Dynamical Outcomes of Quenching: Reflections on a Conical Intersection

This review focuses on experimental studies of the dynamical outcomes following collisional quenching of electronically excited OH A² ∑ ⁺ radicals by molecular partners. The experimental observables include the branching between reactive and nonreactive decay channels, kinetic energy release and quantum state distributions of the products. Complementary theoretical investigations reveal regions of strong nonadiabatic coupling, known as conical intersections, which facilitate the quenching process. The dynamical outcomes observed experimentally are connected to the local forces and geometric properties of the nuclei in the conical intersection region. Dynamical calculations for the benchmark OH-H₂ system are in good accord with experimental observations, demonstrating that the outcomes reflect the strong coupling in the conical intersection region as the system evolves from the excited electronic state to quenched products

A versatile, pulsed anion source utilizing plasma-entrainment: Characterization and applications

A novel pulsed anion source has been developed, using plasma entrainment into a supersonic expansion. A pulsed discharge source perpendicular to the main gas expansion greatly reduces unwanted “heating” of the main expansion, a major setback in many pulsed anion sources in use today. The design principles and construction information are described and several examples demonstrate the range of applicability of this anion source. Large OH−(Ar)n clusters can be generated, with over 40 Ar solvating OH−. The solvation energy of OH−(Ar)n, where n = 1-3, 7, 12, and 18, is derived from photoelectron spectroscopy and shows that by n = 12-18, each Ar is bound by about 10 meV. In addition, cis– and trans– HOCO− are generated through rational anion synthesis (OH− + CO + M → HOCO− + M) and the photoelectron spectra compared with previous results. These results, along with several further proof-of-principle experiments on solvation and transient anion synthesis, demonstrate the ability of this source to efficiently produce cold anions. With modifications to two standard General Valve assemblies and very little maintenance, this anion source provides a versatile and straightforward addition to a wide array of experiments

Photoelectron Spectroscopy of the Thiazate (NSO–) and Thionitrite (SNO–) Isomer Anions

Anion photoelectron spectra of the thiazate (NSO‾) and thionitrite (SNO‾) isomers are reported. The NSO‾ photoelectron spectrum showed several well-resolved vibronic transitions from the anion to the NSO radical neutral. The electron affinity of NSO was determined to be 3.113(1) eV. The fundamental vibrational frequencies of NSO were measured and unambiguously assigned to be 1202(6) cm‾¹ (ν₁, asymmetric stretch), 1010(10) cm‾¹ (ν₂, symmetric stretch), and 300(7) cm‾¹ (ν₃, bend). From the presence of vibrational hot band transitions, the fundamental vibrational frequencies of the NSO‾ anion were also measured: 1280(30) cm‾¹ (ν₁, asymmetric stretch), 990(20) cm‾¹ (ν₂, symmetric stretch), and 480(10) cm‾¹ (ν₃, bend). Combined with the previously measured ΔacidH⁰₂₉₈ K(HNSO), D₀(H‾NSO) was found to be 102(5) kcal/mol. Unlike the results from NSO‾, the SNO‾ photoelectron spectrum was broad with little structure, indicative of a large geometry change between the anion and neutral radical. In addition to the spectrally congested spectrum, there was evidence of a competition between photodetachment from SNO‾ and SNO‾ photodissociation to form S‾ + NO. Quantum chemical calculations were used to aid in the interpretation of the experimental data and agree well with the observed photoelectron spectra, particularly for the NSO‾ isomer

Photoelectron Spectroscopy of the Aminomethoxide Anion, H₂C(NH₂)O⁻

We report the photoelectron spectrum of the aminomethoxide anion (H₂C(NH₂)O⁻). The electron affinity (EA) of the aminomethoxy radical is determined to be 1.944(1) eV. Transitions to the ground (X̃ ²A″) and first excited (Ã ²A′) electronic states of aminomethoxy are observed, with the term energy measured to be T₀(Ã ← X̃) = 0.085(1) eV. A long vibrational progression is observed for the transition to the ground X̃ ²A″ electronic state of aminomethoxy, primarily consisting of OCN bending and HNH wagging vibrations, leading to the assignment of these two fundamental vibrational frequencies of H₂C(NH₂)O· X̃ ²A″. The gas-phase acidity of aminomethanol is calculated at the G4 level of theory to be ΔacidH0Ko = 374.0 kcal mol⁻¹, which, when combined with the experimental EA of aminomethoxy in a thermochemical cycle, provides a determination of the O–H bond dissociation energy, D₀(H₂C(NH₂)O–H) as 106(2) kcal mol⁻¹. Comparisons of the EAs and T₀(Ã ← X̃) for the aminomethoxy, methoxy, ethoxy, and hydroxymethoxy radicals provides insight into how the substituent group affects the electronic structure of singly substituted alkoxy radicals

Experimental, theoretical, and astrochemical modelling investigation of the gas-phase reaction between the amidogen radical (NH2) and acetaldehyde (CH3CHO) at low temperatures

