Fluoroform (CHF) Production from CFCHO Photolysis and Implications for the Decomposition of Hydrofluoroolefins and Hydrochlorofluoroolefins in the Atmosphere.

Hydrofluoroolefins (HFOs) and hydrochlorofluoroolefins (HCFOs) are the leading synthetic replacements for compounds successively banned by the Montreal Protocol and amendments. HFOs and HCFOs readily decompose in the atmosphere to form fluorinated carbonyls, including CFCHO in yields of up to 100%, which are then photolyzed. A long-standing issue, critical for the transition to safe industrial gases, is whether atmospheric decomposition of CFCHO yields any quantity of CHF (HFC-23), which is one of the most environmentally hazardous greenhouse gases.

[Gastric rupture as a complication of anorexia nervosa].

Background: Anorexia nervosa may cause several gastro-intestinal complications.

Case Description: A 21-year-old woman presented herself with abdominal pain and vomiting a day after her first binge-eating episode. In her recent history she had lost 40 kg in weight and her BMI was 15 at presentation.

Intramolecular hole-transfer in protonated anthracene.

Excitation spectra of protonated and deuteronated anthracene are obtained by triple-resonance dissociation spectroscopy. Very cold cations, protonated/deuteronated exclusively at the 9-position, are generated from two-colour two-photon threshold ionisation of 9-dihydroanthracenyl radicals (CH). The excitation spectra reveal rich structure, not resolved in previous studies, that is assigned based on anharmonic and Herzberg-Teller coupling calculations.

Photophysical oxidation of HCHO produces HO radicals.

Formaldehyde, HCHO, is the highest-volume carbonyl in the atmosphere. It absorbs sunlight at wavelengths shorter than 330 nm and photolyses to form H and HCO radicals, which then react with O to form HO. Here we show HCHO has an additional HO formation pathway.

POPTARTS: A New Method to Determine Quantum Yields in a Molecular Beam.

A new technique is reported to determine absolute photodissociation quantum yields, ϕ, in a molecular beam. The technique relies on a molecule having two available product channels, where a species in channel A can be converted photolytically to a species in channel B. The relative decrease in the species from channel A and the relative increase in species from B provide a direct measure of the relative product yield of each channel, with no external calibration required.

Diabatic Valence-Hole States in the C Molecule: "Putting Humpty Dumpty Together Again".

Despite the long history of spectroscopic studies of the C molecule, fundamental questions about its chemical bonding are still being hotly debated. The complex electronic structure of C is a consequence of its dense manifold of near-degenerate, low-lying electronic states. A global multi-state diabatic model is proposed here to disentangle the numerous configuration interactions that occur within four symmetry manifolds of excited states of C (Π, Π, Σ , and Σ ).

PAH Growth in Flames and Space: Formation of the Phenalenyl Radical.

Polycyclic aromatic hydrocarbons (PAHs) are intermediates in the formation of soot particles and interstellar grains. However, their formation mechanisms in combustion and interstellar environments are not fully understood. The production of tricyclic PAHs and, in particular, the conversion of a PAH containing a five-membered ring to one with a six-membered ring are of interest to explain PAH abundances in combustion processes.

Photodissociation of dicarbon: How nature breaks an unusual multiple bond.

The dicarbon molecule (C) is found in flames, comets, stars, and the diffuse interstellar medium. In comets, it is responsible for the green color of the coma, but it is not found in the tail. It has long been held to photodissociate in sunlight with a lifetime precluding observation in the tail, but the mechanism was not known.

Photodissociation dynamics of CFCHO: C-C bond cleavage.

The photodissociation dynamics of jet-cooled trifluoroacetaldehyde (CFCHO) into radical products, CF + HCO, was explored using velocity mapped ion imaging over the wavelength range 297.5 nm ≤λ≤ 342.8 nm (33 613-29 172 cm) covering the entire section of the absorption spectrum accessible with solar actinic wavelengths at the ground level.

General hospital specialists' attitudes toward psychiatry: a cross-sectional survey in seven countries.

