Search

Introduction Imatinib, approved as first-line treatment for patients with newly diagnosed chronic myeloid leukemia (CML) by FDA approximately 20 years ago, revolutionized the treatment of this disease. The life expectancy of newly diagnosed patients with CML has been approaching that of the global population. Second generation TKI (2GTKI) administered as a frontline therapy can induce deeper and faster molecular responses in a higher percentage of patients, however, the overall survival is comparable to that achieved with imatinib. To investigate the outcomes of long-lasting therapy with imatinib administered as initial therapy, we analyzed patients with CML who received imatinib as initial therapy at our institution starting from 2001. Methods We retrospectively analyzed long term outcomes of 267 patients treated with imatinib 400 mg at the Department of Hematology, Jagiellonian University Medical College, Cracow, Poland from 2001. Data from medical records were collected and statistical analysis was performed using R software (R version 4.0.2). Results The median age was 53.5 (16 to 88 years), 129 of patients (pts) (48.31%) were female. At the time of this analysis, 99 pts (37.08 %) remained on imatinib with the median dose at last follow-up (FU) 400 mg. The mean initial dose of imatinib was 410.4 mg/d. Imatinib dose was increased in 53 pts (19.85%), up to 800mg and up to 600 mg in 3 pts (1.13%), and in 49 pts (18.35%) respectively. The mean maximal dose was 465.2 mg. At baseline 124 pts (46.44%) had comorbidities: 79 pts (29.59%) vascular/cardiac, 11 pts (4.12%) renal, and 101 pts (37.33%) other comorbidities. 15 patients (5.63%) had prior malignancies, newly diagnosed malignancies occurred among 11 (4.12%) pts on imatinib. The median follow-up time was 11.37 years (range from 2 months to 19.5 years). 168 pts (62.92%) discontinued imatinib permanently, the median time to imatinib discontinuation was 2.02 years. Among them, 123 pts (71.93 %) switched imatinib to 2GTKI- 79 pts (29.59%) to dasatinib, 68 pts (25.47%) to nilotinib, and 14 pts (5.24%) to bosutinib. During the following treatment 87 pts (32,58%) received one 2GTKI, 33 pts (12.36%) two, and 3 pts (1.12%) more than two 2GTKIs. The main reasons for imatinib therapy discontinuation were intolerance (87 pts, 32.58%) and disease progression (90 pts, 33.71%). The median time to the imatinib discontinuation due to its intolerance was 2 years. Adverse events (AEs) during imatinib therapy were as follows: cardiac/vascular AEs in 22 pts (8.24%), renal in 42 pts (15.73%), hematologic in 43 pts (16.10%), and other in 189 pts (70.79%). Overall, 28 patients died (10.5%), 7 pts (2.2%) transformed to blast phase, 9 pts (3.37%) underwent allo-HSCT. Estimated OS for patients that remained on imatinib for the whole observation period for 15 and 18 years was: 80.2%, and 64.1% respectively (Figure 1). Median follow-up time for patients who continued imatinib was 7.91 years. Intention to treat (ITT) analysis available for 99 pts (37.08%) revealed ITT responses at three months, one, five, ten and fifteen years: 50.52%, 77.4%, 86.25%, 90.28%, 100% for CCyR, 32.99%, 58.07%, 80%, 86.11%, 100% for MMR, 11.34%, 20.44%, 63.75%, 63.89%, 90% for MR4, 2.06%, 12.91%, 35%, 38.89%, 70% for MR4.5, 2.06%, 7.53%, 26.25%, 33.33%, 50% for CMR (undetectable transcripts with ≥100,000 copies ABL) (Table 1). The overall best response rates (at any time) for these 99 pts was 4.04% for MCyr, 5.05% for CCyR, 11.11% for MMR, 14.14% for MR4, 9.09% for MR4.5, 49.49% for CMR. Conclusion The analysis of long-term therapy with imatinib showed that the efficacy of imatinib persisted over time and that long-term administration of imatinib was associated with low rate of late toxic effects. Disclosures Sacha: Novartis: Consultancy, Honoraria, Speakers Bureau; Pfizer: Consultancy, Honoraria, Speakers Bureau; Adamed: Consultancy, Honoraria; Incyte: Consultancy, Honoraria, Speakers Bureau; Bristol-Myers Squibb Company: Consultancy, Honoraria, Speakers Bureau.

