temperature as well as the smallest crystallite size in the presence of citric acid as 900degreeC and 37.3nm respectively.

2007-01-01

384

Decontamination of building surface using clay suspension

British Library Electronic Table of Contents (United Kingdom)

The decontamination of the urban building surfaces, based on the covering of clay suspensions, has been studied. Contaminated samples for test purpose were prepared by application of radioactive solution which was extracted from the soil of 2 km zone of the Chernobyl Nuclear Power Plant(ChNPP). The cation converting conditions of clay suspensions were determined by the experiments of swelling and stability of the suspensions. According to the experimental results, the most effective clay suspension was the NH{sub 4}-type which had a 7.1 of decontamination factor(DF) on Cs and 4.5 of DF on total nuclides after 3 times covering on slate.

1994-07-01

385

Cleavable surfactants

The review covers the development within the field of cleavable surfactants since 2003. Cleavable surfactants are amphiphiles in which a weak linkage has been deliberately inserted, normally, but not always, between the hydrophobic tail and the polar headgroup. Alkali labile linkages that have been used for the purpose include normal ester bonds, betaine esters, and carbonates. Ketals and ortho esters are example of bonds that are susceptible to acid hydrolysis. Several investigations deal with cationic ester-containing surfactants, both monomeric and dimeric species, the latter being gemini surfactants. Ester, amide and carbonate containing surfactants have been investigated with respect to enzyme catalyzed hydrolysis. The main incentive for the development of novel cleavable surfactants ...

2007-01-01

386

Change in the chemical composition and surface properties of high-silica zeolites in activating treatments and during a catalytic reaction

Catalysis over activated high silica zeolites

The surface composition and composition near the surface and properties of high-silica zeolites of the TsVK-1 type were studied by XPES, IRS, and low-temperature adsorption of N/sub 2/. It was found that changing the sequence of operations during preparation of the H form of the zeolites results in a different set of acid centers on their surface, caused by migration of cations into the bulk of the zeolites. Migration of elements is also observed during the catalytic reaction of conversion of ethanol.

1988-08-01

387

Removal of radioactive ions from nuclear waste solutions by electrodialysis

A process is provided for conducting organic compound conversion over a catalyst composition comprising a specially treated crystalline zeolite having a high initial silica-to-alumina mole ratio, said zeolite having been synthesized from a reaction mixture comprising a diamine as a cation source. The treatment of the zeolite material comprises the sequential steps of reacting the zeolite with a dilute hydrogen fluoride solution, contacting the hydrogen fluoride solution reacted material with aluminum chloride vapor, and then treating the aluminum chloride contacted material to convert it to hydrogen form.

1985-05-07

388

Modification of ion-exchange resin composition for the removal of Gd of higher (15 ppm) concentration from moderator system of 540 MWe PHWRs

Removal of radioactive ions was studied from low and medium level radioactive waste solutions by electrodialysis using ion exchange membranes. The test solutions contained "1"3"7Cs"+, "1"0"6Ru"3"+ or fission products (F.P.) as active ions and NaCl, Na_2SO_4 or Ca(NO_3)_2 as inactive coexisting salts. The decontamination factor of the active ions was in the order: "1"3"7Cs"+ (greater than 99%) > "9"0Sr"2"+ > F.P. > "1"0"6Ru"3"+. The dialysis time required to attain the saturation was the shortest for monovalent cations K"+, Cs"+ and Na"+, intermediate for divalent cation Sr"2"+, and the longest for trivalent cation Ru"3"+. The ratio of the decontamination factor of an active ion eta sub( a) to the desalination factor of an inactive ion eta sub( b) was nearly equal to unity for "2"4Na, "4"2K, "1"3"7Cs and "9"0Sr. On the other hand, the apparent selective permeability of an active ion (A"+) against Na"+ ion, T ...

389

Ion backscattering, channeling and nuclear reaction analysis study of passive films formed on FeCrNi and FeCrNiMo (100) single crystals

Addition of Gadolinium Nitrate as chemical shim to moderator heavy water of 540 MWe PHWR, at 15 mg/kg level (at a pH of 5.0) is practiced for reactor shutdown purposes. Presently a strong acid cation exchanger column is used for this purpose. During this operation, the moderator pH of 3.8, with the IX column outlet pH of ?3.5-3.6 was observed against the technical specification demand that when Gd is present, the pH of moderator must be in the range of 5.0-5.5. In order to achieve an iso-pH regime during Gd removal, studies were conducted using a mixed bed of strong acid cation resin plus a weak base anion resin (loaded in the volume ratio of 1 : 6), backed up in the same column (bottom most layer) by a 5 % nitric acid loaded weak base resin and topped by a strong acid cation resin (uppermost layer) simulating system flow velocity and percentage loading of resin. Using such a column it is demonstrated that Gd removal could ...

2006-11-13

390

Ion backscattering, channeling and nuclear reaction analysis study of passive films formed on FeCrNi and FeCrNiMo (100) single crystals

The compositions of passive films formed on Fe-17Fr-13Ni (at. %) and Fe-18.5Cr-14Ni-1.5Mo (100) single crystals have been determined and the structure of the alloy under the film has been investigated. The alloys were passivated in 0.05M H{sub 2}SO{sub 4} at 250 mV/SHE for 30 min. The oxygen content was measured by nuclear microanalysis using the {sup 16}O(d,p) {sup 17}O* reaction. The oxygen content in the passive film is similar for the two alloys and equal to (12{plus minus}2) 10{sup 15} O/cm{sup 2}. The cationic compositions of the passive films have been determined by {sup 4}He channeling at two incident beam energies: 0.8 and 2.0 MeV. For the two alloys studied, a total cation content of (5{plus minus}2)10{sup 15} at/cm{sup 2} is found in the passive films. The corresponding thickness is about 12 A. There is an excess of oxygen, which can be attributed to the presence of hydroxyls and sulfate. A strong chromium enrichment is found in the ...

1990-01-01

391

Extracellular ATP4- promotes cation fluxes in the J774 mouse macrophage cell line

The compositions of passive films formed on Fe-17Fr-13Ni (at. %) and Fe-18.5Cr-14Ni-1.5Mo (100) single crystals have been determined and the structure of the alloy under the film has been investigated. The alloys were passivated in 0.05M H_2SO_4 at 250 mV/SHE for 30 min. The oxygen content was measured by nuclear microanalysis using the "1"6O(d,p) "1"7O* reaction. The oxygen content in the passive film is similar for the two alloys and equal to (12#+-#2) 10"1"5 O/cm"2. The cationic compositions of the passive films have been determined by "4He channeling at two incident beam energies: 0.8 and 2.0 MeV. For the two alloys studied, a total cation content of (5#+-#2)10"1"5 at/cm"2 is found in the passive films. The corresponding thickness is about 12 A. There is an excess of oxygen, which can be attributed to the presence of hydroxyls and sulfate. A strong chromium enrichment is found in the passive film formed on both alloys: chromium represents ...

1989-09-24

392

Effects of inorganic cation templates on octahedral molecular sieves of manganese oxide

Extracellular ATP stimulates transmembrane ion fluxes in the mouse macrophage cell line J774. In the presence of Mg2+, nonhydrolyzable ATP analogs and other purine and pyrimidine nucleotides do not elicit this response, suggesting the presence of a specific receptor for ATP on the macrophage plasma membrane. One candidate for such a receptor is the ecto-ATPase expressed on these cells. We, therefore, investigated the role of this enzyme in ATP-induced /sup 86/Rb+ efflux in J774 cells. The ecto-ATPase had a broad nucleotide specificity and did not hydrolyze extracellular ATP in the absence of divalent cations. /sup 86/Rb+ efflux was not blocked by inhibition of the ecto-ATPase and did not require Ca2+ or Mg2+. In fact, ATP-stimulated /sup 86/Rb+ efflux was inhibited by Mg2+ and correlated with the availability of ATP4- in the medium. In the absence of divalent cations, the slowly hydrolyzable ATP analogs adenosine 5'-(beta, ...

1987-03-05

393

Detection by cationized /sup 125/I-cytochrome C of proteoglycans (PG) transferred to nylon

Five hydrated inorganic divalent cations, Mg[sup 2+], Co[sup 2+], Ni[sup 2+], Cu[sup 2+], and Zn[sup 2+], have successfully been used as templates for the synthesis of manganese oxide octahedral molecular sieves (OMS-1) having the todorokite structure. The OMS-1 samples have been well characterized by X-ray diffraction, differential scanning calorimetry, thermogravimetric analysis, scanning electron microscopy/energy dispersive X-ray studies, inductively coupled plasma analysis, electron paramagnetic resonance, Fourier transform infrared spectroscopy, thiosulfate titration, and cyclohexane sorption. Catalytic CO oxidation and 2-propanol decomposition were carried out. Results show that these OMS-1 samples with a tunnel size of about 6.9 angstroms are crystalline and chemically pure. They have the following formulas: Mg[sub 3.17]Mn[sub 5.05]O[sub 12] [center dot] 4.52H[sub 2]O, Co[sub 1.84]Mn[sub 5.59]O[sub 12] [center dot] 3.45H[sub 2]O, Ni[sub 1.64]Mn[sub ...

1994-11-30

394

Azathia crown ethers carrying pyrene pendant as receptor molecules for metal sensor systems

Cytochrome c, labeled with /sup 125/I, has been used by us for staining glycosaminoglycans (GAG) separated by electrophoresis on cellulose acetate strips. As GAG between 1-10 ng could be quantified by autoradiography and densitometry, the reagent is approximately 100-fold more sensitive than currently used non-radiolabeled stains. The authors extend now the use of radiolabeled cytochrome c to the quantification of PG transblotted to solid supports subsequent to separation on polyacrylamine slab gels. Dot blotting used for exploring optimal conditions for detecting PG indicated that because of low background positively charged Nylon 66 was superior to nitrocellulose. Increasing the positive charge of the staining reagent by cationization decreased background radiation even further so that 1 ng PG could be seen readily after 5 hrs of autoradiography. Use of cationized /sup 125/I-cytochrome c has been made in detecting PG of bovine fetal ...

1986-05-01

395

Hydration of swelling clay and bacteria interaction. An experimental in situ reaction study; Hydratation des argiles gonflantes et influence des bacteries. Etude experimentale de reaction in situ

A series of crown ethers carrying a pyrene group with nitrogen-sulfur donor atoms, that differ in having three, four and five sulfur atoms in the macrocycle was designed and synthesized by the reaction of the corresponding macrocyclic compound and 1-bromomethylpyrene. The influence of metal cations such as Mn2+, Fe2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+, Pb2+ and Al3+ on the spectroscopic properties of the ligands was investigated in acetonitrile-dichloromethane (1:1) by means of absorption and emission spectrometry. Absorption spectra show isosbestic points in the spectrophotometric titration of Fe2+, Zn2+, Cu2+, Pb2+ and Hg2+. The results of spectrophotometric titration experiments disclosed the complexation compositions and complex stability constants of the novel ligands with Fe2+, Zn2+, Cu2+, Pb2+ and Hg2+ cations. The monoazatetrathia crown ether showed good sensitivity for Cu2+ with linearity in the range 5.0x10-7-2.5x10-6 M and ...