The first experimental study of the low-temperature kinetics of the gas-phase reaction of NH2 with acetaldehyde (CH3CHO) has been performed. Experiments were carried out using laser-flash photolysis and laser-induced fluorescence spectroscopy to create and monitor the temporal decay of NH2 in the presence of CH3CHO. Low temperatures relevant to the interstellar medium were achieved using a pulsed Laval nozzle expansion. Rate coefficients were measured over the temperature and pressure range of 29–107 K and 1.4–28.2 × 1016 molecules per cm3, with the reaction exhibiting a negative temperature dependence and a positive pressure dependence. The yield of CH3CO from the reaction has also been determined at 67.1 and 35.0 K, by observing OH produced from the reaction of CH3CO with added O2. Ab initio calculations of the potential energy surface (PES) were combined with Rice–Rampsberger–Kessel–Marcus (RRKM) calculations to predict rate coefficients and branching ratios over a broad range of temperatures and pressures. The calculated rate coefficients were shown to be sensitive to the calculated density of states of the stationary points, which in turn are sensitive to the inclusion of hindered rotor potentials for several of the vibrational frequencies. The experimentally determined rate coefficients and yields have been used to fit the calculated PES, from which low-pressure limiting rate coefficients relevant to the ISM were determined. These have been included in a single-point dark cloud astrochemical model, in which the reaction is shown to be a potential source of gas-phase CH3CO radicals under dark cloud conditions

New Horned Dinosaurs from Utah Provide Evidence for Intracontinental Dinosaur Endemism

Background:\ud During much of the Late Cretaceous, a shallow, epeiric sea divided North America into eastern and western landmasses. The western landmass, known as Laramidia, although diminutive in size, witnessed a major evolutionary radiation of dinosaurs. Other than hadrosaurs (duck-billed dinosaurs), the most common dinosaurs were ceratopsids (large-bodied horned dinosaurs), currently known only from Laramidia and Asia. Remarkably, previous studies have postulated the occurrence of latitudinally arrayed dinosaur “provinces,” or “biomes,” on Laramidia. Yet this hypothesis has been challenged on multiple fronts and has remained poorly tested.\ud \ud Methodology/Principal Findings:\ud Here we describe two new, co-occurring ceratopsids from the Upper Cretaceous Kaiparowits Formation of Utah that provide the strongest support to date for the dinosaur provincialism hypothesis. Both pertain to the clade of ceratopsids known as Chasmosaurinae, dramatically increasing representation of this group from the southern portion of the Western Interior Basin of North America. Utahceratops gettyi gen. et sp. nov.—characterized by short, rounded, laterally projecting supraorbital horncores and an elongate frill with a deep median embayment—is recovered as the sister taxon to Pentaceratops sternbergii from the late Campanian of New Mexico. Kosmoceratops richardsoni gen. et sp. nov.—characterized by elongate, laterally projecting supraorbital horncores and a short, broad frill adorned with ten well developed hooks—has the most ornate skull of any known dinosaur and is closely allied to Chasmosaurus irvinensis from the late Campanian of Alberta.\ud \ud Conclusions/Significance:\ud Considered in unison, the phylogenetic, stratigraphic, and biogeographic evidence documents distinct, co-occurring chasmosaurine taxa north and south on the diminutive landmass of Laramidia. The famous Triceratops and all other, more nested chasmosaurines are postulated as descendants of forms previously restricted to the southern portion of Laramidia. Results further suggest the presence of latitudinally arrayed evolutionary centers of endemism within chasmosaurine ceratopsids during the late Campanian, the first documented occurrence of intracontinental endemism within dinosaurs

Combination therapy with rituximab and cyclophosphamide in the treatment of anti-neutrophil cytoplasmic antibodies (ANCA) positive pulmonary hemorrhage: case report

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) with pulmonary hemorrhage is rare in childhood. Standard treatment includes corticosteroids and cyclophosphamide (CYC), which is associated with a high level of toxicity. We report a white female with ANCA positive pulmonary hemorrhage who was treated with cyclophosphamide (CYC) and rituximab (RTX) combination therapy

Multi-Family Psycho-Education Group for Assertive Community Treatment Clients and Families of Culturally Diverse Background: A Pilot Study

This study evaluates the incorporation of Multi-Family Psycho-education Group (MFPG) to an Assertive Community Treatment Team developed to serve culturally diverse clients who suffers from severe mental illness. Participants included Chinese and Tamil clients and their family members. Family members’ well-being, perceived burden, and acceptance of clients were assessed before and after the intervention. Focus group interviews with clinicians were conducted to qualitatively examine MFPG. Family members’ acceptance increased after MFPG. Regular attendance was associated with reduction in perceived family burden. Culturally competent delivery of MFPG enhanced family members’ understanding of mental illness and reduced stress levels and negative feelings towards clients

Attitudes to antipsychotic drugs and their side effects: a comparison between general practitioners and the general population

BACKGROUND: Attitudes towards antipsychotic medication play an important part in the treatment for schizophrenia and related disorders. We aimed measuring general practitioners' attitudes to antipsychotic drugs and their adverse side effects and comparing these with the attitudes of the general population. METHODS: Analysis and comparison of two representative samples, one comprising 100 General Practitioners (GPs), the other 791 individuals randomly selected from the general population. The setting was the German speaking cantons of Switzerland. RESULTS: General practitioners have significantly more positive attitudes towards anti-psychotic drugs than the general public. They reject widespread prejudices about the use of anti-psychotic medication significantly more than the general population. In particular the risk of dependency was assessed as 'low' by GP's (80%), in contrast to only 18% of the general population sample. In no instance did a majority of the GPs advise not tolerating any of the 10 possible adverse effects presented in this study. This is in marked contrast to the general population sample, where a majority recommended discontinuation for movement disorder (63%), strong tremor (59%), risk of dependency (55%) and feelings of unrest (54%). CONCLUSION: As well as effective management of side-effects being a vital aspect of patient and carer education, prescribing doctors need to be aware that their mentally ill patients are likely to be confronted with extremely negative public attitudes towards antipsychotic medication and with strong pressures to stop taking their medication in the event of side-effects