Gas-phase bimolecular reactions of metal cations with water provide insights into intrinsic characteristics of hydrolysis. For the actinide dioxide cations, actinyl(V) AnO₂ ⁺ , melding of experiment and computation provides insights into trends for hydrolysis, as well as for oxo-exchange between actinyls and water that proceeds by a hydrolysis pathway. Here this line of inquiry is further extended into the actinide series with CCSD(T) computations of potential energy surfaces, for the reaction pathway for oxo-exchange through hydrolysis of nine actinyl(V) ions, from PaO₂ ⁺ to EsO₂ ⁺ . The computed surfaces are in accord with previous experimental results for oxo-exchange, and furthermore predict spontaneous exchange for CmO₂ ⁺ , BkO₂ ⁺ , CfO₂ ⁺ and EsO₂ ⁺ , but not for AmO₂ ⁺ . Natural Bond Order analysis of the species involved in both hydrolysis and oxo-exchange reveals an inverse correlation between the barrier to hydrolysis and the charge on the actinide centre, q(An). Based on this correlation, it can be concluded that hydrolysis, and related phenomena such as oxo-exchange, become less favourable as the charge on the metal centre decreases. The new results provide a straightforward rationalization of trends across a wide swathe of the actinide series.

The potential energy surfaces for the reactions of H2O with ThO2, PaO2(+), UO2(2+), and UO2(+) have been calculated at the coupled cluster CCSD(T) level extrapolated to the complete basis set limit with additional corrections including scalar relativistic and spin-orbit. The reactions proceed by the formation of an initial Lewis acid-base adduct (H2O)AnO2(0/+/2+) followed by a proton transfer to generate the dihydroxide AnO(OH)2(0/+/2+). The results are in excellent agreement with mass spectrometry experiments and prior calculations of hydrolysis reactions of the group 4 transition metal dioxides MO2. The differences in the energies of the stationary points on the potential energy surface are explained in terms of the charges on the system and the populations on the metal center. The use of an improved starting point for the coupled cluster CCSD(T) calculations based on density functional theory with the PW91 exchange-correlation functional or Brueckner orbitals is described. The importance of including second-order spin-orbit corrections for closed-shell molecules is also described. These improvements in the calculations are correlated with the 5f populations on the actinide.

A family of HY zeolite-supported cationic organoiridium carbonyl complexes was formed by reaction of Ir(CO)2 (acac) (acac=acetylacetonate) to form supported Ir(CO)2 complexes, which were treated at 298 K and 1 atm with flowing gas-phase reactants, including C2 H4 , H2 , (12) CO, (13) CO, and D2 O. Mass spectrometry was used to identify effluent gases, and infrared and X-ray absorption spectroscopies were used to characterize the supported species, with the results bolstered by DFT calculations. Because the support is crystalline and presents a nearly uniform array of bonding sites for the iridium species, these were characterized by a high degree of uniformity, which allowed a precise determination of the species involved in the replacement, for example, of one CO ligand of each Ir(CO)2 complex with ethylene. The supported species include the following: Ir(CO)2 , Ir(CO)(C2 H4)2 , Ir(CO)(C2 H4), Ir(CO)(C2 H5), and (tentatively) Ir(CO)(H). The data determine a reaction network involving all of these species.

