Dynamical effects on the O(3P) + D2 reaction and its impact on the Λ-doublet population.

The O(3P) + D2 → OD(2Π) + D reaction presents the peculiarity of taking place on two different potential energy surfaces (PESs) of different symmetry, 3A' and 3A'', which become degenerate for collinear configurations where the saddle-point of the reaction is located. The degeneracy is broken for non-collinear approaches with the energy on the 3A' PES rising more abruptly with the bending angle, making the frequency of this mode higher on the 3A' state. Consequently, the 3A' PES should be less reactive than the 3A'' one. Nevertheless, quantum scattering calculations show that the cross section is higher on the 3A' PES for energies close to the classical reaction threshold and rotationless reactant. It is found that the differences between the reactivity on the two PESs are greater for low values of total angular momentum, where the centrifugal barrier is lower and contribute to the higher population of the Π(A') Λ-doublet states of OD at low collision energies. At high collision energies, the Π(A') Λ-doublet state is also preferentially populated. Analysis of the differential cross sections reveals that the preponderance for the Π(A') Λ-doublet at low energies comes from backward scattering, originating from the reaction on the 3A' PES, while at high energies, it proceeds from a different mechanism that leads to sideways scattering on the 3A'' PES and that populates the Π(A') manifold.

Data supporting the in situ synthesis by organometallic method of Vulcan supported PdNi nanostructures for hydrogen evolution reaction in alkaline solution.

This document presents the supporting information for the evaluation of the role of Ni amount during the in situ synthesis of vulcan supported PdNi nanostructures using an organometallic approach for hydrogen evolution reaction in alkaline medium [1]. The data here presented included analysis of deconvolution during structural characterization, chemical composition and transmission electron microscopy. The information also contains complement data of cyclic voltammograms during activation in alkaline media. Supplement data of electrochemical impedance spectroscopy measurements at two different overpotentials (-100 and -300 mV) and temperatures on the onset potential for hydrogen evolution reaction (HER) are also showed in this paper. The files can be used as a reference to determinate the effect of adding different in situ amount of Ni to Pd/C catalysts in presence of 2 equivalents of hexadecylamine (HDA) in order to improve the electrochemical performance on HER using an adjusted organometallic method. The data provided in this article have not been previously published and are available to enable critical or extended analyses.

HeH+ Collisions with H2: Rotationally Inelastic Cross Sections and Rate Coefficients from Quantum Dynamics at Interstellar Temperatures.

We report for the first time an accurate ab initio potential energy surface for the HeH+-H2 system in four dimensions (4D) treating both diatomic species as rigid rotors. The computed ab initio potential energy point values are fitted using an artificial neural network method and used in quantum close coupling calculations for different initial states of both rotors, in their ground electronic states, over a range of collision energies. The state-to-state cross section results are used to compute the rate coefficients over a range of temperatures relevant to interstellar conditions. By comparing the four dimensional quantum results with those obtained by a reduced-dimensions approach that treats the H2 molecule as an averaged, nonrotating target, it is shown that the reduced dimensionality results are in good accord with the four dimensional results as long as the HeH+ molecule is not initially rotationally excited. By further comparing the present rate coefficients with those for HeH+-H and for HeH+-He, we demonstrate that H2 molecules are the most effective collision partners in inducing rotational excitation in HeH+ cation at interstellar temperatures. The rotationally inelastic rates involving o-H2 and p-H2 excitations are also obtained and they turn out to be, as in previous systems, orders of magnitude smaller than those involving the cation. The results for the H2 molecular partner clearly indicate its large energy-transfer efficiency to the HeH+ system, thereby confirming its expected importance within the kinetics networks involving HeH+ in interstellar environments.

Efficiency of rovibrational cooling of HeH+ by collisions with He: Cross sections and rate coefficients from quantum dynamics.

By extending an earlier study [Gianturco et al., J. Chem. Phys. 154, 054311 (2021)] on the purely rotational excitation of HeH+ by He atoms, we report in this paper integral cross sections and rate coefficients for rovibrational excitation and de-excitation processes in HeH+ due to collisions with He. The data were obtained using a new ab initio potential energy surface that includes the vibrational degree of freedom. The results are compared with those computed using the earlier potential energy surface by Panda and Sathyamurthy [J. Phys. Chem. A 107, 7125 (2003)] that additionally accounts for the proton-exchange reaction between HeH+ and He. It is shown that the exchange channel contributes nearly as much as the inelastic channel to the vibrational excitation and de-excitation processes and that the total rate constants pertaining to the purely inelastic processes are largely of the same magnitude as those obtained when both inelastic and reactive channels are included in the dynamics. The inelastic rovibrational rate coefficients involving this astrophysical cation are also found to be much larger than those obtained for anions present in similar interstellar environments.

