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1.

001-es BibID:BIBFORM095780
Első szerző:Kéki Sándor (polimer kémikus)
Cím:A simple method for estimating activation energies using the fragmentation yield: Collision-induced dissociation of iron(II)-phenanthroline complexes in an electrospray ionization mass spectrometer / Sandor Keki, Lajos Nagy, Janos Torok, Gyorgy Deak, Miklos Zsuga
Dátum:2006
ISSN:1044-0305
Megjegyzések:The gas-phase stabilities of Fe(?){sub 3}{sup 2+} complexes, where ? represents the 1,10-phenanthroline, 5-chloro-1,10-phenanthroline, 5-methyl-1,10-phenanthroline, 3,4,7,8-tetramethyl-1,10-phenanthroline, and 4,7-diphenyl-1,10-phenanthroline ligands were investigated by collision-induced dissociation (CID) in the capillary-first skimmer region upon changing the voltage difference between the capillary and the skimmer. The loss of only one ligand from the Fe(?){sub 3}{sup 2+} complexes was observed with each of the phenanthroline ligands studied. An increase in the voltage difference between the capillary and the skimmer resulted in a higher fragmentation yield as calculated from the intensity of the precursor and the fragment ion. The fragmentation yield versus capillary-skimmer voltage difference plots were evaluated by means of the Arrhenius and the Rice-Ramsperger-Kassel (RRK) model by fitting the model parameters to the experimental data. Both models yielded practically the same results. In addition, if the internal energy gained through the capillary-skimmer region is estimated correctly, the approximate value of the critical energy (activation energy) for fragmentation can be extracted from the fragmentation yield versus capillary-skimmer voltage difference plots. It was found that the gas-phase stabilities of the Fe(?){sub 3}{sup 2+} complexes are nearly identical except for the more stable Fe(II)-4,7-diphenyl-1,10-phenanthroline complex. The critical energy for fragmentation was estimated to be ?1.2 and 0.9 eV for the Fe(II)-4,7-diphenyl-1,10-phenanthroline, and the other complexes, respectively.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Journal of The American Society For Mass Spectrometry. - 17 : 7 (2006), p. 962-966. -
További szerzők:Nagy Lajos (1979-) (vegyész) Török János Deák György (1954-) (polimer kémikus) Zsuga Miklós (1944-) (polimer kémikus)
Pályázati támogatás:T 037448
OTKA
T 042740
OTKA
M 28,369
OTKA
M 36,872
OTKA
MU-00,204/2001
OTKA
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2.

001-es BibID:BIBFORM085470
Első szerző:Kéki Sándor (polimer kémikus)
Cím:Multiple charging of poly(propylene glycol) by binary mixtures of cations in electrospray / Sándor Kéki, Lajos Nagy, György Deák, Miklós Zsuga
Dátum:2005
ISSN:1044-0305
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Journal of the American Society For Mass Spectrometry. - 16 : 2 (2005), p. 152-157. -
További szerzők:Nagy Lajos (1979-) (vegyész) Deák György (1954-) (polimer kémikus) Zsuga Miklós (1944-) (polimer kémikus)
Pályázati támogatás:T 037448
OTKA
T 042740
OTKA
M 28369
OTKA
M 36872
OTKA
MU-00204/2001
OTKA
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3.

001-es BibID:BIBFORM085053
Első szerző:Kéki Sándor (polimer kémikus)
Cím:Bimetallic silver-gold clusters by matrix-assisted laser desorption/ionization / Sándor Kéki, Lajos Nagy, György Deák, Miklós Zsuga
Dátum:2004
ISSN:1044-0305
Megjegyzések:Pure gold clusters (Aun+) were produced up to the cluster size of n = 100 by matrix-assisted laser desorption/ionization (MALDI). The mass spectrum of the resulting clusters showed alteration in the ion intensity at odd-even clusters size. On the other hand, intensity drops at cluster size predicted by the jellium model theory was also observed. Positively and negatively charged bimetallic silver-gold clusters were produced under MALDI conditions from the mixture of HAuCl4/silver trifluoroacetate and the 2-(4-hydroxyphenylazo)benzoic acid (HABA) matrix. A linear correlation was found between the intensity ratio of AunAgm+ to Aun+1Agm?1+ cluster ions and the molar ratio of the gold to silver salt. It was observed that the composition and the distribution of the clusters can be varied with the molar ratio of the silver and gold salts. It was also found that the resulting cluster sizes obey the lognormal distribution.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
folyóiratcikk
Megjelenés:Journal of The American Society for Mass Spectrometry. - 15 : 10 (2004), p. 1455-1461. -
További szerzők:Nagy Lajos (1979-) (vegyész) Deák György (1954-) (polimer kémikus) Zsuga Miklós (1944-) (polimer kémikus)
Pályázati támogatás:OTKA T 037448
OTKA
OTKA T 042740
OTKA
OTKA M 28369
OTKA
OTKA M 36872
OTKA
OTKA MU-00204/2001
OTKA
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4.