We have measured the kinetic energy distributions for the mutual neutralization of a large ensemble of atomic anions and cations. Ions are accelerated to equal velocities in a merged beam setup, enabling measurements at collision energies as low as 5 meV. Three-dimensional momentum imaging is performed with two position sensitive detectors located several meters downstream from the few centimeter long region where the beams overlap. An unprecedented resolution in the kinetic energy release (KER) spectra allows us to identify the states of both reactants and products down to their fine structure. Knowing the angular distribution of the products in the laboratory and center-of-mass frame, allows for total, partial, and differential cross sections to be retrieved., SCOPUS: cp.p, info:eu-repo/semantics/published

Spontaneous decays of small, hot silver-cluster anions ${\text{Ag}}_{n}^{\ensuremath{-}}$, $n=4--7$, have been studied using one of the rings of the Double ElectroStatic Ion Ring ExpEriment (DESIREE). Observation of these decays over very long time scales is possible due to the very low residual gas pressure ($\ensuremath{\sim}{10}^{\ensuremath{-}14}$) and cryogenic (13 K) operation of DESIREE. The yield of neutral particles from stored beams of ${\text{Ag}}_{6}^{\ensuremath{-}}$ and ${\text{Ag}}_{7}^{\ensuremath{-}}$ anions were measured for 100 milliseconds and were found to follow single power-law behavior with millisecond time-scale exponential cutoffs. The ${\text{Ag}}_{4}^{\ensuremath{-}}$ and ${\text{Ag}}_{5}^{\ensuremath{-}}$ anions were stored for 60 s and the observed decays show two-component power-law behaviors. We present calculations of the rate constants for electron detachment from and fragmentation of ${\text{Ag}}_{4}^{\ensuremath{-}}$ and ${\text{Ag}}_{5}^{\ensuremath{-}}$. In these calculations, we assume that the internal energy distribution of the clusters are flat and with this we reproduce the early steep parts of the experimentally measured decay curves for ${\text{Ag}}_{4}^{\ensuremath{-}}$ and ${\text{Ag}}_{5}^{\ensuremath{-}}$, which extends to tens and hundreds of milliseconds, respectively. The fact that the calculations reproduce the early slopes of ${\text{Ag}}_{4}^{\ensuremath{-}}$ and ${\text{Ag}}_{5}^{\ensuremath{-}}$, which differ for the two cases, suggests that it is the changes in fragmentation rates with internal cluster energies of ${\text{Ag}}_{4}^{\ensuremath{-}}$ and ${\text{Ag}}_{5}^{\ensuremath{-}}$ rather than conditions in the ion source that determine this behavior. Comparisons with the measurements strongly suggest that the neutral particles detected in these time domains originate from ${\text{Ag}}_{4}^{\ensuremath{-}}\ensuremath{\rightarrow}{\text{Ag}}_{3}^{\ensuremath{-}}+\text{Ag}$ and ${\text{Ag}}_{5}^{\ensuremath{-}}\ensuremath{\rightarrow}{\text{Ag}}_{3}^{\ensuremath{-}}+{\mathrm{Ag}}_{2}$ fragmentation processes.