Multi- and single-reference methods for the analysis of multi-state peroxidation of enolates.

In spite of being spin-forbidden, some enzymes are capable of catalyzing the incorporation of O2(Σg-3) to organic substrates without needing any cofactor. It has been established that the process followed by these enzymes starts with the deprotonation of the substrate forming an enolate. In a second stage, the peroxidation of the enolate formation occurs, a process in which the system changes its spin multiplicity from a triplet state to a singlet state. In this article, we study the addition of O2 to enolates using state-of-the-art multi-reference and single-reference methods. Our results confirm that intersystem crossing is promoted by stabilization of the singlet state along the reaction path. When multi-reference methods are used, large active spaces are required, and in this situation, semistochastic heat-bath configuration interaction emerges as a powerful method to study these multi-configurational systems and is in good agreement with PNO-LCCSD(T) when the system is well-represented by a single-configuration.

Dynamics of HeHHe+ Rotational State Changes Induced by Collision with He: A Possible New Path in Early Universe Chemistry.

Ab initio calculations are employed to generate the rigid rotor (RR) potential energy surface (PES) describing the interaction of the linear molecular cation HeHHe+, at its equilibrium geometry, with the neutral He atom. The resulting interaction is employed to investigate the efficiency of rotational state-changing collisions at the temperatures relevant to the early universe conditions, where the latter molecule has been postulated to exist, albeit not yet observed. The inelastic rate coefficients are found to be fairly large and are compared with those found for another important cation just recently observed in the interstellar medium: the HeH+ polar molecule. The possibility for this cation to provide new options to energy dissipation routes under early universe conditions after the recombination era is briefly discussed.

Energy-transfer quantum dynamics of HeH+ with He atoms: Rotationally inelastic cross sections and rate coefficients.

Two different ab initio potential energy surfaces are employed to investigate the efficiency of the rotational excitation channels for the polar molecular ion HeH+ interacting with He atoms. We further use them to investigate the quantum dynamics of both the proton-exchange reaction and the purely rotational inelastic collisions over a broad range of temperatures. In current modeling studies, this cation is considered to be one of the possible cooling sources under early universe conditions after the recombination era and has recently been found to exist in the interstellar medium. The results from the present calculations are able to show the large efficiency of the state-changing channels involving rotational states of this cation. In fact, we find them to be similar in size and behavior to the inelastic and reaction rate coefficients obtained in previous studies, where H atoms were employed as projectiles. The same rotational excitation processes, occurring when free electrons are the collision partners of this cation, are also compared with the present findings. The relative importance of the reactive, proton-exchange channel and the purely inelastic channels is also analyzed and discussed. The rotational de-excitation processes are also investigated for the cooling kinetics of the present cation under cold trap conditions with He as the buffer gas. The implications of the present results for setting up more comprehensive numerical models to describe the chemical evolution networks in different environments are briefly discussed.

Unveiling shape resonances in H + HF collisions at cold energies.

Scattering resonances are pure quantum effects that appear whenever the collision energy matches the energy of a quasi-bound state of the intermolecular complex. Here we show that rotational quenching of HF(j = 1, 2) with H is strongly influenced by the presence of two resonance peaks, leading to up to a two-fold increase in the thermal rate coefficients at the low temperatures characteristic of the interstellar medium. Our results show that each resonance peak is formed by a cluster of shape resonances, each of them characterized by the same value of the orbital angular momentum but different values of the total angular momentum. The relative intensity of these resonances depends on the relative geometry of the incoming reactants, and our results predict that by changing the alignment of the HF rotational angular momentum it is possible to decompose the resonance peaks, disentangling the underlying resonance pattern and the contribution of different total angular momenta to the resonance.

Modeling state-selective photodetachment in cold ion traps: Rotational state "crowding" in small anions.