001-es BibID:BIBFORM023373
Első szerző:Kéki Sándor (polimer kémikus)
Cím:Cationization of simple organic molecules by singly-charged Ag3+ cluster ions in matrix-assisted laser desorption/ionization mass spectrometry: Metal cluster-molecule interactions / Sándor Kéki, Lajos Nagy, György Deák, Miklós Zsuga, László Somogyi, Albert Lévai
Dátum:2004
Megjegyzések:It was found earlier that under matrix-assisted laser desorption/ionization (MALDI) conditions several organic compounds which produce adduct with silver ions, are also capable of forming adducts with Ag3+ cluster ions under appropriate conditions. The Ag3+ cluster ion can be in situ generated under the MALDI analysis conditions from silver trifluoroacetate cationization agent in the presence of organic MALDI matrices. In this article the fragmentation of a commercial plasticizer, a peracetylated isoflavone glycoside and a pyrazolylphenyl disulfide derivative cationized with silver ions and Ag3+ cluster ions are compared. It was observed that the complexes of Ag3+ are less fragmented than the corresponding adduct ions with Ag+. The presumable fragmentation channel of [M + Ag3+] is the elimination of Ag2 units from these complexes. No significant dissociation of [M + Ag3+], into M and Ag3+ takes place, indicating a tight connection between the corresponding molecule and Ag3+ cluster ion. However, with a compound carrying very labile groups, such as the pyrazolylphenyl disulfide derivative, intramolecular cleavages can occur prior to significant dissociation of the Ag3+ cluster ion.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal of The American Society for Mass Spectrometry. - 15 : 6 (2004), p. 879-883. -
További szerzők:Nagy Lajos (1979-) (vegyész) Deák György (1954-) (polimer kémikus) Zsuga Miklós (1944-) (polimer kémikus) Somogyi László (1928-) (vegyész) Lévai Albert (1941-) (kémikus)
Pályázati támogatás:T 025016, T 037201, T 037448, T 042740, M 28369, M 36872, MU-00204/2001
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5.

001-es BibID:BIBFORM005398
Első szerző:Kéki Sándor (polimer kémikus)
Cím:Atmospheric Pressure Photoionization Mass Spectrometry of Polyisobutylene Derivatives / Sándor Kéki, János Török, Lajos Nagy, Miklós Zsuga
Dátum:2008
Megjegyzések:A detailed atmospheric pressure photoionization mass spectrometric (APPI-MS) study on three types of polyisobutylene derivatives is reported. Two of the polyisobutylenes investigated were polyisobutylene with dihydroxy and diolefinic end-groups derived from aromatic moieties [dicumyl chloride, 1,4-bis(2-chloro-2-propyl)benzene], and the third contained no aromatic moieties with a monohydroxy end-group. All three polyisobutylene derivatives (PIBs) had an average molecular weight (Mn) of ?2000 g/mol, with a polydispersity lower than 1.2. The experimental setup allowed the study of the influence of the end-group and the initiator moiety on the APPI-MS properties of these polymers. In the positive ion APPI mode, protonated PIB molecules were formed, but the molecular weights obtained were considerably lower than those expected, indicating fragmentation of the PIB chains. In the negative APPI mode, using solvents such as tetrahydrofuran and toluene as dopants, no signal was obtained. However, in chlorinated solvents, such as CCl4, CHCl3 and CH2Cl2, in the presence of toluene dopant, PIB adducts with chloride ions were formed with relatively high signal intensity. In the case of CH2Cl2, no dopant (toluene) was necessary to generate chlorinated adduct ions, albeit increasing the toluene concentration in the flow increased the PIB signal intensity. The effect of the toluene concentration (at a fixed total flow rate) on PIB signal intensity was thoroughly studied and models that include (i) photoionization of toluene, (ii) formation of chloride ions from the chlorinated solvents by dissociative electron capture, (iii) formation of chlorinated adduct ions and charge recombination reactions between the toluene radical cation, (iv) chloride ions, and (v) chlorinated adduct ions are proposed based on the experimental results.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Polyisobutylene
APPI-MS
mass spectrometry
chloride ion attachment
Megjelenés:Journal of the American Society for Mass Spectrometry. - 19 (2008), p. 656-665. -
További szerzők:Török János Nagy Lajos (1979-) (vegyész) Zsuga Miklós (1944-) (polimer kémikus)
Internet cím:DOI
elektronikus változat
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6.