A sputter ion source with a solid graphite target has been used to produce dianions with a focus on carbon cluster dianions, $\text{C}_{n}^{2-}$, with $n=7-24$. Singly and doubly charged anions from the source were accelerated together to kinetic energies of 10 keV per atomic unit of charge and injected into one of the cryogenic (13 K) ion-beam storage rings of the Double ElectroStatic Ion Ring Experiment facility at Stockholm University. Spontaneous decay of internally hot $\text{C}_{n}^{2-}$ dianions injected into the ring yielded $\text{C}^{-}$ anions with kinetic energies of 20 keV, which were counted with a microchannel plate detector. Mass spectra produced by scanning the magnetic field of a $90^{\circ}$ analyzing magnet on the ion injection line reflect the production of internally hot $\text{C}_{7}^{2-}-\text{C}_{24}^{2-}$ dianions with lifetimes in the range of tens of microseconds to milliseconds. In spite of the high sensitivity of this method, no conclusive evidence of $\text{C}_{6}^{2-}$ was found while there was a clear $\text{C}_{7}^{2-}$ signal with the expect isotopic distribution. An upper limit is deduced for a $\text{C}_{6}^{2-}$ signal that is two orders-of-magnitue smaller than that for $\text{C}_{7}^{2-}$. In addition, $\text{C}_{n}\text{O}^{2-}$ and $\text{CsCu}^{2-}$ dianions were detected., Comment: 6 pages, 6 figures

We apply near-threshold laser photodetachment to characterize the rotational quantum level distribution of OH- ions stored in the cryogenic ion-beam storage ring DESIREE at Stockholm University. We ...

Synopsis The decay of hot copper dimer anions is studied in a cryogenic storage ring. We detect atomic anion and neutral products and determine the fragmentation and vibrational autodetachment (VAD) rates separately. For short storage times the dimer anions predominantly decay by fragmentation of highly rotationally excited ions by tunneling through the rotational barrier. For storage times exceeding 100 ms, however, VAD is dominating. This process is driven by the very weak direct coupling between nuclear and electronic degrees of freedom.

We have measured the spontaneous neutral particle emission from copper-cluster anions (${\mathrm{Cu}}_{n}{}^{\ensuremath{-}}, n=3--6$) stored at cryogenic temperatures in one of the electrostatic ion storage rings of the Double ElectroStatic Ion Ring ExpEriment facility at Stockholm University. The measured rate of emission from the stored ${\mathrm{Cu}}_{3}{}^{\ensuremath{-}}$ ions follows a single power-law decay for about 1 ms but then decreases much more rapidly with time. The latter behavior may be due to a decrease in the density of available final states in ${\mathrm{Cu}}_{3}$ as the excitation energies of the decaying ions approach the electron detachment threshold. The emissions from ${\mathrm{Cu}}_{4}{}^{\ensuremath{-}}, {\mathrm{Cu}}_{5}{}^{\ensuremath{-}}$, and ${\mathrm{Cu}}_{6}{}^{\ensuremath{-}}$ are well described by sums of two power laws that are quenched by radiative cooling of the stored ions with characteristic times between a few and hundreds of milliseconds. We relate these two-component behaviors to populations of stored ions with higher and lower angular momenta. In a separate experiment, we studied the laser-induced decay of ${\mathrm{Cu}}_{6}{}^{\ensuremath{-}}$ ions that were excited by 1.13- or 1.45-eV photons after 46 ms of storage.

The intrinsic radiative lifetimes of the $5{d}^{10}6{s}^{}^{2}S_{1/2}$ and $5{d}^{9}6{s}^{2} ^{2}D_{3/2}$ bound excited states in the platinum anion ${\text{Pt}}^{\ensuremath{-}}$ have been studied at cryogenic temperatures at the Double ElectroStatic Ion Ring Experiment (DESIREE) facility at Stockholm University. The intrinsic lifetime of the higher-lying $5{d}^{10}6{s}^{} ^{2}S_{1/2}$ state was measured to be $2.54\ifmmode\pm\else\textpm\fi{}0.10\phantom{\rule{0.16em}{0ex}}\mathrm{s}$, while only a lifetime in the range of 50\char21{}200 ms could be estimated for the $5{d}^{9}6{s}^{2} ^{2}D_{3/2}$ fine-structure level. The storage lifetime of the ${\text{Pt}}^{\ensuremath{-}}$ ion beam was measured to be a little over 15 min at a ring temperature of $13\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. The present study reports the lifetime of an atomic negative ion in an excited bound state with an electron configuration different from that of the ground state.