2011-04-01

396

{beta}-delayed proton decays near the proton drip line

This study reports on the physical-chemical behaviour of swelling di-octahedral clays (smectites) and their interaction with aqueous solutions and bacteria (Shewanella putrefaciens). Experimental results are presented for compacted clays, hydrated under confined volume conditions, using a new type of reaction-cell (the 'wet-cell' of Warr and Hoffman, 2004) that was designed for in situ X-ray diffraction (XRD) measurement. For comparison, dispersed clay systems were studied using standard batch solutions subjected to varying degrees of agitation. The combination of time-dependent in situ XRD measurements with gravimetric measurements and calculated diffraction patterns using the CALCMIX software (Plancon and Drits, 1999) allowed to successful quantification of the dynamics of water uptake and storage. This analytical procedure combined with published water vapour adsorption data enabled determination of the abundance of structured water layers, developed in the ...

2008-01-15

397

Correlation between proton pumping and the bacteriorhodopsin photocycle

We briefly reviewed and summarized the experimental study on {beta}-delayed proton decays published by our group over the last 8 years, namely the experimental observation of {beta}-delayed proton decays of nine new nuclides in the rare-earth region near the proton drip line and five nuclides in the mass 90 region with N{approx}Z by utilizing the p-{gamma} coincidence technique in combination with a He-jet tape transport system. In addition, important technical details of the experiments were provided. The experimental results were compared to the theoretical predictions of some nuclear models, resulting in the following conclusions. (1) The experimental half-lives for {sup 85}Mo, {sup 92}Rh, as well as the predicted 'waiting point' nuclei {sup 89}Ru and {sup 93}Pd were 5-10 times longer than the macroscopic-microscopic model predictions of Moeller et al. [At. Data Nucl. Data Tables 66,131(1997)]. These ...

2005-05-01

398

Accelerators for proton and heavy ion radiotherapy

In an attempt to establish a relationship between proton pumping and the photocycle intermediates of bacteriorhodopsin, we have studied the effects of pH and temperature of flash-induced proton pumping and the photointermediates O/sub 640/ and M/sub 412/. The relative quantum yield of flash-induced proton pumping is both pH and temperature dependent. It is high in the acid pH range and at low temperatures but decreases in the basic pH range and at high temperatures. The decay of M/sub 412/ is biphasic. The amplitude of the slowly decaying component (M/sup s/) was found to be pH dependent with a pK similar to that of the ..delta..pH. The pH dependence of the fast-decaying component (M/sup f/) is opposite to that of M/sup s/ and ..delta..pH. Like that of M/sup s/, the amplitude of O/sub 640/ is high in the acid pH range, but unlike the amplitude of M/sup s/, it declines very rapidly at pHs greater than 6.5; the amplitude of ...

1984-11-01

399

ANALYSIS OF ACCELERATOR BASED NEUTRON SPECTRA FOR BNCT USING PROTON RECOIL SPECTROSCOPY

The construction of Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences was completed in December 1993. HIMAC consists of an injector linac, two synchrotron rings, a high energy beam transport system and a beam irradiation system. Its accelerator parameters are based on the medical requirement, and helium, carbon, neon, silicon and argon were selected as the accelerated ion species. It has 3 therapy rooms (A{approx}C). Room A has a vertical irradiation system, Room C horizontal and Room B both vertical and horizontal. Two rings can supply beams independently to the vertical and horizontal irradiation systems. Clinical trial started on June 21 1994, after several basic biological and physics experiments lasting about 2 months. Cancer is the top cause of death in Japan since 1981, and people expect good treatment results at HIMAC. Proton and heavy ion radiotherapy has the advantage of dose distribution and biological ...

1995-03-01

400

#beta#-delayed proton decays near the proton drip line

Boron Neutron Capture Therapy (BNCT) is a promising binary treatment modality for high-grade primary brain tumors (glioblastoma multiforme, GM) and other cancers. BNCT employs a boron-10 containing compound that preferentially accumulates in the cancer cells in the brain. Upon neutron capture by {sup 10}B energetic alpha particles and triton released at the absorption site kill the cancer cell. In order to gain penetration depth in the brain Fairchild proposed, for this purpose, the use of energetic epithermal neutrons at about 10 keV. Phase I/II clinical trials of BNCT for GM are underway at the Brookhaven Medical Research Reactor (BMRR) and at the MIT Reactor, using these nuclear reactors as the source for epithermal neutrons. In light of the limitations of new reactor installations, e.g. cost, safety and licensing, and limited capability for modulating the reactor based neutron beam energy spectra alternative neutron sources are being contemplated for wider implementation of this ...

1998-11-06

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

401

#beta#-delayed proton decays near the proton drip line

The experimental study on #beta#-delayed proton decays near the proton drip line published by our group over the last 8 years were reviewed and summarized briefly, including first observation of 9 precursors in the rare-earth region and new measurements of 5 nuclei in the mass-90 region near N-Z line with the aid of the 'p-#gamma#' coincidence in combination with a He-jet tape transport system. Systematically comparing the experimental data with the current nuclear-model predictions, following points were represented. (1) the experimental half-lives for "8"5Mo and "9"2Rh as well as the predicted 'waiting point' nuclei "8"9Ru and "9"3Pd are 5-10 times longer than the macroscopic-microscopic model predictions given by Moeller et al. It considerably influences the prediction of mass abundances of the nuclides produced in rp-process. (2) The current-model predictions are not consistent with the experimental spin-parity assignments of the ...

2004-12-01

402

Yield and excitation function measurements of some nuclear reactions on natural thallium induced by protons leading to the production of medical radioisotopes {sup 201}Tl and {sup 203}Pb

We briefly reviewed and summarized the experimental study on #beta#-delayed proton decays published by our group over the last 8 years, namely the experimental observation of #beta#-delayed proton decays of nine new nuclides in the rare-earth region near the proton drip line and five nuclides in the mass 90 region with N#approx#Z by utilizing the p-#gamma# coincidence technique in combination with a He-jet tape transport system. In addition, important technical details of the experiments were provided. The experimental results were compared to the theoretical predictions of some nuclear models, resulting in the following conclusions. (1) The experimental half-lives for "8"5Mo, "9"2Rh, as well as the predicted 'waiting point' nuclei "8"9Ru and "9"3Pd were 5-10 times longer than the macroscopic-microscopic model predictions of Moeller et al. [At. Data Nucl. Data Tables 66,131(1997)]. These data considerably influenced the ...

2005-05-01

403

Two-dimensional analysis of energy conversion efficiency for a traveling wave direct energy convertor

Excitation functions for {sup 201}Pb, {sup 202m}Pb, {sup 203}Pb and {sup 204m}Pb radionuclides which are formed via proton induced reactions with natural thallium target have been measured from their respective threshold (E{sub thr}) to 27.5 MeV using activation technique. Natural copper foils were used to monitor the cyclotron beam. The integral yields (MBq/{mu}A h) of the produced radionuclides were calculated from the measured excitation functions. The optimum proton energy range for the production of {sup 203}Pb with low amount of impurities is (16-10 MeV) after 5 h of EOB. The experimental cross-sections for {sup nat}Tl(p,xn) reactions were compared with the cross-sections recommended by the IAEA and with earlier published data when it was possible. (orig.)

2007-07-01

404

Two dimensional NMR and NMR relaxation studies of coal structure. Progress report, July 1, 1992--September 30, 1992

Two-dimensional calculations are performed to obtain the conversion efficiency of traveling wave direct energy convertor adopted in a conceptual design of field reversed configuration D-"3He fusion reactor ARTEMIS. For fusion-born 14.67MeV protons, the efficiency obtained is very small compared with that from one-dimensional analysis. This is because the effective electric field for deceleration of the proton is smaller due to distortion of potentials near girds used to excite the traveling wave and because some fractions of the incident proton beams are inevitably lost to the grids with high energy. To increase the efficiency, the potentials may have to be increased. It seems from the two-dimensional analysis performed here that the conversion efficiency obtainable is less than about 60% with the maximum potential of about 6MV, while the corresponding values from the one-dimensional analysis are about 80% and 1.5MV, ...

405

The cluster structure of the inner crust of neutron stars in the Hartree-Fock-Bogoliubov approach

This report covers the progress made on the title project for the project period. Four major areas of inquiry are being pursued. Advanced solid state NMR methods are being developed to assay the distribution of the various important functional groups that determine the reactivity of coals. Special attention is being paid to methods that are compatible with the very high magic angle sample spinning rates needed for operation at the high magnetic field strengths available today. Polarization inversion methods utilizing the difference in heat capacities of small groups of spins are particularly promising. Methods combining proton-proton spin diffusion with {sup 13}C CPMAS readout are being developed to determine the connectivity of functional groups in coals in a high sensitivity relay type of experiment. Additional work is aimed at delineating the role of methyl group rotation in the proton NMR relaxation behavior of coals.

1992-11-25

406

Study of praseodymium complexing with ethylenediaminetetraacetic acid by proton magnetic resonance

We analyse how the structure of the inner curst is influenced by the pairing correlations. The inner-crust matter, formed by nuclear clusters immersed in a superfluid neutron gas and ultra-relativistic electrons, is treated in the Wigner-Seitz approximation. The properties of the Wigner-Seitz cells, i.e., their neutron to proton ratio and their radius at a given baryonic density, are obtained from the energy minimization at beta equilibrium. To obtain the binding energy of baryonic matter we perform Skyrme-HFB calculations with zero-range density-dependent pairing forces of various intensities. We find that the Wigner-Seitz cells have much smaller numbers of protons compared to previous calculations. For the dense cells the binding energy of the configurations with small proton numbers do not converge to a well-defined minimum value which precludes the determination of their structure. We show that for these cells there is ...

2011-01-01

407

Replacement of leucine-93 by alanine or threonine slows down the decay of the N and O intermediates in the photocycle of bacteriorhodopsin: Implications for proton uptake and 13-cis-retinal----all-trans-retinal reisomerization

The method of proton magnetic resonance (PMR) has been used to study the mechanism of reaction of complexing of paramagnetic Pr/sup 3 +/ ion with ethylenediaminetetra acetic acid (EDTA). The influence of medium acidity (pH5-12), EDTA/Pr ratio varying from 1 to 50, Pr/sup 3 +/ ion concentration (from 5x10/sup -3/ to 3x10/sup -1/ g-ion/l) and temperature (8-98 deg C) on chemical shifts and broadening of signals of EDTA molecule protons is investigated. Data on ratio of components, coordination and stability of forming complexes are obtained. The existence of two types of complexes with the Pr/EDTA ratio equal to 1:1 and 1:2 has been found. Equimolecular complex (1:1) is stable all over the studied temperature interval in contrast to the complex 1:2 for which at 50 deg C fast extrasphere exchange (Pr EDTA)EDTA * + EDTA/sup 0/ reversible (PrEDTA)EDTA/sup 0/ + EDTA * is observed, while at t=98 deg C intrasphere exchange (PrEDTA)EDTA * reversible ...

1983-05-01

408

Proton exchange membrane materials for the advancement of direct methanol fuel-cell technology

The authors report that the replacement of Leu-93 in bacteriorhodopsin by Ala (L93A) or Thr (L93T) slows down the photocycle by approximately 100-fold relative to wild-type bacteriorhodopsin. Time-resolved visible absorption spectroscopy and resonance Raman experiments, respectively, show the presence of long-lived O-like and N-like intermediates in the photocycles of the above mutants. We infer the existence of an equilibrium between the N and O intermediates in the photocycles of these mutants. The L93A and L93T mutants exhibit normal proton pumping under continuous illumination, suggesting that the decay of the N and/or O intermediate, and consequently, proton translocation, can be accelerated by the absorption of a second photon. Since the 13-cis----all-trans reisomerization of retinal is completed during the decay of the N and O intermediates, they conclude that the interaction of Leu-93 with retinal is important in this phase of the ...