001-es BibID:BIBFORM051769
Első szerző:Kuki Ákos (villamosmérnök)
Cím:Activation Energies of Fragmentations of Disaccharides by Tandem Mass Spectrometry / Ákos Kuki, Lajos Nagy, Katalin E. Szabó, Borbála Antal, Miklós Zsuga, Sándor Kéki
Dátum:2014
ISSN:1044-0305 (print) 1879-1123 (online)
Megjegyzések:A simple multiple collision model for collision induced dissociation (CID) in quadrupole was applied for the estimation of the activation energy (Eo) of the fragmentation processes for lithiated and trifluoroacetated disaccharides, such as maltose, cellobiose, isomaltose, gentiobiose and trehalose. The internal energy-dependent rate constants k(Eint) were calculated using the Rice-Ramsperger-Kassel-Marcus (RRKM) or the Rice-Ramsperger-Kassel (RRK) theory. The Eo values were estimated by fitting the calculated survival yield (SY) curves to the experimental ones. The calculated Eo values of the fragmentation processes for lithiated disaccharides were in the range of 1.4 - 1.7 eV, and were found to increase in the order trehalose < maltose < isomaltose < cellobiose < gentiobiose.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
multiple collisions
tandem mass spectrometry
collision-induced dissociation
RRK and RRKM model
disaccharides
Megjelenés:Journal Of The American Society For Mass Spectrometry 25 : 3 (2014), p. 439-443. -
További szerzők:Nagy Lajos (1979-) (vegyész) Szabó Erzsébet Katalin (1989-) (vegyész) Antal Borbála (1988-) (vegyész) Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
Pályázati támogatás:K-101850
OTKA
TÁMOP-4.2.2.A-11/1/KONV-2012-0036
TÁMOP
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7.

001-es BibID:BIBFORM047204
Első szerző:Kuki Ákos (villamosmérnök)
Cím:Estimation of Activation Energy from the Survival Yields : Fragmentation Study of Leucine Enkephalin and Polyethers by Tandem Mass Spectrometry / Ákos Kuki, Ghazaleh Shemirani, Lajos Nagy, Borbála Antal, Miklós Zsuga, Sándor Kéki
Dátum:2013
ISSN:1044-0305
Megjegyzések:A simple collision model for multiple collisions occurring in quadrupole type massspectrometers was derived and tested with Leucine enkaphalin a common mass spectrometricstandard with well-characterized properties. Implementation of the collision model and Rice?Ramsperger?Kassel?Marcus (RRKM) algorithm into a spreadsheet software allowed a goodfitting of the calculated data to the experimental survival yield (SY) versus collision energycurve. In addition, fitting also ensured to estimate the efficiencies of the kinetic to internalenergy conversion for Leucine enkephalin in quadrupole-time-of-flight and triple quadrupoleinstruments. It was observed that the experimental SY versus collision energy curves for theLeucine enkephalin can be described by the and Rice?Ramsperger?Kassel (RRK) formalismby reducing the total degrees of freedom (DOF) to about one fifth. Furthermore, this collisionmodel with the RRK formalism was used to estimate the critical energy (Eo) of lithiatedpolyethers including polyethylene glycol (PEG), polypropylene glycol (PPG) andpolytetrahydrofurane (PTHF) with degrees of freedom similar to that of Leucine enkephalin.Applying polyethers with similar DOF provided the elimination of the effect of DOF on theunimolecular reaction rate constant. The estimated value of Eo for PEG showed a relativelygood agreement with the value calculated by high-level quantum chemical calculationsreported in the literature. Interestingly, it was also found that the Eo values for the studiedpolyethers were similar.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Doktori iskola
Fizikai-, Számítás- és Anyagtudomány
Megjelenés:Journal Of The American Society For Mass Spectrometry. - 24 : 7 (2013), p. 1064-1071. -
További szerzők:Shemirani, Ghazaleh (1983-) (vegyész) Nagy Lajos (1979-) (vegyész) Antal Borbála (1988-) (vegyész) Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
Pályázati támogatás:K-101850
OTKA
TÁMOP-4.2.2/B-10/1-2010-0024
TÁMOP
Kémiai Tudományok Doktori Iskola
TÁMOP-4.2.2.A-11/1/KONV-2012-0036
TÁMOP
TÁMOP-4.2.1/B-09/1/KONV-2010-0007
TÁMOP
Orvosi és gyógyszerészeti célra alkalmas polimerbázisú nanokompozitok előállítása
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8.