Nitrile ions are abundant in Titan's upper atmosphere and are expected to be lost mainly via dissociative recombination with free electrons. We review in this paper a series of experimental results ...

We have investigated the dissociative recombination (DR) of the C 6 D 6 + and C 6 D 7 + ions using the CRYRING heavy-ion storage ring at Stockholm University, Sweden. The dissociative recombination branching ratios were determined at minimal collision energy, showing that the DR of both ions was dominated by pathways keeping the carbon atoms together in one product. The absolute reaction cross sections for the titular ions are best fitted by σ (E cm [eV]) = 1.3 ± 0.4 × 10 -15 (E cm [eV]) −1.19 ± 0.02 cm 2 (C 6 D 6 + ) and σ (E cm [eV]) = 1.1 ± 0.3 × 10 -15 (E cm [eV]) −1.33 ± 0.02 cm 2 (C 6 D 7 + ) in the intervals 3-300 meV and 3-200 meV respectively. The thermal rate constants of the titular reactions are best described by: k(T) = 1.3 ± 0.4 × 10 -6 (T/300) −0.69 ± 0.02 cm 3 s -1 for C 6 D 6 + and k(T) = 2.0 ± 0.6 × 10 -6 (T/300) −0.83 ± 0.02 cm 3 s -1 for C 6 D 7 + . These expressions correlates well with earlier flowing afterglow studies on the same process.

The dissociative recombination of protonated propionitrile, CH3CH2CNH+, has been investigated at the heavy ion storage ring, CRYRING, at the Manne Siegbahn Laboratory, Stockholm University, Sweden. ...

At the heavy ion storage ring CRYRING in Stockholm, Sweden, we have investigated the dissociative recombination of DCOOD2+ at low relative kinetic energies, from ~1 meV to 1 eV. The thermal rate coefficient has been found to follow the expression k(T) = 8.43 × 10-7 (T/300)^-0.78 cm3 s-1 for electron temperatures, T, ranging from ~10 to ~1000 K. The branching fractions of the reaction have been studied at ~2 meV relative kinetic energy. It has been found that ~87% of the reactions involve breaking a bond between heavy atoms. In only 13% of the reactions do the heavy atoms remain in the same product fragment. This puts limits on the gas-phase production of formic acid, observed in both molecular clouds and cometary comae. Using the experimental results in chemical models of the dark cloud, TMC-1, and using the latest release of the UMIST Database for Astrochemistry improves the agreement with observations for the abundance of formic acid. Our results also strengthen the assumption that formic acid is a component of cometary ices.

Measurements on the dissociative recombination (DR) of protonated acrylonitrile, CH2CHCNH+, have been performed at the heavy ion storage ring CRYRING located in the Manne Siegbahn Laboratory in Stockholm, Sweden. It has been found that at~2meV relative kinetic energy about 50% of the DR events involve only ruptures of X–H bonds (where X=C or N)while the rest leads to the production of a pair of fragments each containing two heavy atoms (alongside H and/or H2). The absolute DR cross section has been investigated for relative kinetic energies ranging from ~1 meV to 1 eV. The thermal rate coefficient has been determined to follow the expression k(T) = 1.78 × 10-6 (T/300)-0.80 cm3 s-1 for electron temperatures ranging from ~10 to 1000 K. Gas-phase models of the nitrile chemistry in the dark molecular cloud TMC-1 have been run and results are compared with observations. Also, implications of the present results for the nitrile chemistry of Titan’s upper atmosphere are discussed.