Using accurate ab initio calculations of the interaction forces, we employ a quantum mechanical description of the collisional state-changing processes that occur in a cold ion trap with He as a buffer gas. We generate the corresponding inelastic rates for rotational transitions involving three simple molecular anions OH-(1Σ), MgH-(1Σ), and C2H-(1Σ) colliding with the helium atoms of the trap. We show that the rotational constants of these molecular anions are such that within the low-temperature regimes of a cold ion trap (up to about 50 K), a different proportion of molecular states are significantly populated when loading helium as a buffer gas in the trap. By varying the trap operating conditions, population equilibrium at the relevant range of temperatures is reached within different time scales. In the modeling of the photodetachment experiments, we analyze the effects of varying the chosen values for photodetachment rates as well as the laser photon fluxes. Additionally, the changing of the collision dynamics under different buffer gas densities is examined and the best operating conditions, for the different anions, for yielding higher populations of specific rotational states within the ion traps are extracted. The present modeling thus illustrates possible preparation of the trap conditions for carrying out more efficiently state-selected experiments with the trapped anions.

Rotational 'cooling' and 'heating' of OH+(3Σ-) by collisions with He: quantum dynamics revealing propensity rules under ion trap conditions.

Multichannel scattering calculations are presented for the low-energy collisions of the OH+ cation and He atoms, using an ab initio evaluation of the interaction potential, which had been obtained in earlier work, and a time-independent, multichannel treatment of the quantum dynamics carried out in this study using our in-house scattering code ASPIN. Given the presence of spin-rotation coupling effects, within an essentially electrostatic formulation of the interaction forces with He atoms in the trap, the ensuing propensity rules which control the relative size of the state-changing cross sections and of the corresponding inelastic rates, also computed at the most likely temperatures in an ion trap, are presented and analysed in detail.

Modeling Quantum Kinetics in Ion Traps: State-changing Collisions for OH+ (3Σ- ) Ions with He as a Buffer Gas.

We present quantum scattering calculations for rotational state-changing cross sections and rates, up to about 50 K of ion translational temperatures, for the OH+ molecular ion in collision with He atoms as the buffer gas in the trap. The results are obtained both by using the correct spin-rotation coupling of angular momenta and also within a recoupling scheme that treats the molecular target as a pseudo-(1Σ+ ) state, and then compares our findings with similar data for the OH- (1Σ+ ) molecular partner under the same conditions. This comparison intends to link the cation behaviour to the one found earlier for the molecular anion. The full calculations including the spin-rotation angular momenta coupling effects have been recently reported (L. González-Sánchez and R. Wester and F.A. Gianturco, Mol.Phys.2018, DOI 10.1080/00268976.2018.1442597) with the aim of extracting specific propensity rules controlling the size of the cross sections. The present study is instead directed to modelling trap cooling dynamics by further obtaining the solutions of the corresponding kinetics equations under different trap schemes so that, using the presently computed rates can allow us to indicate specific optimal conditions for the experimental setup of the collisional rotational cooling in an ion trap for the system under study.

A Quantum Mechanical Study of the k-j and k'-j' Vector Correlations for the H + LiH → Li + H2 Reaction.

We have characterized the stereodynamics of the H + LiH (v = 0, j = 0-1) reactive collisions leading to H2 formation through the quantum mechanical analysis of the k-j and k'-j' vector correlations that describe the polarization of the reactants and products, respectively. Our results, which cover the collision energy interval between 10-4 and 1 eV, are unexpectedly complex given the apparent simplicity and featureless nature of the potential energy surface for the LiH2 system and point toward the existence of a dynamical barrier connected to the centrifugal barrier. Both reactants and products, in particular the second ones, display strong directional preferences in the cold region that indicate a bias for collinear approaching and departing geometries and are independent of the final state of the products. As more energy is available for the reaction, the polarization of reactants and products becomes weaker and strongly dependent on the final state. While stereodynamical control is feasible and significant in the cold region, its extent becomes negligible for other energetic regimes.

Contribution of JAK2 mutations to T-cell lymphoblastic lymphoma development.