1991-08-01

409

Population of nuclei close to N=Z line for A{approx}100 through emission of complex fragments and light charged particles

A new class of hybrid organic-inorganic materials, and methods of synthesis, that can be used as a proton exchange membrane in a direct methanol fuel cell. In contrast with Nafion.RTM. PEM materials, which have random sulfonation, the new class of materials have ordered sulfonation achieved through self-assembly of alternating polyimide segments of different molecular weights comprising, for example, highly sulfonated hydrophilic PDA-DASA polyimide segment alternating with an unsulfonated hydrophobic 6FDA-DAS polyimide segment. An inorganic phase, e.g., 0.5 5 wt % TEOS, can be incorporated in the sulfonated polyimide copolymer to further improve its properties. The new materials exhibit reduced swelling when exposed to water, increased thermal stability, and decreased O.sub.2 and H.sub.2 gas permeability, while retaining proton conductivities similar to Nafion.RTM.. These improved properties may allow direct methanol fuel cells to operate at ...

2006-04-04

410

Physicochemical study of poly(ether ether ketone) electrolyte membranes sulfonated with mixtures of fuming sulfuric acid and sulfuric acid for direct methanol fuel cell application

High spin states of the proton rich nuclei in the mass region A {approx} 100 have been studied at the GASP spectrometer through the evaporation of light charged particles and heavier ions detected in the 4{pi} Si-ball Isis. Rear side injection and pulse shape analysis have allowed a good discrimination among protons, alpha particles and heavy ions up to C. Of the several nuclei populated in the reactions we will discuss here the high spin states of {sup 105} Sn. In addition to an extension of the spherical level, scheme, a regular sequence of dipole transitions has been found, The states of the dipole band are suggested to be built on a neutron h{sup 2}{sub 11/2} excitation coupled to proton particle-hole states, which polarize the core to a slightly prolate shape. The experimental results are in agreement with the prediction of tilted axis cranking calculations, which satisfactorily explain the properties of the band. ...

1997-12-31

411

Optimization of Integrated Luminosity of the Fermilab Tevatron Collider

Sulfonated poly(ether ether ketone) (SPEEK) membranes with various degrees of sulfonation (DS) have been prepared as a potential membrane material for proton exchange membrane by sulfonation process using mixtures of (15-30% concentration) fuming sulfuric acid and (95-98%) concentrated sulfuric acid as the sulfonating agent. The sulfonation process was conducted at room temperature by varying the acid ratio and reaction time. The produced membranes were then characterized by evaluating the ion exchange capacity (IEC), water uptake, thermal stability, proton conductivity and methanol permeability as a function of degree of sulfonation. The proton conductivity of the sulfonated PEEK membranes with various DS was within the magnitude of 10"-"3 and 10"-"2 S cm"-"1 at room temperature and the methanol permeability was in the range of 3.45 x 10"-"7 to 2.73 x 10"-"6 cm"2 s"-"1. The overall membrane performance of the SPEEK ...

2007-07-15

412

Nuclear multifragmentation experiment at the KEK 12 GeV PS. The first results of the KEK-PS E337 experiment

We present the strategy which has been used recently to optimize integrated luminosity at the Fermilab Tevatron proton-antiproton collider. We use a relatively simple model where we keep the proton intensity fixed, use parameters from fits to the luminosity decay of recent stores as a function of initial antiproton intensity (stash size), and vary the stash size to optimize the integrated luminosity per week. The model assumes a fixed rate of antiproton production, that a store is terminated as soon as the target stash size for the next store is reached, and that the only downtime is due to store turn-around time. An optimal range of stash sizes is predicted. Since the start of Tevatron operations based on this procedure, we have seen an improvement of approximately 35% in integrated luminosity. Other recent operational improvements have been achieved by decreasing the shot-setup time and by reducing beam-beam effects by making the ...

2009-01-01

413

Measurements of single and double spin asymmetry in pp elastic scattering in the CNI region with a polarized atomic hydrogen gas jet target

A KEK-PS experiment E337 `Angular correlation of intermediate mass fragments emitted from the target multifragmentation reactions with 12 GeV protons` is an extension of the E288 performed a few years ago. The E288 revealed that the proton-induced target multifragmentation reactions at 12 GeV showed quite interesting phenomena such as 70 degree peaking angular distributions for intermediate mass fragments. In December, 1955, the test experiment with 12 GeV protons was started at KEK using this newly constructed counter array of 37 Bragg Curve Counters. The main production experiment was performed in April and May in 1996 after debugging the new counter system and DAQ system, as well as EP1-B beam line. Data with Au, Tm, Sm and Ag targets were successfully accumulated. The data are in the analysis stage, and several interesting features of high energy nuclear reactions have already been seen. (G.K.)

1997-05-01

414

Full Calculation of Clumpiness Boost factors for Antimatter Cosmic Rays in the light of \\LambdaCDM N-body simulation results

Precise measurements of the single spin asymmetry AN, and the double spin asymmetry ANN, in proton-proton (pp) elastic scattering in the region of four-momentum transfer squared 0.0012 have been performed using a polarized atomic hydrogen gas jet target and the Relativistic Heavy Ion Collider (RHIC) polarized proton beam. We present measurements of AN and ANN at center-of-mass energies ?(s)=6.8 and 13.7 GeV. These spin-dependent observables are sensitive to the poorly known hadronic spin-dependent amplitudes. Comparing AN at different energies, a ?(s) dependence of the hadronic single spin-flip amplitude is suggested. A hadronic double spin-flip amplitude from the ANN data is consistent with zero within a 2-? level. We also present ??T, estimated from the measured ANN data. The results for ??T are consistent with zero. Our results provide significant constraints toward a comprehensive understanding of the reaction mechanism for pp elastic ...

2009-05-01

415

Formation of the Neutron Donor C13 in AGB Stars by Overshoot and Rotation

Anti-proton and positron Galactic cosmic ray (GCR) spectra are among the key targets for indirect detection of dark matter (DM). The boost factors, corresponding to an enhancement of the signal|linked to the clumpiness properties of the dark matter distribution|, have been taken as high as thousands in the past. The dramatic impact of these boost factors for indirect detection of antiparticles, for instance with the PAMELA satellite or the coming AMS-02 experiment, asks for their detailed calculation. We take into account the state-of-the-art results of high resolution N-body dark matter simulations to calculate the most likely energy dependent boost factors|linked to the GCR propagation properties|, for anti-protons and positrons. The results from extreme, but still possible, configurations of the clumpy dark matter component is also discussed. Starting from the mass and space distributions of sub-halos, the anti-proton ...

2007-01-01

416

Extension of QMD to the relativistic region and the calculation of proton induced reactions

(abridged) Observations clearly show that low-mass AGB stars can provide a nucleosynthesis site of the s-process. Recent stellar evolution models indicate that radiative burning of C13 between thermal pulses in low-mass AGB stars may indeed provide the needed neutrons. Some mixing between the proton-rich envelope and the carbon-rich core may lead to the production of C13. However, the responsible physical mechanism is not yet unambiguously identified. We present stellar model calculations with overshoot and rotation. Overshoot, with a time-dependent and exponentially decaying efficiency, leads to a partial mixture of protons and C12 during the third dredge-up. According to the depth-dependent ratio of protons and C12, a small C13-pocket forms underneath a N14-rich layer. Overshoot does not allow for any mixing during the interpulse phase. Rotation introduces mixing driven by large angular velocity gradients which form at ...

2000-01-01

417

Evaluation of the humidification requirements of new proton exchange membranes for fuel cells

When quantum molecular dynamics (QMD) is applied to the nuclear reactions in theory of relativity region, a number of problems arise, and in order to solve them, the prescription of the extension of ordinary nonrelativistic QMD is introduced, and the analysis of proton incidence reaction by using it is shown. By introducing the interaction corresponding to Lorentz transformation, the problems were solved. QMD is the semiclassical simulation that treats the motion of nucleons represented by Gauss wave packet. The motion of wave packet center is expressed by Newton equations and two-nucleon collision. The introduction of the interaction corresponding to Lorentz transformation is explained. As the result of the introduction, through the relative distance of two particles, the interaction becomes to depend on momentum. The phase distribution function of one body corresponding to Lorentz transformation is used for calculating the final state Pauli effect of collision ...

1995-06-01

418

Donut-shaped high-dose configuration for proton beam radiation therapy

Measurements of PEM fuel cell device performance were made with different gas inlet temperatures and relative humidity using a newly-designed test fixture. Significant improvement in device performance was observed when the fuel inlet temperature was increased above the operating temperature of the cell. These measurements were then correlated to a model to describe energy and mass transport processes. Proton exchange membrane (PEM), fuel cells--the focus of this study--use an ion conducting polymer, especially polyperfluorosulfonic acid materials. These polymer materials, when imbibed with water, exhibit solution-like properties, but because the anions are chemically bound to the polymeric structure, the electrolyte is contained. Importantly, product water removal is simplified, as electrolyte dilution is not a concern. However, the proton transport rate is a function of the polymer geometry, which is set, in part, by the polymer water ...

1995-05-01

419

Donut-shaped high-dose configuration for proton beam radiation therapy

Background: the authors report on the conception and first clinical application of a donut-shaped high-dose configuration for proton therapy (PT). This approach allows one to intensify target volume dose coverage for targets encompassing a critical, dose-limiting structure - like here, the cauda equina -, whilst delivering minimal dose to other healthy structures surrounding the target, thereby reducing the integral dose. Methods and results: intensity-modulated PT methods (IMPT) for spot scanning were applied to create and deliver a donut-shaped high-dose configuration with protons, allowing treating > 75% of the target with at least 95% of the prescribed dose of 72.8 CGE, whilst restricting dose to the cauda equina to 60-65 CGE. Integral dose was lower by a factor of 3.3 as compared to intensity-modulated radiotherapy with photons (IMXT). Conclusion: IMPT and spot scanning technology allow a potentially clinically useful approach which ...

2005-01-01

420

Diffuse $\\gamma$-rays and $\\bar{p}$ flux from dark matter annihilation -- a model for consistent results with EGRET and cosmic ray data

Background: the authors report on the conception and first clinical application of a donut-shaped high-dose configuration for proton therapy (PT). This approach allows one to intensify target volume dose coverage for targets encompassing a critical, dose-limiting structure - like here, the cauda equina -, whilst delivering minimal dose to other healthy structures surrounding the target, thereby reducing the integral dose. Methods and results: intensity-modulated PT methods (IMPT) for spot scanning were applied to create and deliver a donut-shaped high-dose configuration with protons, allowing treating > 75% of the target with at least 95% of the prescribed dose of 72.8 CGE, whilst restricting dose to the cauda equina to 60-65 CGE. Integral dose was lower by a factor of 3.3 as compared to intensity-modulated radiotherapy with photons (IMXT). Conclusion: IMPT and spot scanning technology allow a potentially clinically useful approach which is ...

2005-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

421

Dependence of proton beam polarization on ion source transition configurations

In this work we develop a new propagation model for the Galactic cosmic rays based on the GALPROP code, including contributions from dark matter annihilation. The model predicts compatible Galactic diffuse $\\gamma$ ray spectra with EGRET data in all sky regions. It also gives consistent results of the diffuse $\\gamma$ ray longitude and latitude distributions. Further the results for B/C, $^{10}$Be/$^9$Be, proton, electron and antiproton spectra are also consistent with cosmic ray measurements. In the model we have taken a universal proton spectrum throughout the Galaxy without introducing large fluctuation for the proton energy loss is negligible. The dark matter annihilation signals are `boosted' after taking the contribution from subhalos into account. Another interesting feature of the model is that it gives better description of the diffuse $\\gamma$ rays when taking the source distribution compatible with supernova ...