The possibility of an extraterrestrial origin of biomolecule building blocks has been a subject of intense discussions for many years. The detection of amino acids in meteorites opens the possibility of a delivery of biomolecules synthesized in the interstellar medium or star-forming regions to the primeval Earth. Whereas it can be doubted if more complex species like amino acids can survive the strong UV radiation in the early Solar System, this does not necessary hold for more primitive precursor molecules like nitriles. These compounds can also be synthesized very efficiently in methane-nitrogen dominated atmospheres like the one present on Titan and the early ages of Earth. This Contribution focuses on the formation and degradation processes of nitriles in interstellar clouds and planetary atmospheres and on their possible role in the generation of biomolecules.

The intrinsic lifetime of the upper level in the bound-bound $3{d}^{9}\phantom{\rule{0.16em}{0ex}}4{s}^{2}$ ${}^{2}{D}_{3/2} \ensuremath{\rightarrow} 3{d}^{9}\phantom{\rule{0.16em}{0ex}}4{s}^{2}$ ${}^{2}{D}_{5/2}$ radiative transition in ${\text{Ni}}^{\ensuremath{-}}$ was measured to be $15.1\ifmmode\pm\else\textpm\fi{}0.4\phantom{\rule{0.16em}{0ex}}\mathrm{s}$. The experiment was performed at cryogenic temperatures in one of the ion-beam storage rings of the Double ElectroStatic Ion Ring ExpEriment facility at Stockholm University. The storage lifetime of the ${\text{Ni}}^{\ensuremath{-}}$ ion beam was measured to be close to 5 min at a ring temperature of 13 K.

Experimental Near-Edge X-ray Absorption Fine-Structure (NEXAFS) spectra of N-methyltrifluoroacetamide (FNMA), which is a peptide model system, measured at the C, N, O and F K-edges are reported. The features in the spectra have been assigned by Static-Exchange (STEX) calculations. Using the same method, we have also assigned previously measured NEXAFS spectra of another peptide model system, N-methylacetamide (NMA). To facilitate the NEXAFS feature assignments, X-ray Photoelectron Spectroscopy (XPS) measurements for NMA and FNMA have been carried out with the aim of obtaining the 1s electron ionization potentials, which are compared with the values predicted by our Hartree-Fock (Delta HF) and Multi Configuration Self Consistent Field (Delta MCSCF) calculations. We also demonstrate an approach to compensate for screening effects that are neglected in the STEX method. Ion yield measurements of FNMA associated with the excitation of several C, N, O, and F K-shell pre-edge resonances have revealed site-specific fragmentation in some cases which we interpret with the aid of our theoretical calculations. QC 20160303

(2007). Experimental determination of dissociative recombination reaction pathways and absolute reaction cross-sections of CH2OH + , CD2OD + and CD2. Molecular Physics: Vol. 105, A Special Issue In Honour of John M. Brown, pp. 899-906.

We use a novel electrostatic ion storage ring to measure the radiative lifetime of the upper level in the 3p 5 P 2 o 1/2 →3p 5 P 2 o 3/2 spontaneous radiative decay in S − 32 to be 503±54 ...

Branching ratios and absolute cross sections have been measured for the dissociative recombination of HCS+ and OCS+ at the CRYRING ion storage ring. In the case of OCS+, the channel leading to CO + S (83%) dominates, whereas the other exoergic pathways leading to CS + O (14%) and C + SO (3%) are of lesser importance. In the case of HCS+, fracture of the C–S bond is predominant (81%), with the production of H + CS accounting for the remainder (19%). The cross section of the reaction could be fitted by the expressions σ = 1.41 × 10-15E(eV)-1.11 and 4.47 × 10-16E(eV)-1.14 cm2 for HCS+ and OCS+, respectively. The derived energy dependences of the thermal reaction rate coefficients can be fitted by k(T) = 9.7 × 10-7(T/300)-0.57 and 3.5 × 10-7(T/300)-0.62 cm3 s-1 for HCS+ and OCS+, respectively. We use these data to perform model calculations on the HCS+/CS abundance ratio in dark clouds and find that the models using the UMIST and Ohio State University databases have even more difficulty in accounting for the large observed ratio.