Dinuclear perchlorate complexes of uranium, neptunium, and plutonium were characterized by reactivity and DFT, with results revealing structures containing pentavalent, hexavalent, and heptavalent actinyls, and actinyl-actinyl interactions (AAIs). Electrospray ionization produced native complexes [(AnO₂)₂(ClO₄)₃]^- for An:An = U:U, Np:Np, Pu:Pu, and Np:Pu, which are intuitively formulated as actinyl(V) perchlorates. However, DFT identified lower-energy structures [(AnO₂)(AnO₃)(ClO₄)₂(ClO₃)]^- comprising a perchlorate fragmented to ClO₃, actinyl(VI) cation An^VIO₂²⁺, and neutral AnO₃. For U:U and Np:Np, and Np in Np:Pu, the coordinated AnO₃ is calculated as actinyl(VI) with an equatorial oxo, [O_yl═An^VI═O_yl][═O_eq], whereas for Pu:Pu, it is plutonyl(V) oxyl, [O_yl═Pu^V═O_yl][-O_eq^•]. The implied lower stability of Pu^VI versus Np^VI indicates weaker Pu═O_eq versus Np═O_eq bonding. Adsorption of O₂ by the U:U complex suggests oxidation of U^V to U^VI, corroborating the assignment of perchlorate [(An^VO₂)₂(ClO₄)₃]^-. DFT predicts the O₂ adducts are [(An^VIO₂)(O₂)(An^VIO₂)(ClO₄)₃]^- with actinyls oxidized from +V to +VI by bridging peroxide, O₂^2-. In accordance with reactivity, O^2- addition is computed as substantially exothermic for U:U and least favorable for Pu:Pu. Collision-induced dissociation of native complexes eliminated ClO₂ to yield [(AnO₂)(O)₂(AnO₂)(ClO₄)₂]^-, in which fragmented O atoms bridge as oxyl O^-• and oxo O^2- to yield uranyl(VI) and plutonyl(VI), or as oxos O^2- to yield neptunyl(VII), [O_yl═Np^VII═O_yl]³⁺.

Objectives

Ecological momentary assessment (EMA) has several advantages in clinical research yet little is known about the feasibility of collecting EMA data with mobile technologies in older adults, particularly those with emotional or cognitive difficulties. The aim of this feasibility study was to assess perceived acceptability, adherence rates, and reasons for non-adherence to smartphone-based EMA.

Method

At two sites, participants (n=103) aged 65 years or older with a DSM-IV-defined anxiety or depressive disorder and cognitive concerns responded three times daily to smartphone-based EMA questions assessing clinical outcomes for two 10-day periods. Quantitative and qualitative measures assessed acceptability, adherence, and reasons for non-adherence following both 10-day EMA periods.

Results

Participants were moderately satisfied with and comfortable using smartphone-based EMA. Overall, 76% of participants completed surveys on ≥10 of the 20 assessment days, and 70% of participants completed at least 30% of the total surveys. Reasons for non-adherence included technical (malfunction), logistical (competing demands), physiological (hearing difficulties), and cognitive (forgetting) issues.

Discussion

Smartphone-based EMA is feasible in older adults with cognitive and emotional difficulties. EMA tools should be responsive to the needs and preferences of participants to ensure adequate acceptability and adherence in this population. Our findings can inform the design, development, and implementation of mobile technologies in older adults in research and clinical contexts.

Actinyl chemistry is extended beyond Cm to BkO₂⁺ and CfO₂⁺ through transfer of an O atom from NO₂ to BkO⁺ or CfO⁺ , establishing a surprisingly high lower limit of 73 kcal mol^-1 for the dissociation energies, D[O-(BkO⁺ )] and D[O-(CfO⁺ )]. CCSD(T) computations are in accord with the observed reactions, and characterize the newly observed dioxide ions as linear pentavalent actinyls; these being the first Bk and Cf species with oxidation states above IV. Computations of actinide dioxide cations AnO₂⁺ for An=Pa to Lr reveal an unexpected minimum for D[O-(CmO⁺ )]. For CmO₂⁺ , and AnO₂⁺ beyond EsO₂⁺ , the most stable structure has side-on bonded η² -(O₂ ), as An^III peroxides for An=Cm and Lr, and as An^II superoxides for An=Fm, Md, and No. It is predicted that the most stable structure of EsO₂⁺ is linear [O=Es^V =O]⁺ , einsteinyl, and that FmO₂⁺ and MdO₂⁺ , like CmO₂⁺ , also have actinyl(V) structures as local energy minima. The results expand actinide oxidation state chemistry, the realm of the distinctive actinyl moiety, and the non-periodic character towards the end of the periodic table.