Objective: Psychiatric comorbidities are common in physical illness and significantly affect health outcomes. Attitudes of general hospital doctors toward psychiatry are important as they influence referral patterns and quality of care. Little is known about these attitudes and their cultural correlates.

Rotational resonances in the HCO roaming reaction are revealed by detailed correlations.

Since its discovery 16 years ago, roaming has become a ubiquitous mechanism in molecular photochemistry. Its general features are now understood, but little detail is known about how the potential energy surface (PES) determines reaction outcomes. We performed detailed experiments on formaldehyde (HCO) photodissociation and determined fully correlated quantum state distributions of the molecular hydrogen and carbon monoxide products.

A qualitative study on factors influencing the situational and contextual motivation of medical specialists.

Objectives: The aim was to investigate which factors influence the situational motivation of medical specialists and how situational and contextual motivation affect one another.

Methods: A qualitative design was used, and a constructivist approach was adopted with the Self-Determination Theory of motivation as a framework. Twenty-two medical specialists from three medical centers in the Netherlands were recruited through convenience, snowball and purposive sampling and observed for two days each.

Quantum-Induced Symmetry Breaking in the Deuterated Dihydroanthracenyl Radical.

The hydrogen-atom adduct with anthracene, 9-dihydroanthracenyl radical (CH), and its deuterated analogue have been identified by laser spectroscopy coupled to time-of-flight mass spectrometry, supported by time-dependent density functional theory calculations. The electronic spectrum of 9-dihydroanthracenyl radical exhibits an origin band at 19115 cm and its ionization energy was determined to be 6.346(1) eV.

Dynamics and quantum yields of H + CHCO as a primary photolysis channel in CHCHO.

The first experimental observation of the primary photochemical channel of acetaldehyde leading to the formation of ketene (CHCO) and hydrogen (H) molecular products is reported. Acetaldehyde (CHCHO) was photolysed in a molecular beam at 305.6 nm and the resulting H product characterized using velocity-map ion (VMI) imaging.

Jet-Cooled Spectroscopy of ortho-Hydroxycyclohexadienyl Radicals.

The electronic spectra of the ortho-hydroxycyclohexadienyl radical have been observed following the supersonic expansion of the electric discharge products of phenol and water. Hydrogen atoms, split from water, add to the phenol ring at the ortho position, generating syn and anti rotamers with respect to the hydroxyl group. The D ← D transitions were recorded by resonance-enhanced multiphoton ionization spectroscopy.

[Valproic acid toxicity due to misinterpretation of plasma levels: increase in unbound fraction caused by hypoalbuminaemia and renal dysfunction].

Background: Valproic acid is one of the most widely prescribed drugs for the treatment of epilepsy and bipolar disorder. As only the unbound fraction of a medicinal product is pharmacologically active, in some strong protein-bound psychotropic drugs such as valproic acid and phenytoin, a rise in this fraction can lead to severe toxicity.

Case Description: A 65-year-old male with a type 1 bipolar disorder developed a number of neurological symptoms including sluggishness, muscle weakness, difficulty in walking and disorders of micturition after his mood stabiliser was changed to valproic acid.

Interconversion of Methyltropyl and Xylyl Radicals: A Pathway Unavailable to the Benzyl-Tropyl Rearrangement.

The products of an electrical discharge containing toluene are interrogated using resonance-enhanced multiphoton ionization and laser-induced fluorescence spectroscopies. A previously unreported electronic spectrum recorded at m/z = 105, with a putative origin band at 26053 cm, is assigned to methyltropyl radical, which appears to be a major product of the toluene discharge, plausibly arising from CH insertion. All three o-, m-, and p-xylyl isomers are also identified.

The energy dependence of CO(v,J) produced from HCO via the transition state, roaming, and triple fragmentation channels.

The dynamics of CO production from photolysis of HCO have been explored over a 8000 cm energy range (345 nm-266 nm). Two-dimensional ion imaging, which simultaneously measures the speed and angular momentum distribution of a photofragment, was used to characterise the distribution of rotational and translational energy and to quantify the branching fraction of roaming, transition state (TS), and triple fragmentation (3F) pathways. The rotational distribution for the TS channel broadens significantly with increasing energy, while the distribution is relatively constant for the roaming channel.