The dissociative recombination and excitation of CF+ have been measured at the ASTRID and CRYRING storage rings. Though examination of the available potential energy curves would suggest that the recombination rate would be large for this ion, in fact a rate constant of 5.2 ± 1.0 × 10−8 (Te/300)−0.8 cm3 s−1 was found. The recombination cross section at low energies falls off to a minimum at 0.5 eV centre-of-mass collision energy but exhibits resonances at energies above this. The dissociative excitation cross section leading to C+ + F was also measured and this displays an onset beginning at about 7 eV.

Cross sections and branching ratios for the dissociative recombination (DR) reactions of the astrophysically important ions HN2+, HCO+, DOCO+, and SO2+ at reactant kinetic energies from 1 to 1000 meV have been measured using the CRYRING ion storage ring facility at the Manne Siegbahn Laboratory, Stockholm University. Whereas the break-up of the N-N bond leading to NH + N is the major pathway in the DR of HN2+, the analogous reaction in HCO+ almost exclusively leads to H and CO. In the DR of both DOCO+ and SO2+ three-body break-up was observed. Inclusion of the newly measured branching ratios into a standard model on dark interstellar clouds leads to an improvement of the predictions of such models, especially concerning the abundances of nitrogen compounds. The impact of these newly found branching ratios and reaction rates on the chemistry of different astronomical environments like dark clouds, circumstellar envelopes and planetary ionospheres, is discussed.

Branching ratios and absolute cross sections have been measured for the dissociative recombination of DCCCN+ and DCCCND+ using the CRYRING ion storage ring. In the case of DCCCN+ the dissociation y ...

Branching ratios and absolute cross sections have been measured for the dissociative recombination of (SO2+)-O-18 using the CRYRING ion storage ring. The branching ratio of the (SO2+)-O-18 + e(-)-->(SO)-O-18+O-18 channel amounts to 61%, while the three-body breakup (SO2+)-O-18 + e(-)-->S+2(18)O accounts for the remaining 39% of the total reaction. The cross section of the reaction could be fitted by the expression sigma=(1.2+/-0.4)x10(-15) E-0.96+/-0.02 cm(2), which leads to a thermal reaction rate of k(T)=(4.6+/-0.2)x10(-7)(T/300 K)(-0.52+/-0.02) cm(3) mol(-1) s(-1).

An investigation into the dissociative recombination process for H(13)CO(+) using merged ion-electron beam methods has been performed at the heavy ion storage ring CRYRING, Stockholm, Sweden. We have measured the branching fractions of the different product channels at ∼ 0 eV collision energy to be the following: CO + H 87 ± 2%, OH + C 9 ± 2%, and O + CH 4 ± 2%. The formation of electronically excited CO in the dominant reaction channel has also been studied, and we report the following tentative branching fractions for the different CO product electronic states: CO(X (1)Σ(+)) + H, 54 ± 10%; CO(a (3)Π) + H, 23 ± 4%; and CO(a' (3)Σ(+)) + H, 23 ± 4%. The absolute cross section between ∼ 2-50 000 meV was measured and showed resonance structures between 3 and 15 eV. The cross section was fitted in the energy range relevant to astrophysics, i.e., between 1 and 300 meV, and was found to follow the expression σ = 1.3 ± 0.3 × 10(-16) E(-1.29 ± 0.05) cm(2) and the corresponding thermal rate constant was determined to be k(T) = 2.0 ± 0.4 × 10(-7)(T/300)(-0.79 ± 0.05) cm(3) s(-1). Radioastronomical observations with the IRAM 30 m telescope of HCO(+) toward the Red Rectangle yielded an upper column density limit of 4 × 10(11) cm(-2) of HCO(+) at the 1σ level in that object, indicating that previous claims that the dissociative recombination of HCO(+) plays an important role in the production of excited CO molecules emitting the observed Cameron bands in that object are not supported.