Gas-phase reactions of pentavalent metal dioxide cations M^VO₂⁺ with water were studied experimentally for M = V, Nb, Ta, Pr, Pa, U, Pu, and Am. Addition of two H₂O can occur by adsorption to yield hydrate (H₂O)₂M^VO₂⁺ or by hydrolysis to yield hydroxide M^V(OH)₄⁺. Displacement of H₂O by acetone indicates hydrates for Pr^V, U^V, Pu^V, and Am^V, whereas nondisplacement indicates hydroxides for Nb^V, Ta^V, and Pa^V. Computed potential energy profiles agree with the experimental results and furthermore indicate that acetone unexpectedly induces dehydrolysis and displaces two H₂O from (H₂O)VO(OH)₂⁺ to yield (acetone)₂VO₂⁺. Structures and energies for several M^V, as well as for Th^IV and U^VI, indicate that hydrolysis is governed by the involvement of valence f versus d orbitals in bonding: linear f-element dioxides are more resistant to hydrolysis than bent d-element dioxides. Accordingly, for early actinides, hydrolysis of Th^IV is characteristic of a 6d-block transition metal; hydration of U^V and U^VI is characteristic of 5f actinyls; and Pa^V is intermediate between 6d and 5f. The praseodymium oxide cation Pr^VO₂⁺ is assigned as an actinyl-like lanthanyl with properties governed by 4f bonding.

Objectives

Elevated cortisol in stress and aging, such as has been seen in late-life anxiety disorders, is postulated to accelerate cognitive and physiological decline in this large and increasing population. Selective serotonin-reuptake inhibitors (SSRIs) and cognitive-behavioral therapy (CBT) are both effective treatments for generalized anxiety disorder (GAD) in older adults. On the other hand, there is very little research examining the effect of combining these therapies on peak cortisol levels. For the current analyses, we examined the effectiveness of CBT augmentation on peak cortisol levels in older adults diagnosed with GAD.

Methods

The sample consisted of 42 individuals with late-life GAD who received an acute course of the SSRI escitalopram and then entered a 16-week randomized phase. Twenty-one participants were randomized to receive 16 sessions of CBT in addition to continuing escitalopram and the remaining 21 participants continued on escitalopram without CBT. Generalized estimating equations were performed to assess the effectiveness of CBT augmentation on peak cortisol levels (30 min after waking).

Results

Older adults with GAD who received both escitalopram and CBT demonstrated a significant reduction in peak cortisol levels at posttreatment compared to the group who received escitalopram without CBT augmentation.

Conclusions

CBT augmentation of SSRI treatment reduced peak cortisol levels for older adults with GAD. Since persistently high cortisol levels in aging are thought to increase age-related cognitive and medical problems, our findings suggest that there may be a benefit to health and cognition of CBT augmentation for late-life anxiety disorders.

The isolated gas-phase actinide dioxide dications, AnO₂²⁺, were evaluated by DFT and coupled cluster CCSD(T) calculations for 12 actinides, An = U-Lr. CASSCF calculations were used to define the orbitals for the CCSD(T) calculations. The characteristic linear [O═An═O]²⁺ hexavalent actinyl(VI) was found to be the lowest energy structure for An = U, Np, and Pu, which also form stable actinyl(VI) species in solution and possibly for Am when spin-orbit effects are included. For Am, there is a divalent [An^II(O₂)]²⁺ structure where the dioxygen is an end-on physisorbed η¹-³O₂ 2 kcal/mol above the actinyl when spin-orbit effects are included which lower the energy of the actinyl structure. For An = Cm, Bk, and Lr, the lowest energy structure is trivalent [An^III(O₂^-)]²⁺ where the dioxygen is a side-on superoxide, η²-O₂^-. For Cm, the actinyl is close in energy to the ground state when spin-orbit effects are included. For An = Cf, Es, Fm, Md, and No, the lowest energy structure is divalent [An^II(O₂)]²⁺ where the dioxygen is an end-on physisorbed η¹-³O₂. The relative energies suggest that curyl(VI) and berkelyl(VI), like well-known americyl(VI), might be stabilized by coordinating ligands in condensed phases. The results further indicate that for californyl and beyond, the actinyl(VI) moieties will probably be elusive even using strong donor ligands. The prevalence of low oxidation states (OSs) An(II) and An(III) for transplutonium actinides reflects stabilization of the 5f orbitals and validates established trends, including the remarkably high stability of divalent No. Bond distances and other parameters suggest maximum bond covalency around plutonyl(VI), with a particularly substantial decrease in bond strength between americyl(VI) and curyl(VI).