2007-01-01

422

Construction and Calibration of the Laser Alignment System for the CMS Tracker

The polarization of extracted SATURNE II proton beam as a function of different ion source configurations was studied. Two distinct experiments were necessary for this purpose. In the first one, the left-right instrumental asymmetry of the beam polarimeter was determined using an unpolarized beam. In the second one this correction factor was applied to asymmetries measured with the beam from the polarized ion source in all polarization states. The measurements were carried out at the proton beam kinetic energy 0.80 GeV, where the pp-elastic scattering analyzing power is near its maximum. The results confirmed that the two so-called ``unpolarized states`` of the source were polarized to several percent, whereas the absolute values of the beam polarizations in the so-called ``polarized states`` were equal and opposite. It was observed that the hexapole lens of the ion source produced beam polarization in the absence of any transition. The beam ...

1997-11-11

423

A new measurement of the antiproton-to-proton flux ratio up to 100 GeV in the cosmic radiation

The CMS detector (Compact Muon Solenoid) is under construction at one of the four proton-proton interaction points of the LHC (Large Hadron Collider) at CERN, the European Organization for Nuclear Research (Geneva, Switzerland). The inner tracking system of the CMS experiment consisting of silicon detectors will have a diameter of 2.4 m and a length of 5.4 m representing the largest silicon tracker ever. About 15000 silicon strip modules create an active silicon area of 200 m2 to detect charged particles from proton collisions. They are placed on a rigid carbon fibre structure, providing stability within the working conditions of a 4 T solenoid magnetic field at ?10oC. Knowledge of the position of the silicon detectors at the level of 100 ?m is needed for an efficient pattern recognition of charged particle tracks. Metrology methods are used to survey tracker subdetectors and the integrated Laser Alignment System (LAS) provides absolute ...

2006-01-01

424

A fluorescent aminolipid from a green photosynthetic bacterium

A new measurement of the cosmic ray antiproton-to-proton flux ratio between 1 and 100 GeV is presented. The results were obtained with the PAMELA experiment, which was launched into low-earth orbit on-board the Resurs-DK1 satellite on June 15th 2006. PAMELA is equipped with a silicon-microstrip magnetic spectrometer and a silicon-tungsten imaging calorimeter and has been collecting data since July 2006. During 500 days of data collection a total of about 1000 antiprotons have been identified, including 100 above an energy of 20 GeV. The high-energy results are a ten-fold improvement in statistics with respect to all previously published data. The antiproton-to-proton flux ratio increases smoothly with energy up to about 10 GeV, in agreement with previous experiments, and then levels off. The data follow the trend expected from secondary production calculations and significantly constrain contributions from exotic sources, e.g. dark matter ...

2008-01-01

425

A conceptual design study of superconducting proton linac for Neutron Science Project. 1

A preliminary chemical characterization is presented of phosphate-free aminolipids isolation from Chlorobium limicola f. thiosulfatophilum. The lipid contains no phosphorus, glycerol, sugar, ornithine, or lysine. Ultraviolet absorption and fluorescence spectra indicate that the amino moiety of the lipid is an aromatic heterocyclic compound. Infrared spectra indicate that the lipid is a secondary or tertiary amide, and gas chromatograhic analysis of the hydrolyzed lipid shows that for each 1100 g of lipid, 1 mol of myristic acid (C/sub 14:0/) is linked in an amide bond. Acid hydrolysis of the lipid yields two fluorescent substances, A (ninhydrine positive) and B (negative), in addition to myristic acid. Proton nuclear magnetic resonance (NMR) studies indicate that substance A contains a butyl groups attached to a conjugated ring carbon, two equivalent ethyl groups attached to one or two nitrogen atoms, and two downfield protons (8.4 ppm), ...

1983-04-12

426

A DRAMATICALLY REDUCED SIZE IN THE GANTRY DESIGN FOR THE PROTON-CARBON THERAPY.

The Neutron Science Project at Japan Atomic Energy Research Institute has been proposed for the research of nuclear transmutation technology and the basic science with a spallation neutron source. The project calls for an 8MW proton linac which accelerates 5.3mA average current cw and pulsed beams up to 1.5GeV. The superconducting (SC) rf-cavity is the main option for the energy part from 100MeV to 1.5GeV because by using the SC structure, less power is consumed in cw operation than by using a normal conducting (NC) structure. A conceptual design study of the superconducting proton linac is reported. The SC linac is composed of 8 {beta} sections. Each section has the identical 5-cell cavities with the surface peak field of 16MV/m. The total number of cavities is 284, and the length of the SC linac is 690m. The lattice design is determined with the equipartitioned condition and the matched envelope equations for the minimum emittance growth. The ...

1998-09-01

427

A Compact Linac for Proton Therapy Based on a Dielectric Wall Accelerator

Gantries in the proton/carbon cancer therapy machines represent the major cost and are of the largest size. This report explains a new way to the gantry design. The size and cost of the gantries are reduced and their use is simplified by using the fixed magnetic field. The ''new'' gantry is made of a very large momentum acceptance non-scaling Fixed Field Alternating Gradient (FFAG) quarter and half arc beam lines. The gantry is made of combined function magnets with a very strong focusing and small dispersion function. Additional magnets with a fast response are required to allow adjustments of the beam position for different energies at the beginning of the gantry. Additional strong focusing magnets following the gantry have also to be adjustable to provide required spot size and radial scanning above the patients. The fixed field combined function magnets could be made of small permanent magnets for the ...

2006-06-23

428

Two years of flight of the Pamela experiment: results and perspectives

A novel compact CT-guided intensity modulated proton radiotherapy (IMPT) system is described. The system is being designed to deliver fast IMPT so that larger target volumes and motion management can be accomplished. The system will be ideal for large and complex target volumes in young patients. The basis of the design is the dielectric wall accelerator (DWA) system being developed at the Lawrence Livermore National Laboratory (LLNL). The DWA uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. High electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The system will produce individual pulses that can be varied in intensity, energy and spot width. The IMPT planning system will optimize delivery characteristics. The system will be capable of being sited in a conventional linac vault and provide intensity ...

2007-10-29

429

Twenty Years of Tevatron Operation

PAMELA is a satellite borne experiment designed to study with great accuracy cosmic rays of galactic, solar, and trapped nature in a wide energy range (protons: 80 MeV-700 GeV, electrons 50 MeV-400 GeV). Main objective is the study of the antimatter component: antiprotons (80 MeV-190 GeV), positrons (50 MeV-270 GeV) and search for antinuclei with a precision of the order of $10^{-8}$). The experiment, housed on board the Russian Resurs-DK1 satellite, was launched on June, $15^{th}$ 2006 in a $350\\times 600 km$ orbit with an inclination of 70 degrees. In this work we describe the scientific objectives and the performance of PAMELA in its first two years of operation. Data on protons of trapped, secondary and galactic nature - as well as measurements of the December $13^{th}$ 2006 Solar Particle Event - are also provided.

2008-01-01

430

The new Tevatron beam position monitor front-end software

The superconducting Tevatron accelerator at Fermi National Accelerator Laboratory (Fermilab) has surpassed twenty years of operation. The Tevatron is still the highest energy particle accelerator in the world and will remain so until the commissioning of the LHC in Europe later this decade. The Tevatron has operated in a Fixed Target mode, accelerating a proton beam into stationary targets/detectors, as well as a Colliding Beam mode, continuously colliding counter rotating beams of protons and antiprotons. Upon completion, the Tevatron cryogenic system became the world's largest helium refrigeration system. In 1993, the Tevatron cryogenic system was given the designation of International Historic Mechanical Engineering Landmark by the American Society of Mechanical Engineers. The operational history, experiences and statistics of the Tevatron, with an emphasis on the cryogenic system, is presented. Improvements, upgrades and current ...

2004-07-15

431

The isolation of "1"3"9Ce after production by a proton-induced nuclear reaction on praseodymium

The Tevatron is a proton anti-proton accelerator collider operating at the Fermi National Accelerator Laboratory. The machine is currently delivering beam for the CDF and D0 experiments, which expect increasing luminosity until the conclusion of Run II, planned for 2009. The Laboratory defined a plan for achieving higher luminosity, and one of the tasks is the upgrade of the accelerator's beam position monitor (BPM). The Tevatron was built during the early eighties and some of its control systems, including the BPMs, are still the original ones. This paper describes the front-end software of the Tevatron BPM upgrade, from the requirements to the implementation, and the underlying hardware setup. The front-end software designed is presented, emphasizing its modularity and reusability, allowing it to be applied to other Fermilab machines.

2005-05-01

432

Studies of the fundamental nature of catalytic acidity, sites, and intermediates: Progress report for period August 1, 1987-July 31, 1988

A method, based on anion exchange chromatography, is presented for the isolation of "1"3"9Ce after production by a proton-induced nuclear reaction on a thick praseodymium target. After bombardment the target is dissolved in nitric acid and "1"3"9Ce oxidised to the Ce(IV) oxidation state with bromic acid. "1"3"9Ce is then separated form the praseodymium by anion exchange chromatography on a Ag MP-1 resin column in a nitric acid - bromic acid mixture. "1"3"9Ce is sorbed onto the resin column and praseodymium eluted with the acid mixture. The bromic acid is washed out of the column with nitric acid and "1"3"9Ce finally eluted with dilute nitric acid containing sulphur dioxide.

2001-02-17

433

Spectroscopy of {sup 25}Al and {sup 26,27,28}P using high-energy stripping reactions

Neopentane, because of its unique structural features, was found to be a useful probe for the assay of the acidity of various zeolites. The C-C bond was attacked by catalyst protons yielding CH/sub 4/ and the isobutyl carbenium ion in equal quantities. The latter either decomposed to produce isobutene or underwent secondary reactions. New avenues for reaction were opened with isobutane. The reaction of the Bronsted protons with the tertiary CH bonds produced H/sub 2/ and the same isobutyl carbenium ion. Hydride ion transfer of the same tertiary hydrogen to existing carbenium ions also occurred and the results showed that about half of the reaction was carried by this pathway. As with Neopentane, the C-C bond could also be attacked yielding the sec-propyl carbenium ion. These tools are being further developed.

1988-06-01

434

Spectroscopy of "2"5Al and "2"6","2"7","2"8P using high-energy stripping reactions

We report here results of an application of single-nucleon stripping reactions at high energies (65 MeV/u) in inverse kinematics to obtain spectroscopic factors. From measurements of the partial cross-sections for ground and excited states in residual nuclei formed in one-proton stripping reactions, single particle orbits and occupancies of light nuclei have been studied in the s-d shell. Single proton stripping cross-sections of {sup 25}Al and {sup 26,27,28}P on a Be target have been measured using the S800 spectrograph and the NaI(Tl) array at the NSCL. These results indicate that this technique may provide a general tool for the intermediate energy range analogous to transfer (pick-up) reactions at low-energy.

1998-12-21

435

STATUS OF THE DIELECTRIC WALL ACCELERATOR

We report here results of an application of single-nucleon stripping reactions at high energies (65 MeV/u) in inverse kinematics to obtain spectroscopic factors. From measurements of the partial cross-sections for ground and excited states in residual nuclei formed in one-proton stripping reactions, single particle orbits and occupancies of light nuclei have been studied in the s-d shell. Single proton stripping cross-sections of "2"5Al and "2"6","2"7","2"8P on a Be target have been measured using the S800 spectrograph and the NaI(Tl) array at the NSCL. These results indicate that this technique may provide a general tool for the intermediate energy range analogous to transfer (pick-up) reactions at low-energy.