The fragmentation pattern of the peptide model system, N-methylacetamide, is investigated using ion time-of-flight (TOF) spectroscopy after resonant K-shell excitation. Corresponding near-edge X-ray absorption fine structure (NEXAFS) spectra recorded at high resolution at the C1s, N1s and O1s edges are presented. Analysis of the ion TOF data reveals a multitude of fragmentation channels and dissociation pathways. Comparison between the excitation of six different resonances in the vicinity of the C1s, N1s and O1s edges suggests evidence for site-selective bond breaking. In particular the breaking of the peptide bond and the N-C-alpha bond show a clear correlation with resonant excitation at the N1s edge. Also, stronger tendencies towards site-selective bond breaking are found for the generation of single ions compared with ion pairs. Analysis of angular distributions of ions from breakage of the peptide bond yields a fragmentation time of

We present a study into the collision-induced dissociation (possibly including electron stripping) of O-3(+) and N-3(+) with rest gas molecules (predominantly H-2) in the heavy-ion storage ring CRY ...

Covariance maps of correlated electron emission processes associated with the formation of multiply-ionized core hole states and subsequent decay processes of atoms and molecules upon absorption of x-ray photons from an FEL source are presented.

It is essential to establish whether and how environmental factors affect the reliability of [(13)C]methacetin breath test ((13)C-MBT). In 12 healthy volunteers (smokers), a standard (13)C-MBT with 75 mg [(13)C]methacetin was performed twice in random order: on a control day without smoking and on another day with smoking two cigarettes antecedently. A considerable flattening of the curve of the momentary (13)C recovery within the expiratory air was observed when the (13)C-MBT was performed after smoking. The maximum of the momentary (13)C recovery, D(max), decreased from 37.20±2.58 to 25.39±2.29% dose/h (p=0.00052). Moreover, the time to reach D(max) was prolonged after cigarette smoking (26.5±3.1 vs. 16.5±1.9 min, p=0.0199). The curve of the cumulative (13)C recovery on the cigarette smoking day appeared to be shifted downwards, and statistically significant differences relative to the control situation were found between the 24th and 75th minute following [(13)C]methacetin administration. Smoking cigarettes immediately prior to the (13)C-MBT diminishes the ability of the liver to handle methacetin, and hence a possibility of such an interaction should be excluded in order to interpret the results of the test correctly.

The dissociative recombination (DR) of CH{sub 5}{sup +} and CD{sub 5}{sup +} has been studied at the heavy-ion storage ring CRYRING. The fragmentation dynamics of the dominant reaction channel CH{sub 3}+H+H has been investigated using an imaging detector. The results indicate that a two-step process via the production of a CH{sub 4} intermediate, which has sufficient energy to fragment further to CH{sub 3}+H, may play an important role. Discrepancies between the present and earlier results obtained from storage ring measurements with those from flowing afterglow experiments are addressed. Newly measured branching fractions in the DR of CD{sub 5}{sup +} show an excellent agreement with branching fractions previously measured for CH{sub 5}{sup +}, and the absolute DR cross sections have been also measured over an interaction energy range between {approx}0 and 0.1 eV for both isotopologs.

We have investigated the dissociative recombination of the N2O+ ion using the CRYRING heavy-ion storage ring at the Manne Siegbahn laboratory in Stockholm, Sweden. The dissociative recombination branching ratios were determined at minimal (approximately 0 eV) collision energy, showing that the dominating pathways involved two-body fragmentation: N2 + O (48%) and NO + N (36%). The branching ratio of the three-body break-up 2N + O was 16%. The overall thermal rate coefficient of the title reaction follows the expression k(T) = 3.34 +/- 0.75 x 10(-7) (T/300) (-0.57+/- 0.03 cm3 s(-1)), which correlates perfectly with earlier flowing afterglow studies on the same process.