The JAK-STAT pathway has a substantial role in lymphoid precursor cell proliferation, survival and differentiation. Nonetheless, the contribution of JAK2 to T-cell lymphoblastic lymphoma (T-LBL) development remains poorly understood. We have identified one activating TEL-JAK2 translocation and four missense mutations accumulated in 2 out of 16 T-LBL samples. Two of them are novel JAK2 mutations and the other two are reported for the first time in T-LBL. Notably, R683G and I682T might have arisen owing to RNA editing. Mutated samples showed different mutated transcripts suggesting sub-clonal heterogeneity. Functional approaches revealed that two JAK2 mutations (H574R and R683G) constitutively activate JAK-STAT signaling in γ2A cells and can drive the proliferation of BaF3-EpoR cytokine-dependent cell line. In addition, aberrant hypermethylation of SOCS3 might contribute to enhance the activation of JAK-STAT signaling. Of utmost interest is that primary T-LBL samples harboring JAK2 mutations exhibited increased expression of LMO2, suggesting a mechanistic link between JAK2 mutations and the expression of LMO2, which was confirmed for the four missense mutations in transfected γ2A cells. We therefore propose that active JAK2 contribute to T-LBL development by two different mechanisms, and that the use of pan-JAK inhibitors in combination with epigenetic drugs should be considered in future treatments.

A semiclassical treatment of the ℓ-j correlation in atom-diatom collisions.

The explicit consideration of the vector correlations is an essential step when it comes to determining the mechanism of chemical reactions. Usual vector correlations involve initial and final relative velocity vectors and rotational angular momenta. However, the correlation between the orbital, ℓ, and rotational, j, angular momenta has seldom received any attention. In this article, we present a semiclassical methodology capable of describing the ℓ-j correlation that may serve as a connection between the quantum and quasiclassical treatments. Using the scattering matrix in the orbital angular momentum representation, the ℓ-j correlation is expressed as a probability density function of the angle formed by both vectors. This technique is exemplified through the H + D2 reaction and its accuracy is appraised by comparing with results derived from calculations based on quasiclassical trajectories.

Influence of the Reactants Rotational Excitation on the H + D2(v = 0, j) Reactivity.

We have analyzed the influence of the rotational excitation on the H + D2(v = 0, j) reaction through quantum mechanical (QM) and quasiclassical trajectories (QCT) calculations at a wide range of total energies. The agreement between both types of calculations is excellent. We have found that the rotational excitation largely increases the reactivity at large values of the total energy. Such an increase cannot be attributed to a stereodynamical effect but to the existence of recrossing trajectories that become reactive as the target molecule gets rotationally excited. At low total energies, however, recrossing is not significant and the reactivity evolution is dominated by changes in the collision energy; the reactivity decreases with the collision energy as it shrinks the acceptance cone. When state-to-state results are considered, rotational excitation leads to cold product's rovibrational distributions, so that most of the energy is released as recoil energy.

Reaction dynamics and mechanism of the Cl + HD(v = 1) reaction: a quantum mechanical study.

Time-independent quantum mechanical calculations have been performed in order to characterize the dynamics and stereodynamics of Cl + HD reactive collisions. Calculations have been carried out at two different total energy values and for various initial states using the adiabatic potential energy surface by Bian and Werner [J. Chem. Phys. 2000, 112, 220]. Special attention has been paid to the reaction with HD(v = 1) for which integral and differential cross-sections have been calculated and the effect of vibrational vs translational energy on the reactivity has been examined. In addition, the reactant polarization parameters and polarization-dependent differential cross-sections have been determined. From these results, the spatial preferences of the reaction and the extent of the control of the cross sections achievable through a suitable preparation of the reactants have been also studied. The directional requirements are tighter for the HCl channel than for the DCl one. Formation of the products takes place preferentially when the rotational angular momentum of the HD molecule is perpendicular to the reactants approach direction. Cross-sections and polarization moments computed from the scattering calculations have been compared with experimental results by Kandel et al. [J. Chem. Phys. 2000, 112, 670] for the reaction with HD(v = 1) produced by stimulated Raman pumping. The agreement so obtained is good, and it improves the accordance found in previous calculations with other methodologies and potential energy surfaces.

Orientation effects in Cl + H2 inelastic collisions: characterization of the mechanisms.

Based on quantum mechanical scattering (QM) calculations, we have analyzed the polarization of the product hydrogen molecule in Cl + H(2) (v = 0, j = 0) inelastic collisions. The spatial arrangements adopted by the rotational angular momentum and internuclear axis of the departing molecule have been characterized and used to prove that two distinct mechanisms, corresponding to different dynamical regimes, are responsible for the inelastic collisions. Such mechanisms, named as low-b and high-b, correlate with well defined ranges of impact parameter values, add in an essentially incoherent way, and can be clearly differentiated through the quantum mechanical polarization moment that measures the orientation of the products rotational angular momentum with respect to the scattering plane. Other directional effects turn out to fail when it comes to distinguishing the mechanisms. Quasiclassical trajectories (QCT) calculations have been used as a supplement to the purely quantum mechanical analysis. By combining QM and QCT results, which are in very good agreement, we have succeeded in obtaining a clear and meaningful picture of how the two types of collisions take place.