1998-12-21

436

Real-time configuration changes of the ATLAS High Level Trigger

The dielectric wall accelerator (DWA) system being developed at the Lawrence Livermore National Laboratory (LLNL) uses fast switched high voltage transmission lines to generate pulsed electric fields on the inside of a high gradient insulating (HGI) acceleration tube. High electric field gradients are achieved by the use of alternating insulators and conductors and short pulse times. The system is capable of accelerating any charge to mass ratio particle. Applications of high gradient proton and electron versions of this accelerator will be discussed. The status of the developmental new technologies that make the compact system possible will be reviewed. These include, high gradient vacuum insulators, solid dielectric materials, photoconductive switches and compact proton sources.

2009-04-22

437

Proton Form Factors measurements in the time-like region

The ATLAS High Level Trigger (HLT) is a distributed real-time software system that performs the final online selection of events produced during proton-proton collisions at the Large Hadron Collider (LHC). It is designed as a two-stage trigger and event filter running on a farm of commodity PC hardware. Currently the system consists of about 850 processing nodes and will be extended incrementally following the expected increase in luminosity of the LHC to about 2000 nodes. The event selection within the HLT applications is carried out by specialized reconstruction algorithms. The selection can be controlled via properties that are stored in a central database and are retrieved at the startup of the HLT processes, which then usually run continuously for many hours. To be able to respond to changes in the LHC beam conditions, it is essential that the algorithms can be re-configured without disrupting data taking while ensuring a consistent and reproducible ...

2010-01-01

438

Protective nitride formation on stainless steel alloys for proton exchange membrane fuel cell bipolar plates

I present an overview of the measurement of the proton form factors in the time-like regiun. BABAR has recently measured with great accuracy the e{sup +} e{sup -} {yields} p p-bar reaction from productiun threshold up to an energy of {approx} 4.5 GeV; finding evidence for a ratio of the electric to magnetic form factur greater than unity, contrary to expectation. In agreement with previous measurements. BABAR confirmed the steep rise uf the magnetic form factor close to the p p-bar mass threshold, suggesting the possible presence of an under-threshuld N N-bar vector state. These and uther open questiuns related to the nucleon furm factors both in the time-like and space-like region, wait for more data with different experimental techniques to be possibly solved.

2007-05-15

439

British Library Electronic Table of Contents (United Kingdom)

Gas nitridation has shown excellent promise to form dense, electrically conductive and corrosion-resistant Cr-nitride surface layers on Ni-Cr base alloys for use as proton exchange membrane fuel cell (PEMFC) bipolar plates. Due to the high cost of nickel, Fe-base bipolar plate alloys are needed to meet the cost targets for many PEMFC applications. Unfortunately, nitridation of Fe-base stainless steel alloys typically leads to internal Cr-nitride precipitation rather than the desired protective surface nitride layer formation, due to the high permeability of nitrogen in these alloys. This paper reports the finding that it is possible to form a continuous, protective Cr-nitride (CrN and Cr2N) surface layer through nitridation of Fe-base stainless steel alloys. The key to form a protective Cr...

2007-01-01

440

Production of radioisotopes in the ORNL 86-inch cyclotron

Predicting the proton conductivity of perfluorosulfonic acid membrane via combining statistical thermodynamics and molecular dynamics simulation

The radioisotope production facilities and programs of the 86-Inch Cyclotron are reviewed in this presentation. The 86-Inch Cyclotron is designed to accelerate protons to a maximum energy of 22 MeV for internal targets. These protons are used to bombard metals that are electroplated, potted or soldered to water-cooled plates. Additionally, metals and inorganic compounds are bombarded in water-cooled tube targets. High radioisotope production rates are obtained by beam currents as large as 3 mA. Production rates for /sup 11/C, /sup 57/Co, /sup 67/Ga, /sup 68/Ge, /sup 109/Cd, and other isotopes are presented. The production of /sup 11/C for the carboxyl labeling of amino acids in cooperation with Oak Ridge Associated Universities is discussed. The 86-Inch Cyclotron is used for those programs requiring a larger beam current than is available from commercial cyclotrons.

1981-04-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

441

British Library Electronic Table of Contents (United Kingdom)

Abstract The electrochemical properties of a perfluorosulfonic acid (PFSA) membrane are estimated using a combination of molecular dynamics simulation and statistical thermodynamic model. We obtain all parameters in an ionic conductivity model from an atomistic simulation and remove all adjusted model parameters. From a microscopic point of view, the hydrated PFSA membrane shows micro-phase segregation which separated into hydrophilic and hydrophobic phases. Our present work originates with this phenomenon and we treat this phase segregation as if it is a continuous phase for each of which the proton (H+) is transported inside the PFSA membrane/solvent (water and alcohols) mixture. The chemical potential for a given system is estimated using a molecular simulation technique to predict the ...

2011-01-01

442

Polyamide/Polystyrene Blend Compatibilisation by Montmorillonite Nanoclay and its Effect on Macroporosity of Gas Diffusion Layers for Proton Exchange Membrane Fuel Cells

British Library Electronic Table of Contents (United Kingdom)

This work deals with a new route to modify polymer blend morphology in order to improve the porosity of gas diffusion layers (GDLs) for proton exchange membrane fuel cells (PEMFCs). First, electrically conductive polymer-based blends were carefully formulated using a twin-screw extrusion process. Blend electrical conductivity was ensured by the addition of high specific surface area carbon black and synthetic graphite flakes. Final GDL porosity, in particular its macroporosity, was generated by melt blending polyamide 11 (PA11) matrix with polystyrene (PS) followed by PS extraction with tetrahydrofuran (THF) solvent at room temperature. In order to improve GDL porosity by the optimisation of PS dispersion in the PA11 matrix, PA11/PS blends were compatibilised by the addition of 2 wt.-% of ...

2007-01-01

443

Particle and X-ray damage in pn-CCDs

Partial wave expansion of ion-atom elastic scattering in solids

The fully depleted pn-junction charge coupled device (pn-CCD) has been developed as a detector for X-ray imaging and high-resolution spectroscopy for the X-ray satellite missions XMM and ABRIXAS. If the detector is exposed to a particle radiation environment, the energy resolution is degraded due to charge transfer losses and a dark current increase. In a first experiment, prototype devices were irradiated with 10 MeV protons. After completion of the detector development, the proton irradiation was repeated for a quantitative study of the radiation damage, relevant for the satellite missions. The irradiation test was extended by a 5.5 MeV {alpha}-particle and a 6 keV X-ray exposure of the pn-CCD, including the CAMEX preamplifier chip.

2000-01-11

444

New pulse sequence for simultaneous T1, T2, and RHO determination in whole-body proton MR imaging

Elastic scattering cross sections of keV protons in solids (Z=3-82) are calculated using the partial wave expansion technique and the ''muffin-tin'' bound-atom potential. The differential cross sections for small scattering angles of less than 10deg are smaller than those with the Ziegler-Biersack-Littmark potential at all energies and for all solids, although, for larger angles, the two cross sections agree with each other. The mean free paths of the protons in the solids, obtained from the total cross sections, decrease very slowly with decreasing energy. Furthermore, at low energies they approach half the nearest-neighbor distance, which is taken as the radius of the augmented plane wave sphere in the muffin-tin model of crystalline solids. (orig.).

445

Neutron inelastic scattering to octupole states in single-closed-shell nuclei

A newly developed method to support tissue characterization in routine MR imaging is presented. It represents a compromise between the practical requirements of clinical routine (short measurement time, multisection imaging) and the necessary accuracy of the relaxation parameter evaluation. The sequence employed is a modification of the PHAPS technique and works with two excitation pulses. It allows the simultaneous acquisition of all measurement data for the subsequent T1, T2, and rho evaluations. T1 is determined with a specially designed computation formula based on four signal ratios. A multiexponential T2 analysis is performed with use of 28 echoes. From these parameters, relative proton density can be computed.

446

Muon physics with the proposed Pulsed Lepton Source at LAMPF

Differential cross sections for the excitation of the first octupole-vibrational state in the closed-neutron-shell nuclides "8"8Sr and "9"0Zr and in the closed-proton shell-nuclei sup(116,118,120,124)Sn by 11 MeV neutrons are presented. The distorted-wave Born approximation is used to obtain deformation lengths, delta(3"-) for each state. Results are compared with earlier measurements of inelastic proton scattering to the same states. Although limited resolution in the neutron time-of-flight spectrometer complicates the interpretation of the Sn data, the overall conclusion that deltasub(nn')(3"-) approx. deltasub(pp')(3"-) is supported by all of the measurements. (orig.).

447

Modulation of proton NMR free induction decay by spin diffusion

The Pulsed Lepton Source (PLS) project opens some exciting possibilities for muon and neutrino physics . The PLS would use the 0.25 4s proton pulses from the upgraded Proton Storage Ring (PSR) at LAMPF to create short, intense bursts of muons and neutrinos. The neutrino beam would be used for a few fundamentally important weak interaction physics experiments. The muon beams would find a wide variety of applications in both fundamental and applied'' muon physics areas. After a brief discussion of the physical layouts of the PSR and the proposed PLS in Sec. 2 and muon area in Sec. 3, we note some of the muon physics experiments and areas that could advantageously be addressed at the PLS in Secs. 4 and 5, and conclude in Sec. 6.

1992-01-01

448

Modeling of an Inductive Adder Kicker Pulser for a Proton Radiography System

The effects of spin diffusion on the free induction decay (FID) of protons associated with the noncrystalline domains of two polymers, polyethylene and blended Nylon 66 (ZYTEL-408), have been examined using Goldman--Shen NMR pulse sequence ((1/2)..pi..x-t/sub 0/-(1/2)..pi..x-bar-tau-(1/2)..pi..x-t). At tau< or approx. =100 ..mu..s, the FID is drastically distorted from the exponential form while at longer tau(tau> or approx. =500 ..mu..s) an exponential FID is observed; but its transverse spin relaxation rate is smaller than that of the FID obtained after a single (1/2)..pi..x pulse and approaches this value at the limit of large tau. These findings are interpreted in terms of the theory of rapid spin diffusion. The spatial variation in the spin relaxation rate within the noncrystalline domain is inferred.

1982-02-01

449

Measurements of vibrational excitation of N_2, CO, and NO by low energy proton impact

An all solid-state kicker pulser for a proton radiography system has been designed. Multiple solid-state modulators stacked in an inductive-adder configuration are utilized in this kicker pulser design. Each modulator is comprised of multiple metal-oxide-semiconductor field-effect transistors (MOSFETs) which quickly switch the energy storage capacitors across a magnetic induction core. Metglas is used as the core material to minimize loss. Voltage from each modulator is inductively added by a voltage summing stalk. A circuit model of a prototype inductive adder kicker pulser modulator has been developed to predict the performance of the pulser modulator. The modeling results are compared with experimental data.

2001-06-12

450

Measurement of the total photoabsorption cross section on a proton in the energy range 600?1500 MeV at the GRAAL

Differential scattering experiments are reported for proton impact on N_2, CO, and NO in the energy range E/sub lab/=30--80 eV. The measurements include the range of very small scattering angles around 0"0 as well as the rainbow region. The vibrationally resolved energy-loss spectra show a relatively low vibrational inelasticity for all three systems. Differential cross sections, transition probabilities, and the mean vibrational energy transfer are presented. Rotational excitation is indicated by the broadening of the energy-loss peaks which is most significant for H"+--NO. The small-angle scattering data for vibrational excitation in CO show good agreement with the impact parameter theory using the known long-range interactions for this system.