001-es BibID:BIBFORM016383
Első szerző:Kuki Ákos (villamosmérnök)
Cím:Energy-dependent collision-induced dissociation of lithiated polytetrahydrofuran : Effect of the size on the fragmentation properties / Ákos Kuki, Lajos Nagy, Antony Memboeuf, László Drahos, Károly Vékey, Miklós Zsuga, Sándor Kéki
Dátum:2010
ISSN:1044-0305
Megjegyzések:The fragmentation properties of singly and doubly lithiated polytetrahydrofuran (PTHF) were studied using energy-dependent collision-induced dissociation. The product ion spectrum of [PTHF+Li]+ showed the formation of three different series corresponding to product ions with hydroxyl, aldehyde and vinyl end-groups. Interestingly, besides these series, two additional, non-lithiated product ions C4H9O+ and C4H7+ were identified in the MS/MS spectra. The MS/MS of the doubly lithiated PTHF ([PTHF+2Li]2+) with a number of repeat units ranging from 8 to 27 showed the formation of product ions similar to those of the singly lithiated series, however, doubly lithiated product ions and product ions formed by the loss of one Li+-ion from the precursor ion also appeared with significant abundances. Analysis of the breakdown curves for the singly and doubly charged PTHF indicated that the series A ions are formed most probably together with the series B ions, while members of the series C ions appeared at significantly higher collision energies. The fragmentation properties of [PTHF+Li]+ and [PTHF+2Li]2+ were also interpreted using the survival yield method. It was found that the collision energy/voltage necessary to obtain 50% fragmentation (CV50) was dependent linearly on the number of the repeat units, i.e., on the size, or the number of degrees of freedom (DOF).
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal Of The American Society For Mass Spectrometry. - 21 : 10 (2010), p. 1753-1761. -
További szerzők:Nagy Lajos (1979-) (vegyész) Memboeuf, Antony Drahos László Vékey Károly Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
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9.

001-es BibID:BIBFORM016386
Első szerző:Kuki Ákos (villamosmérnök)
Cím:Ligand size distribution of phenanthroline-functionalized polyethylene glycol-iron(II) complexes determined by electrospray ionization mass spectrometry and computer simulation / Ákos Kuki, Miklós Nagy, Lajos Nagy, Miklós Zsuga, Sándor Kéki
Dátum:2010
ISSN:1044-0305
Megjegyzések:The complex formation in solution, and the gas-phase dissociation of a phenanthroline-terminated poly(ethylene glycol) with Fe2+ ions were investigated. The size distribution of poly(ethylene glycol)-?-monomethyl-?-5-[1,10]phenanthroline (mPEG_phen) was determined by Electrospray Ionization Mass Spectrometry (ESI-MS). Based on the measured ligand size distribution of mPEG-phen by ESI-MS, the 1:3 complex formation (Fe2+/mPEG_Phen) was computer-simulated as a pure random assembly process. The simulated distribution fits excellently to that of the complex Fe(mPEG_Phen)32+ determined from the ESI-MS intensities. In addition, the collision-induced dissociation (CID) of the Fe(mPEG_phen)32+ complex was also studied by tandem mass spectrometry (ESI-MS/MS) and by computer simulation, as well. The ESI-MS/MS intensity distribution of the Fe(mPEG_phen)22+ formed from Fe(mPEG_phen)32+ by the loss of an mPEG_phen ligand under CID conditions fits quite well to the calculated one.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Journal Of The American Society For Mass Spectrometry. - 21 : 9 (2010), p. 1561-1564. -
További szerzők:Nagy Miklós (1976-) (vegyész) Nagy Lajos (1979-) (vegyész) Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
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10.