Cross-sensitivity between taxanes in patients with breast cancer.

AIM This study was a retrospective analysis of our experience with severe cross-hypersensitivity reactions (HSR) to the taxanes paclitaxel (P) and docetaxel (D) in patients with breast cancer. PATIENTS AND METHODS We evaluated patients with breast cancer treated with P or D who experienced severe HSR to one of the two taxanes. Severe HSR was defined as any reaction severe enough to warrant discontinuation of the drug. Initial intravenous premedication for paclitaxel was dexamethasone (20 mg), ranitidine (50 mg) and dexchlorpheniramine (10 mg). For docetaxel, dexamethasone (4 mg) orally every 12 hours was administered the day before infusion and dexamethasone (20 mg) was administered intravenously prior to infusion. After severe HSR to the taxane and 30 minutes before infusion of another taxane, we administered dexamethasone (20 mg), ranitidine (50 mg) and dexchlorpheniramine (10 mg) iv as a premedication, and we also increased the time of the infusion. RESULTS Between March 2009 and April 2010, 23 patients experienced an initial severe HSR to taxane (12 P, 11 D). Substitution of another taxane was conducted in 17 patients in the two weeks following the initial HSR. Eight patients had an initial HSR with P, and three had a cross-HSR to D. Nine patients had an initial HSR to D, and four of these patients had a cross-HSR to P. Among the 17 patients who received both taxanes, 7 (41%) had a cross-HSR. All cross- HSRs were sufficiently severe (grade 3-4) to suspend taxane treatment permanently. In the remaining 6 patients, a desensitisation protocol to taxanes was performed by increasing the dose of the diluted drug (4 P, 2 D), which resulted in administration of the drug without complications in all cases. There were no treatment-related deaths. CONCLUSION Severe cross-HSR between P and D occurred in a significant proportion of our patients with breast cancer, so care must be taken when substituting taxanes (paclitaxel and docetaxel). A desensitisation protocol can be an effective alternative to decrease the risk of a new HSR.

Cross-sensitivity between taxanes in patients with breast cancer

AIM This study was a retrospective analysis of our experience with severe cross-hypersensitivity reactions (HSR) to the taxanes paclitaxel (P) and docetaxel (D) in patients with breast cancer. PATIENTS AND METHODS We evaluated patients with breast cancer treated with P or D who experienced severe HSR to one of the two taxanes. Severe HSR was defined as any reaction severe enough to warrant discontinuation of the drug. Initial intravenous premedication for paclitaxel was dexamethasone (20 mg), ranitidine (50 mg) and dexchlorpheniramine (10 mg). For docetaxel, dexamethasone (4 mg) orally every 12 hours was administered the day before infusion and dexamethasone (20 mg) was administered intravenously prior to infusion. After severe HSR to the taxane and 30 minutes before infusion of another taxane, we administered dexamethasone (20 mg), ranitidine (50 mg) and dexchlorpheniramine (10 mg) iv as a premedication, and we also increased the time of the infusion. RESULTS Between March 2009 and April 2010, 23 patients experienced an initial severe HSR to taxane (12 P, 11 D). Substitution of another taxane was conducted in 17 patients in the two weeks following the initial HSR. Eight patients had an initial HSR with P, and three had a cross-HSR to D. Nine patients had an initial HSR to D, and four of these patients had a cross-HSR to P. Among the 17 patients who received both taxanes, 7 (41%) had a cross-HSR. All cross- HSRs were sufficiently severe (grade 3-4) to suspend taxane treatment permanently. In the remaining 6 patients, a desensitisation protocol to taxanes was performed by increasing the dose of the diluted drug (4 P, 2 D), which resulted in administration of the drug without complications in all cases. There were no treatment-related deaths. CONCLUSION Severe cross-HSR between P and D occurred in a significant proportion of our patients with breast cancer, so care must be taken when substituting taxanes (paclitaxel and docetaxel). A desensitisation protocol can be an effective alternative to decrease the risk of a new HSR (AU)