1979-07-01

451

British Library Electronic Table of Contents (United Kingdom)

The total photoabsorption cross section on a free proton was measured at the GRAAL facility in the energy range E ? = 600?1500 MeV. The large-aperture LAGRAN?E detector and a liquid hydrogen target were used in the experiment performed with a back-scattered Compton gamma beam. To improve the accuracy, two alternative methods were employed. First, a subtraction method of using empty-target measurements allowed the cross section ? tot to be evaluated directly because of a low level of the electromagnetic background. Second, an algorithm for evaluating ? tot on the basis of summing the dominating partial cross sections was developed. Experimental results obtained for ? tot by the two methods are compared with existing data.

2008-01-01

452

Measurement of the photon-proton total cross section at a center-of-mass energy of 209 GeV at HERA

Matching of water and temperature fields in proton exchange membrane fuel cells with non-uniform distributions

The photon-proton total cross section has been measured in the process e{sup +}p{yields}e{sup +}{gamma}p{yields}e{sup +}X with the ZEUS detector at HERA. Events were collected with photon virtuality Q{sup 2}<0.02 GeV{sup 2} and average {gamma}p center-of-mass energy W{sub {gamma}}{sub p}=209 GeV in a dedicated run, designed to control systematic effects, with an integrated luminosity of 49 nb{sup -1}. The measured total cross section is {sigma}{sub tot}{sup {gamma}}{sup p}=174{+-}1 (stat.){+-}13 (syst.) {mu}b. The energy dependence of the cross section is compatible with parameterizations of high-energy pp and pp-bar data.

2002-04-15

453

British Library Electronic Table of Contents (United Kingdom)

In this work, a three-dimensional multiphase non-isothermal model incorporated with a capillary-extended sub-model in gas channels is used to investigate the coupled phenomena of water and thermal transport in proton exchange membrane fuel cells. Distributions of water and temperature along the flow path in the channel are highlighted and the pros and cons of various operating temperatures are elaborated. In addition, this work also sheds light on the impacts of temperature variations of bipolar plates induced by non-uniform cooling conditions, which have been overlooked by most previous works. An important phenomenon of water distribution, dry-out at inlets and flooding at outlets (DIFO), is observed and this non-uniform distribution is revealed to be greatly influenced by the operating t...

2011-01-01

454

Ion-induced M X-ray emission from heavy lanthanides

Extracting Nucleon Strange and Anapole Form Factors from World Data

Thick targets of several heavy lanthanide (Ho-Lu) compounds were bombarded by protons and "3He ions of 3 MeV/amu, and M_#alpha# and M_#beta# X-rays were measured with a crystal spectrometer. Ionization probabilities of the N-shell for zero impact parameter were obtained from the X-ray intensity ratio for proton and "3He ion impacts. A shell dependence of the ionization probability was found in a scaling plot. X-ray spectra of lanthanide compounds were compared and no chemical effect was observed. This result is considered to be due to the fact that the main component of M_#alpha# and M_#beta# lines is for radiative transition after the refilling of the 4f orbit (3d"-"14f"n"+"1 #-># 4f"n) where n denotes the number of 4f electrons of the target atom before ionization. (orig.).

1987-12-01

455

Extension of energy acceptance of Bragg curve counter at the high-energy end

The complete world set of parity-violating electron scattering data up to Q{sup 2}{approx}0.3 GeV{sup 2} is analyzed. We extract the current experimental determination of the strange electric and magnetic form factors of the proton, as well as the weak axial form factors of the proton and neutron, at Q{sup 2}=0.1 GeV{sup 2}. Within experimental uncertainties, we find that the strange form factors are consistent with zero, as are the anapole contributions to the axial form factors. Nevertheless, the correlation between the strange and anapole contributions suggest that there is only a small probability that these form factors all vanish simultaneously.

2006-09-08

456

We have developed an energy-extension method of a Bragg curve counter (BCC) at the high-energy end for the measurements of double-differential cross-sections (DDXs) of fragment productions induced by tens of MeV protons. In this method, we estimate the incident energies of the fragments penetrating a BCC on the basis of the energy loss and atomic number (Z). We applied this method to the DDX measurements of the {sup nat}C(p, Li) and {sup nat}C(p, Be) reactions induced by 70 MeV protons. The validity of this method has been confirmed by comparing the DDXs of beryllium with theoretical predictions of the PHITS code and the two-body kinematics. This method improves the energy acceptance of the BCC for light fragments twice as wide as that of a conventional method without remodeling of the BCC and any loss of the original advantages.

2008-07-11

457

Explosives detector

Exclusive ?0 electroproduction on transversely polarized protons

An apparatus for non-invasively inspecting an object, such as an item of luggage, for explosives material is described. It comprises a multi-channel thermal neutron inspection system having a plurality of neutron irradiation chambers. Simultaneous operation of several channels increases the maximum system throughput several times. Each chamber has a lithium neutron source which is stimulated to neutron production by a proton beam. Beam switching magnets are energised by pulsing to divert a common proton beam to each source in turn. The initial beam is generated by a radio frequency quadrupole accelerator. The advantages of this system are very low residual source activity and controllable neutron production thereby minimising safety hazards. The irradiation chamber may contain several different gamma ray detectors to identify the elements present in explosives material. In addition, a neutron radiography imaging means may be employed to ...

1991-10-02

458

Excitation of ''M1 transitions'' in inelastic proton scattering

The exclusive electroproduction of ?0 mesons was studied with the HERMES spectrometer at the DESY laboratory by scattering 27.6 GeV positron and electron beams off a transversely polarized hydrogen target. Spin density matrix elements for this process were determined from the measured production- and decay-angle distributions of the produced ?0 mesons. These matrix elements embody information on helicity transfer and the validity of s-channel helicity conservation in the case of a transversely polarized target. From the spin density matrix elements, the leading-twist term in the single-spin asymmetry was calculated separately for longitudinally and transversely polarized ?0 mesons. Neglecting s-channel helicity changing matrix elements, results for the former can be compared to calculations based on generalized parton distributions, which are sensitive to the contribution of the total angular momentum of the quarks to the proton spin.

2009-08-17

459

Estimation of essential and trace elements in some medicinal plants by PIXE and PIGE techniques

The high selectivity of 201 MeV inelastic proton scattering at forward angles for exciting ..delta..L=0 spin flip transitions is outlined by comparison with (e,e') and 65 MeV (p,p') measurements. A summary of the results obtained on the calcium isotopes, the N=28 isotones, /sup 88/Sr and /sup 90/Zr is presented. The differences in the relative M1 strength distributions between the (p,p') and the (e,e') results are discussed. Preliminary results on /sup 208/Pb are given; the ''isoscalar'' 1/sup +/ state at 5.846 MeV is excited.

1984-03-01

460

Electrochemistry Modeling of Proton Exchange Membrane (PEM) Water Electrolysis for Hydrogen Production

Proton induced X-ray emission (PIXE) and proton induced {gamma}-ray emission (PIGE) techniques are employed for the determination of essential and trace elements in some commonly used medicinal plants of north east India. Light elements such as Na, Mg, Al and P are determined by PIGE while medium Z elements such as K, Ca, Mn, Fe, Cu, Zn, Rb and Sr are determined by PIXE. Analysis is performed on pellets (thick targets) prepared using powders of the specimens which, in turn, are obtained following a series of processing steps. Plant based biological certified reference materials (CRMs) served as standards for quantification. These elements are found to be present in varying concentrations in the studied plants, with the contents of Mn and Zn being notably large in certain specimens. Medicinal properties possessed by these plants have been correlated with their elemental distribution.

2008-04-15

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

461

ELECTROMAGNETIC AND THERMAL SIMULATIONS FOR THE SWITCH REGION OF A COMPACT PROTON ACCELERATOR

An electrochemistry model was developed to analyse the J-V characteristics of a Proton Exchange Membrane (PEM) water electrolyzer for hydrogen production. The Butler-Volmer equation and water transport characteristics through electrolyte membrane were employed to simulate the electrode activation over-potential and membrane ohmic over-potential, respectively. The modeling results are found to agree reasonably well with experimental data published in the literature. The parametric simulations show that the ohmic over-potential is relatively small with typical water content in the membrane. Compared with the cathode over-potential, the anode over-potential is more significant and constitutes the major source of voltage loss. The high anode over-potential is due to the relatively slow oxidation kinetics, which is related to anode material property and microstructure. This model can be integrated with a photovoltaic or wind turbine model to predict the performance of ...

2006-06-13

462

Conductivity studies on commercially available proton-conducting membranes with different equivalent weight

A compact proton accelerator for medical applications is being developed at Lawrence Livermore National Laboratory. The accelerator architecture is based on the dielectric wall accelerator (DWA) concept. One critical area to consider is the switch region. Electric field simulations and thermal calculations of the switch area were performed to help determine the operating limits of rmed SiC switches. Different geometries were considered for the field simulation including the shape of the thin Indium solder meniscus between the electrodes and SiC. Electric field simulations were also utilized to demonstrate how the field stress could be reduced. Both transient and steady steady-state thermal simulations were analyzed to find the average power capability of the switches.

2007-06-15

463

Complexation of vanadium (v) with alanine in different ionic strength

Two perfluorosulfonic acid membranes, Nafion{sup R} 105 and Nafion{sup R} 115 with the same thickness but different equivalent weights (EW = 1000 g/eq. resp. 1100 g/eq.) were characterised by conductivity measurements at different water vapour activities in the temperature range of 25-70{sup o}C. The results demonstrate that a lower membrane equivalent weight opens the possibility to obtain the needed proton conductivity at lower water vapour activity. This is especially important for those fuel cell applications, in which the cell is operated without external humidification of the fuel gases. (author) 5 figs., 5 refs.

1999-08-01

464

Comparison of energy flows in deep inelastic scattering events with and without a large rapidity gap

The formation constants of species formed in the system H"+"+alanine and VO_"2"+alanine have be determined in aqueous solution for 1.0protonation constant of the amino group of alanine has been determined using a computer program which employ a least-squares method. The defence of the protonation of alanine and the stability constant of the species on ionic strength are described by a Debby-huckel type equation.

2002-04-10

465

COSY synchrotron and storage ring for medium energy physics

Energy flows in deep inelastic electron-proton scattering are investigated at a centre-of-mass energy of 296 GeV for the range Q{sup 2}{>=}10 GeV{sup 2} using the ZEUS detector. A comparison is made between events with and without a large rapidity gap between the hadronic system and the proton direction. The energy flows, corrected for detector acceptance and resolution, are shown for these two classes of events in both the HERA laboratory frame and the Breit frame. From the differences in the shapes of these energy flows we conclude that QCD radiation is suppressed in the large-rapidity-gap events compared to the events without a large rapidity gap. (orig.)

1994-07-01

466

Atmospheric proton and deuterium energy spectra determination with the MASS2 experiment

At present the cooler synchrotron COSY a synchrotron and storage ring for medium energy physics is being commissioned at Juelich. The construction of the ring was finished during September 1992. The cooler ring will deliver protons in the momentum range from 270 to 3300 MeV/c. The phase density of the circulating protons will be increased with electron cooling at injection and with stochastic cooling at momenta between 1500 and 3300 MeV/c. High luminosity internal experiments as well as high resolution external experiments will be possible. Details of the lattice, to match the different ion optical requirements for cooling, acceleration, internal experiments and ultra-slow extraction will be discussed. An overview of the performance of the ion sources, the injector cyclotron, the ring, the injection beamline are given. The realization status of the extraction beamlines to the external experimental area is given. The experience on the ...