001-es BibID:BIBFORM064081
Első szerző:Nagy Lajos (vegyész)
Cím:Can Nonpolar Polyisobutylenes be Measured by Electrospray Ionization Mass Spectrometry? Anion-Attachment Proved to be an Appropriate Method / Lajos Nagy, Tibor Nagy, György Deák, Ákos Kuki, Mihály Purgel, Mijid Narmandakh, Béla Iván, Miklós Zsuga, Sándor Kéki
Dátum:2016
ISSN:1044-0305 1879-1123
Megjegyzések:Polyisobutylenes (PIBs) with different end-groups including chlorine, exoolefin,hydroxyl, and methyl prepared from aliphatic and aromatic initiators werestudied by electrospray ionization mass spectrometry (ESI-MS). Independently ofthe end-groups, presence or absence of aromatic initiator moiety, these PIB derivativeswere capable of forming adduct ions with NO3? and Cl? ions, thus allowing thedirect characterization of these compounds in the negative ion mode of ESI-MS. Toobtain [PIB + NO3]? and [PIB + Cl]? adduct ions with appreciable intensities, additionof polar solvents such as acetone, 2-propanol, or ethanol to the dichloromethanesolution of PIBs was necessary. Furthermore, increasing both the polarity (by increasingthe acetone content) and the ion-source temperature give rise to enhancedintensities for both [PIB + NO3]? and [PIB + Cl]? ions. Energy-dependent collision induced dissociation studies(CID) revealed that increasing the collision voltages resulted in the shift of the apparent molecular masses tohigher ones. CID studies also showed that dissociation of the [PIB + Cl]? ions requires higher collision energythan that of [PIB + NO3]?. In addition, Density Functional Theory calculations were performed to gain insights intothe nature of the interactions between the highly non-polar PIB chains and anions NO3? and Cl? as well as todetermine the zero-point corrected electronic energies for the formation of [PIB + NO3]? and [PIB + Cl]? adductions.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
ESI-MS
Polyisobutylenes
Nitrated adduct ions
Chlorinated adduct ions
Tandem mass spectrometry
Megjelenés:Journal Of The American Society For Mass Spectrometry. - 27 : 3 (2016), p. 432-442. -
További szerzők:Nagy Tibor (1988-) (vegyész) Deák György (1954-) (polimer kémikus) Kuki Ákos (1966-) (villamosmérnök) Purgel Mihály (1982-) (vegyész) Narmandakh, Mijid Iván Béla Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
Pályázati támogatás:TÁMOP-4.2.2.C-11/1/KONV-2012-0010
TÁMOP
K-101850
OTKA
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11.

001-es BibID:BIBFORM010304
Első szerző:Nagy Lajos (vegyész)
Cím:Dopant-Assisted Atmospheric Pressure Photoionization Mass Spectrometry of Polyisobutylene Derivatives Initiated by Mono- and Bifunctional Initiators / Lajos Nagy, Viktória Pálfi, Mijid Narmandakh, Ákos Kuki, Andrea Nyíri, Béla Iván, Miklós Zsuga, Sándor Kéki
Dátum:2009
Megjegyzések:Nine polyisobutylene (PIB) derivatives with different end groups (chlorine, vinyl, isobutenyl, 2,2-diphenylvinyl, and carboxyl) and molecular weights (1000 to 4500 g/mol), initiated by monofunctional and aromatic bifunctional initiators were studied by atmospheric pressure photoionization mass spectrometry (APPI-MS) in both the negative and the positive ion modes. Consistent with previous findings, negative ion APPI-MS revealed end-group identities through the formation of PIB adducts with chloride ions formed in situ from a chlorinated solvent (e.g., CCl4) in the presence of a dopant (toluene). In positive ion mode, considerable fragmentation of these PIB derivatives was observed, rendering end-group determinations very difficult. The Mn values obtained by APPI(-)-MS were considerably lower than those determined by SEC for PIB derivatives with Mn higher than 2000 g/mol. PIBs containing carboxyl termini can undergo collision-induced dissociation, yielding structurally important product ions. The resulting APPI-MS/MS intensities were found to reflect the "arm-length" distribution for PIBs with bifunctional aromatic moieties. In positive ion mode, [M+COCl]+ adducts were observed for PIBs with an aromatic initiator moiety. The origin of the COCl+ species is also discussed.
Tárgyszavak:Természettudományok Kémiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Polyisobutylene
APPI-MS
mass spectrometry
chloride ion attachment
Megjelenés:Journal of the American Society for Mass Spectrometry. - 20 : 12 (2009), p. 2342-2351. -
További szerzők:Pálfi Viktória Narmandakh, Mijid Kuki Ákos (1966-) (villamosmérnök) Nyíri Andrea Iván Béla Zsuga Miklós (1944-) (polimer kémikus) Kéki Sándor (1964-) (polimer kémikus)
Internet cím:DOI
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