Dissociative recombination of BH$_2^+$: the dominance of two-body break-up and an understanding of the fragmentation

The dissociative recombination of fully deuterated protonated acetonitrile, CD(3)CND(+), has been investigated at the CRYRING heavy ion storage ring, located at the Manne Siegbahn Laboratory, Stockholm, Sweden. Branching fractions were measured at approximately 0 eV relative collision energy between the ions and the electrons and in 65% of the DR events there was no rupture of bonds between heavy atoms. In the remaining 35%, one of the bonds between the heavy atoms was broken. The DR cross-section was measured between approximately 0 eV and 1 eV relative collision energy. In the energy region between 1 meV and 0.1 eV the cross section data were best fitted by the expression sigma = 7.37 x 10(-16) (E/eV)(-1.23) cm(2), whereas sigma = 4.12 x 10(-16) (E/eV)(-1.46) cm(2) was the best fit for the energy region between 0.1 and 1.0 eV. From the cross section a thermal rate coefficient of alpha(T) = 8.13 x 10(-7) (T/300)(-0.69) cm(3) s(-1) was deduced.

The most up-to-date theoretical calculation on the dissociative recombination (DR) of D2H+ predicts a 2-5 times lower rate coefficient than that obtained experimentally at the Test Storage Ring (TSR). In order to verify the validity either of the experimental results or the theoretical calculations we have studied the DR of D2H+ at the storage ring CRYRING. The rate coefficient has been measured over the interaction energy range from approximate to 0 eV to 50 eV and has been found to have a peak at about 10 eV with a value of 1.6 x 10(-8) cm(3) s(-1), which is in excellent agreement with the result reported from TSR. Taking into account the electron temperature distributions, excellent agreement between the two storage rings measurements is also obtained at smaller interaction energies. The branching fraction analysis has been performed at approximate to 0 eV interaction energy and revealed the following results at the 1 sigma confidence level: N(D+D+H)=76.5%+/-2.2%, N(D-2+H)= 10.0%+/-0.7%, and N(DH+D)=13.5%+/-1.5%. The value of 2N(D-2+H)/N(DH+D)=1.48+/-0.22 implies that formation of D-2 is more favorable than DH.

We report an investigation into the dissociative recombination of the azide radical cation, N(3) (+). The reaction rate constant has been measured to be 6.47 x 10(-7) cm(3) s(-1) at room temperature. This value is smaller than those reported earlier for the ion-electron neutralization of N(3) (+) at nitrogen atmospheric pressure. A strong propensity to dissociate through the N(2)+N channel has been observed.

Dissociative recombination of the deuterated acetaldehyde ion CD3CDO(+) has been studied at the heavy-ion storage ring CRYRING, located at the Manne Siegbahn Laboratory, Stockholm, Sweden. Product branching fractions together with absolute DR cross-sections were measured. The branching fractions were determined at a relative collision energy between the ions and the electrons of approximately 0 eV. With a probability of 34% the DR events resulted in no ruptures of bonds between heavy atoms (i.e. no breakage of the C-C bond or the C[double bond, length as m-dash]O bond). In the remaining 66% of the events one of the bonds between the heavy atoms was broken. The energy-dependent cross-section for the DR reaction was measured between approximately 0 and 1 eV relative kinetic energy. In the energy region between 1 meV and 0.2 eV the absolute cross section could be fitted by the expression sigma(E) = 6.8 x 10(-16)E(-1.28) cm(2), whereas in the energy interval between 0.2 and 1 eV the data were best fitted by sigma(E) = 4.1 x 10(-16)E(-1.60) cm(2). From these cross section data the thermal rate coefficient (as a function of the electron temperature), alpha(T) = 9.2 x 10(-7) (T/300)(-0.72) cm(3) s(-1) was obtained.