1993-01-01

467

Antimatter production in supernova remnants

The energy spectra of atmospheric-secondary protons and deuterium nuclei have been measured during the September 23, 1991, balloon flight of the NMSU/Wizard - MASS2 instrument. The apparatus was launched from Fort Sumner, New Mexico. The geomagnetic cutoff at the launch site is about 4.5 GV/c. The instrument was flown for 9.8 hours at an altitude of over 100,000 feet. Particles detected below the geomagnetic cutoff have been produced mainly by the interactions of the primary cosmic rays with the atmosphere. The measurement of cosmic ray energy spectra below the geomagnetic cutoff provide direct insights into the particle production mechanism and allows comparison to atmospheric cascade calculations.

1995-09-01

468

A non-resonant RF cavity loaded with amorphous alloy for proton cancer therapy

We calculate the energy spectra of cosmic rays (CR) and their secondaries produced in a supernova remnant (SNR), taking into account the time-dependence of the SNR shock. We model the trajectories of charged particles as a random walk with a prescribed diffusion coefficient, accelerating the particles at each shock crossing. Secondary production by CRs colliding with gas is included as a Monte Carlo process. We find that SNRs produce less antimatter than suggested previously: The positron/electron ratio and the antiproton/proton ratio are a few percent and few $\\times 10^{-5}$, respectively. Moreover, the obtained positron/electron ratio decreases with energy, while the antiproton/proton ratio rises at most by a factor of two above 10 GeV.

2011-01-01

469

A new artificial bee swarm algorithm for optimization of proton exchange membrane fuel cell model parameters

A non-resonant RF cavity loaded with amorphous alloy cores has been designed and tested. The cavity has a re-entrant structure loaded with 8 amorphous alloy toroidal core and its characteristic impedance is designed as 450 Omega . The RF power is fed by 1 kW solid state amplifier using a step-up transformer with 1:9 impedance ratio. In the high power test, an accelerating gap voltage of more than 900 V was measured with input power of 1 kW in the frequency range of 1 to 10 MHz. The voltage standing wave ratio (VSWR) was less than 2.0. The results prove that the cavity may be used successfully within a compact proton synchrotron for a cancer therapy facility. (3 refs).

1999-01-01

470

British Library Electronic Table of Contents (United Kingdom)

An appropriate mathematical model can help researchers to simulate, evaluate, and control a proton exchange membrane fuel cell (PEMFC) stack system. Because a PEMFC is a nonlinear and strongly coupled system, many assumptions and approximations are considered during modeling. Therefore, some differences are found between model results and the real performance of PEMFCs. To increase the precision of the models so that they can describe better the actual performance, optimization of PEMFC model parameters is essential. In this paper, an artificial bee swarm optimization algorithm, called ABSO, is proposed for optimizing the parameters of a steady-state PEMFC stack model suitable for electrical engineering applications. For studying the usefulness of the proposed algorithm, ABSO-based results...

2011-01-01

471

A measurement of the parity-violating gamma-ray asymmetry in the neutron-proton capture

A He-gas Cooled, Stationary Granular Target

The {rvec n} + p {yields} d + {gamma} experiment under construction at LANSCE studies the weak interaction between neutrons and protons. The experiments will measure the directional dependence of the parity-violating {gamma}-ray asymmetry, A{sub {gamma}}, in the polarized cold neutron capture by para-hydrogen. The goal is to measure A{sub {gamma}} with uncertainty of 0.5 x 10{sup -8}, 10% of its predicted value. A{sub {gamma}} primarily isolates the {Delta}I = 1 component of the hadronic weak interaction and thus will determine the long-range weak pion-nucleon coupling constant H{sub {pi}}{sup 1}. The experiment is carefully designed for the LANSCE pulsed spallation neutron source to achieve the proposed statistical precision and to control systematic errors. We discuss the experiment and its status.

2002-01-01

472

2007 2008 ACADEMIC TRAINING PROGRAMME

In the CERN approach to the design of a neutrino factory, the repetition frequency of the proton beam is high enough to consider stationary solid targets as a viable solution for multi-MW beams. The target consists of high density tantalum spheres of 2 mm diameter which can efficiently be cooled by passing a high mass flow He-gas stream through the voids between the Ta-granules. Very small thermal shocks and stresses will arise in this fine grained structure due to the relatively long burst of 3.3 ms from the SPL-proton linac. In a quadruple target system where each target receives only one quarter of the total beam power of 4 MW, conservative temperature levels and adequate lifetimes of the target are estimated in its very high radiation environment. A conceptual design of the integration of the target into the magnetic horn-pion-collector is presented.

2003-01-01

473

CERN Multimedia

LECTURE SERIES 14, 15, 17 January 2008 11:00 to 12:00 - Council Chamber, bldg. 503-1-001 Applications of accelerators to tumour therapy U. AMALDI, TERA Foundation & University of Milano Bicocca The first lecture is devoted to an historical review of the developments of the teletherapy techniques which make use of hadron beams and are collectively called "hadrontherapy". The main emphasis is on the use of protons and light ions, but also neutrons, pions and antiprotons are considered. The second lecture reviews the rationale behind the use of carbon ions in the treatment of radioresistant tumours and the results obtained both with proton and carbon ion beams on the 60 000 patients treated worldwide. The numbers of patients who would profit from hadrontherapy are presented together with the current landscape of running and planned hospital based centres. The main technical challenges set by this therapeutic modality are discussed in the ...

2007-01-01

474

The role of surfactant in synthesis of magnetic nanocrystalline powder of NiFe2O4 by sol-gel auto-combustion method

British Library Electronic Table of Contents (United Kingdom)

In this work, a new sol-gel auto-combustion method has been performed to synthesize single phase nickel ferrite nanocrystalline powders by using n-cetyltrimethylammonium bromide, as a cationic surfactant. The gels were prepared from ferric and nickel nitrates and citric acid. Ammonia was used as pH adjusting agent as well. The effects of the surfactant on the after combustion calcination process and the reduction of the resulting powder crystallite size which affects the magnetic properties of the material were investigated by XRD and DTA/TGA techniques. The results showed that the ignition of the gels in air have a self-propagating behavior. Addition of surfactant to the starting solution affected the crystallite size of the synthesized powders and their phase constitution. The crystallit...

2008-01-01

475

The preparation of polyurethane foam combined with pH-sensitive alginate/bentonite hydrogel for wound dressings

British Library Electronic Table of Contents (United Kingdom)

Polyurethane (PU) foam was combined with protein drug-loaded pH-sensitive alginate-bentonite hydrogel for wound dressings. Alginate is a linear copolymer composed of 1?4-linked ?-D-mannuronic acid (M) and its c-5-epimer ?-Lguluronic acid (G). The amount of (M) and (G) and their sequential distribution are varied depending on the alginate source. Soluble sodium alginate can become a hydrogel when cross-linked with divalent cations and has widespread applications in the food, drink, pharmaceutical and bioengineering industries. Recently, it has been also proposed as a biomaterial for drug delivery systems. Bentonites are the natural inorganic polymers consisting of a large proportion of expandable clay minerals with a three-layer structure such as montmorillonite, beidellite, nontronite, etc...

2011-01-01

476

The effects of counter cation on lithium ion conductivity: In the case of the perovskite-type titanium oxides of La2/3?x Li3xTiO3 and LaTiO3

British Library Electronic Table of Contents (United Kingdom)

We performed hybrid-DFT calculations for La2/3?xLi3xTiO3 (LLT) with lithium ion conductivity, in order to investigate the detailed lithium ion conductive mechanism from the viewpoint of molecular orbital (MO) method. It was concluded that the very ionic lithium ion in bottleneck accelerates the lithium ion conduction. The calculated MO shows no chemical bonding between lithium ion and other ions. In comparison with the perovskite-type trivalent titanium oxide of LaTiO3, the effect of the titanium's reduction was also investigated. We showed the possibility of the high lithium conductivity in LaTiO3.

2009-01-01

477

Silica Polyamine Composites: New Supramolecular Materials for Cation and Anion Recovery and Remediation

British Library Electronic Table of Contents (United Kingdom)

Summary: The surface coverage of amorphous silica gels used in the synthesis of silica polyamine composites has been investigated by 29Si NMR. By diluting the polyamine anchor silane, chloropropyl trichlorosilane, with methyl trichlorosilane it was found that surface coverage could be markedly improved for a range of amine polymers after grafting to the silica surface. The commensurate decrease in the number of anchor points and increase in the number of free amines results in an increase in metal capacity and/or an improvement in capture kinetics. Solid state CPMAS-13C NMR has been employed to investigate the structure and metal ion binding of a series of these composite materials. It is reported that the highly branched polymer, poly(ethyleneimine) (PEI) exhibits much broader 13C NMR res...

2006-01-01

478

Separation of rubidium from irradiated aluminum-encapsulated uranium

Separation of rubidium from irradiated aluminum-encapsulated uranium

A procedure was developed for separating rubidium from irradiated aluminum encapsulated uranium. The separations procedure produces a final ultra-high purity RbCl product for subsequent high performance mass spectrometric analysis. The procedure involves first removing most of the macro-components and fission products by strong base anion exchange using, first, concentrated HCl, then oxalic acid media and second, selectively separating rubidium from alkaline-earth ions and other alkali-metal ions, including cesium, using Bio-Rex-40 cation-exchange resin. The resultant RbCl is then put through a final vacuum sublimation step. Ultra-pure reagents and specially clean glassware are used throughout the procedure to minimize contamination by naturally-occurring rubidium.

1993-05-01

479

Role of cetyltrimethylammonium bromide (cationic surfactant) on the tryptophan-MnO4- reaction

A procedure was developed for separating rubidium from irradiated aluminum encapsulated uranium. The separations procedure produces a final ultra-high purity RbCl product for subsequent high performance mass spectrometric analysis. The procedure involves first removing most of the macro-components and fission products by strong base anion exchange using, first, concentrated HCl, then oxalic acid media and second, selectively separating rubidium from alkaline-earth ions and other alkali-metal ions, including cesium, using Bio-Rex-40 cation-exchange resin. The resultant RbCl is then put through a final vacuum sublimation step. Ultra-pure reagents and specially clean glassware are used throughout the procedure to minimize contamination by naturally-occurring rubidium.

1982-01-01

480

British Library Electronic Table of Contents (United Kingdom)

Upon addition of permanganate to a solution of tryptophan (Trp), yellow-brown color species appears within the time of mixing of tryptophan in absence and presence of cetyltrimethylammonium bromide (CTAB), which was stable for some days. Spectroscopic and kinetic evidences suggest the formation of water-soluble colloidal MnO2 as the most stable reduction product of MnO4-. Carbon dioxide and ammonia are not formed as the oxidation products. Carbon-carbon double bond of indole moiety of Trp is responsible for the fast reduction of permanganate. Cetyltrimethylammonium bromide catalyses the permanganate oxidation of Trp with a rate enhancement of ca. 200-fold. Sub- and postmicellar catalytic effect of CTAB ascribed to the association/incorporation/solubilization of both reactants (MnO4- and Tr...

2009-01-01

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25

481

Neutron powder diffraction and solid-state deuterium NMR studies of Ca{sub 2}RuD{sub 6} and the stability of transition metal hexahydride salts

Neutron powder diffraction and solid-state deuterium NMR studies of Ca2RuD6 and the stability of transition metal hexahydride salts

The crystal structure of Ca{sub 2}RuD{sub 6} has been determined by neutron powder diffraction: space group Fm3m, K{sub 2}PtCl{sub 6} structure, as found for other hexahydride salts of group 8 metals with alkaline earth or lanthanide counter ions. No structural phase transition was observed between 340 K and 50 K. The deuterium nuclear quadrupole coupling constant, 54.7 kHz, leads to an ionic character of the Ru-D bond of 76%. The known trends in the behaviour of A{sub 2}MH{sub 6} salts are interpreted in terms of the ionization energies of the cation and the central metal atom.