Photodissociation of acetone from 266 to 312 nm: Dynamics of CH + CHCO channels on the S and T states.

The photodissociation dynamics of acetone (CH)CO, cooled in a molecular beam, have been explored over the wavelength range 266-312 nm. Nascent CH fragments were detected by resonance-enhanced multiphoton ionization, followed by mass-selected ion imaging. For photolysis at λ = 306 nm, the image shows a sharp ring, which, when converted to a translational energy distribution, reveals a narrow Gaussian peak with a maximum at 90% of the available energy.

Hydrogen-atom attack on phenol and toluene is ortho-directed.

The reaction of H + phenol and H/D + toluene has been studied in a supersonic expansion after electric discharge. The (1 + 1') resonance-enhanced multiphoton ionization (REMPI) spectra of the reaction products, at m/z = parent + 1, or parent + 2 amu, were measured by scanning the first (resonance) laser. The resulting spectra are highly structured.

Resonance-Enhanced 2-Photon Ionization Scheme for C2 through a Newly Identified Band System: 4(3)Πg-a(3)Πu.

We report the observation of a new band system of C2, namely, the 4(3)Πg-a(3)Πu system. The bands, observed by resonant 2-photon ionization spectroscopy and time-of-flight mass spectrometry, were identified through a synergy of high-level ab initio computation and double-resonance spectroscopy. Two bands are firmly identified, 1-3 and 0-2, allowing the 4(3)Πg origin to be placed at 51496.

H and D attachment to naphthalene: spectra and thermochemistry of cold gas-phase 1-C10H9 and 1-C10H8D radicals and cations.

Excitation spectra of the 1H-naphthalene (1-C10H9) and 1D-naphthalene (1-C10H8D) radicals, and their cations, are obtained by laser spectroscopy and mass spectrometry of a skimmed free-jet expansion following an electrical discharge. The spectra are assigned on the basis of density functional theory calculations. Isotopic shifts in origin transitions, vibrational frequencies and ionization energies were found to be well reproduced by (time-dependent) density functional theory.

Ionization energies of three resonance-stabilized radicals: cyclohexadienyl (dn, n = 0, 1, 6, 7), 1-phenylpropargyl, and methylcyclohexadienyl.

The ionization energies for three resonance-stabilized radicals are determined: cyclohexadienyl, 1-phenylpropargyl, and methylcyclohexadienyl. The recommended ionization energies are, respectively, 6.820(1), 6.

Excitation spectra of large jet-cooled polycyclic aromatic hydrocarbon radicals: 9-anthracenylmethyl (C15H11) and 1-pyrenylmethyl (C17H11).

The 9-anthracenylmethyl (C15H11) and 1-pyrenylmethyl (C17H11) radicals were identified by a combination of mass-resolved laser spectroscopy of a jet-cooled electrical discharge and quantum chemical methods. The 9-anthracenylmethyl radical was found to exhibit an origin band at 13757 cm(-1), with vibrational structure observed in a1 modes, and even quanta of b1 and a2 modes. The 1-pyrenylmethyl radical was found to exhibit an origin band at 13,417 cm(-1), with a more complex vibrational structure as compared to 9-anthracenylmethyl, on account of its lower symmetry and larger size.

Experimental and theoretical investigation of triple fragmentation in the photodissociation dynamics of H2CO.

The photodissociation dynamics of H2CO molecules at energies bracketing the triple fragmentation threshold were investigated using velocity map ion imaging of the H-atom fragments. An algorithm was developed to model the experimental results as a two-step process: initially barrierless C-H bond fission on the S0 potential energy surface to form H + HCO, followed by secondary fragmentation of those HCO radicals with sufficient internal energy to overcome the small exit channel barrier on the HCO surface to form H + CO. Our model treats the first step using phase space theory (PST) and the second using a combined PST-impulsive model, with a tunneling correction.