2008-07-28

482

British Library Electronic Table of Contents (United Kingdom)

The crystal structure of Ca2RuD6 has been determined by neutron powder diffraction: space group Fm3m, K2PtCl6 structure, as found for other hexahydride salts of group 8 metals with alkaline earth or lanthanide counter ions. No structural phase transition was observed between 340K and 50K. The deuterium nuclear quadrupole coupling constant, 54.7kHz, leads to an ionic character of the Ru-D bond of 76%. The known trends in the behaviour of A2MH6 salts are interpreted in terms of the ionization energies of the cation and the central metal atom.

2008-01-01

483

Microemulsion-mediated synthesis of cobalt (pure fcc and hexagonal phases) and cobalt-nickel alloy nanoparticles

British Library Electronic Table of Contents (United Kingdom)

By choosing appropriate microemulsion systems, hexagonal cobalt (Co) and cobalt-nickel (1:1) alloy nanoparticles have been obtained with cetyltrimethylammonium bromide as a cationic surfactant at 500degreeC. This method thus stabilizes the hcp cobalt even at sizes (<10nm) at which normally fcc cobalt is predicted to be stable. On annealing the hcp cobalt nanoparticles in H2 at 700degreeC we could transform them to fcc cobalt nanoparticles. Microscopy studies show the formation of spherical nanoparticles of hexagonal and cubic forms of cobalt and Co-Ni (1:1) alloy nanoparticles with the average size of 4, 8 and 20nm, respectively. Electrochemical studies show that the catalytic property towards oxygen evolution is dependent on the applied voltage. At low voltage (less than 0.65V) the Co (he...

2009-01-01

484

Mechanism of solubilization in detergent solutions

Layer-by-layer assembly of thin film oxygen barrier

The kinetics of the solubilization of lauric acid, palmitic acid, stearic acid, and monopalmitin have been studied in detergent solutions as a function of concentration, temperature, and fluid flow. The detergents used were sodium dodecyl sulfate (an anionic surfactant), decyltrimethylammonium bromide (a cationic surfactant), sodium taurocholate (a trihydroxy bile salt), sodium taurodeoxycholate (a dihydroxy bile salt), and triton X-100 (a nonionic surfactant). At low temperature, solubilization can be described by a five-step mechanism is which micelle desorption and diffusion are rate controlling. At temperatures above the fatty acid penetration temperature, solubilization is governed by formation of a liquid crystalline phase at the fatty acid-detergent solution interface.

1981-11-01

485

Injection control and thermally stimulated current in ionic polarized polymer based light emitting diode

Thin films of sodium montmorillonite clay and cationic polyacrylamide were grown on a polyethylene terephthalate film using layer-by-layer assembly. After 30 clay-polymer layers are deposited, with a thickness of 571 nm, the resulting transparent film has an oxygen transmission rate (OTR) below the detection limit of commercial instrumentation (< 0.005 cc/m{sup 2}/day/atm). This low OTR, which is unprecedented for a clay-filled polymer composite, is believed to be due to a brick wall nanostructure comprised of completely exfoliated clay in polymeric mortar. With an optical transparency greater than 90% and potential for microwaveability, this thin composite is a good candidate for foil replacement in food packaging and may also be useful for flexible electronics packaging.

2008-06-02

486

Immobilization of bacteria in microgel grafted onto macroporous polyethylene

An effective method of enhancing charge injection and electroluminescence efficiency of polymer-based light emitting diode is introduced. Spin-coated films of poly (N-vinylcarbazole) blended with electron-transport material (Bu-PBD), laser dye (Coumarin6), and the typical supporting electrolyte (tetraethylammonium perchlorate; TEAP) were examined and it was found that the injection current and luminance of the light emitting diode doped with TEAP were enhanced dramatically after heat-treatment at 80 deg. C and appropriate biasing in an external electric field of 1.5x10"8 V/m at this temperature. The thermally stimulated current (TSC) was also measured to investigate the relaxation process of ionic space charges in the films. The relaxation times of ionic polarization were found to be related to the cation size of the electrolyte. And the relaxation time becomes long enough by the use of TEAP doping.

2003-08-22

487

FB-Line resin testing final report

The development of 'Green Chemistry' requires new materials to replace the conventional organic chemistry by biological catalysts, to produce fine chemicals in an environmentally friendly manner. Microbial whole cells can be directly used as biocatalysts, providing a simple and cheap methodology since enzyme isolation and purification are avoided. High-density polyethylene (HDPE) is a very stable polymer though it can be activated by gamma radiation to induce grafting. Glycidyl methacrylate was grafted onto macroporous HDPE and PP in the range of 1-6%, proportional to the initial monomer concentration. Grafted polymers were further chemically modified with ethylenediamine to generate a cationic hydrogel of micron-size thickness onto the internal polymer surfaces. Modified polymers were able to immobilize Gram-positive and Gram-negative bacteria that can catalyze a chemical reaction as efficient as free cells do.

2010-03-15

488

FB-Line resin testing final report

The Dowex 50W-X8 and 50W-Xl2 resin samples are both strong acid cation materials in the hydrogen form. Each material has a water retention capacity characteristic of its respective marketed degree of cross-linking. Dowex 21K gives confirmatory responses to tests for a strong anion exchange resin in the nitrate form. All three resins have the manufacturer's specified ionic type and form, and the Dowex 50W resins have characteristic water retention capacities. These tests conclude that the ion exchange resins in use in FB-Line meet the approved safety document criteria for cross-linking, ionic form, and resin type.

1992-01-23

489

Electrostatic droplets assisted synthesis of alginate microcapsules

The Dowex 50W-X8 and 50W-Xl2 resin samples are both strong acid cation materials in the hydrogen form. Each material has a water retention capacity characteristic of its respective marketed degree of cross-linking. Dowex 21K gives confirmatory responses to tests for a strong anion exchange resin in the nitrate form. All three resins have the manufacturer`s specified ionic type and form, and the Dowex 50W resins have characteristic water retention capacities. These tests conclude that the ion exchange resins in use in FB-Line meet the approved safety document criteria for cross-linking, ionic form, and resin type.

1992-01-23

490

British Library Electronic Table of Contents (United Kingdom)

This paper demonstrates a proof-of-concept approach for encapsulating the insulin and Fe3O4 nanoparticles into size-controllable alginate microcapsules utilizing the electrostatic droplets (ESD) technique. We have established that the combination of ESD and external gelation is quite effective in producing uniform-sized polymer particles. In addition, using the external gelation technique, the droplets containing a sodium-alginate were gelled in situ by immersion in Ca2+, Ba2+, or Cu2+ ions for a few minutes. The results show that different-type divalent cations caused various surface features to appear on the microcapsules (e.g., cracking, orange peel, pitting, splitting, wrinkling, etc.). The particle size can be adjusted from a few micrometers to ca. 1,000??m by electrostatic force. The...

2011-01-01

491

Effect of headgroup dissociation on the structure of Langmuir monolayers

Detrital processing in streams exposed to acidic precipitation in the Central Appalachian Mountains

The authors present results of grazing incidence X-ray diffraction studies concerning the effect of pH (and thus, of headgroup dissociation) on Langmuir monolayers of fatty acids, in the absence of any divalent cations in the aqueous subphase. An increase in pH transforms the distorted-hexagonal S phase first to the partially disordered Rotator-I phase with less distortion, and then to the completely disordered Rotator-II phase with an undistorted hexagonal structure. The S-Rotator-I and Rotator-I-Rotator-II transitions are pushed to lower temperatures with increase in pH. The fact that the effects of pH increase are almost identical to the effects of increasing temperature indicates the important role of headgroup-headgroup interactions in these monolayer phases.

2000-02-08

492

Comparison of antioxidant abilities of magnolol and honokiol to scavenge radicals and to protect DNA

Continuing high rates of acidic deposition in the eastern United States may lead to long-term effects on stream communities, because sensitive catchments are continuing to lose anions and cations. A two-year study of the effects of pH and associated water chemistry variables on detrital processing in three streams with different bedrock geology in the Monongahela National Forest, West Virginia were investigated. Leaf pack processing rates and macroinvertebrate colonization and microbial biomass (ATP concentration) on the packs in the three stream were compared. It was found that macroinvertebrate and microbial communities differed both among streams that differed in their capacity to buffer the effects of acidic precipitation and among years in the same stream; these differences in biotic communities were not large enough to affect rates of leaf processing between the two years of the study, but they did significantly affect processing rates between acidic and ...

493

British Library Electronic Table of Contents (United Kingdom)

The antioxidant properties of magnolol and honokiol were evaluated in the experimental systems of reducing ONOO^- and ^1O"2, bleaching @b-carotene in linoleic acid (LH) emulsion, and trapping 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonate) cationic radical (ABTS^+?) and 2,2'-diphenyl-1-picrylhydrazyl radical (DPPH), and then were applied to inhibit the oxidation of DNA induced by Cu^2^+/glutathione (GSH) and 2,2'-azobis(2-amidinopropane hydrochloride) (AAPH). Magnolol and honokiol were active to reduce ONOO^- and ^1O"2. Honokiol showed a little higher activity to protect LH and to inhibit Cu^2^+/GSH-induced oxidation of DNA than magnolol. In addition, honokiol exhibited higher activities to trap ABTS^+? and DPPH than magnolol. In particular, honokiol trapped 2.5 radicals while magnolol o...

2011-01-01

494

Chromate Transport through Surfactant-Modified Zeolite Columns

British Library Electronic Table of Contents (United Kingdom)

Abstract Remediation of ground water containing anionic contaminants presents a great challenge. Because of its low cost, surfactant-modified zeolite (SMZ) has been studied for >10 years for potential uses as permeable barrier materials to remove anionic contaminants from water. In this study, zeolite aggregates with particle size of 3.4 to 4.8 mm were modified by hexadecyltrimethylammonium (HDTMA) bromide, a cationic surfactant, to a surfactant loading level of 80 mmol/kg and a concurrent counterion bromide loading level of 34 mmol/kg. While no retardation of chromate transport was observed for unmodified columns, a retardation factor of 60 was found for chromate transport through the SMZ columns. Slow but persistent desorption of HDTMA occurred throughout the chromate transport experimen...

2006-01-01

495

Characterization of Y2BaCuO5 nanoparticles synthesized by nano-emulsion method

British Library Electronic Table of Contents (United Kingdom)

Nanoscale yttrium?barium?copper oxide (Y2BaCuO5, Y211) particles were synthesized using the emulsion method and the solution method. The basic water-in-oil (w/o) emulsion system consisted of n-octane (continuous oil phase), cetyltrimethylammonium bromide (cationic surfactant), butanol (cosurfactant) and water. The composition of the emulsion system was varied and characterized by measuring the conductivity of the solutions and droplet size. The droplet size of emulsion was determined by using the dynamic light scattering method. The water content, cosurfactant content, and surfactant/n-octane ratio affected the droplet size which was in the range of 3?8?nm, and hence the w/o emulsion system was referred to as a nano-emulsion system. A model was used to verify the droplet size. The influenc...

2007-01-01

496

Alkali metal and alkali metal hydroxide intercalates of the layered transition metal disulfides