Millimeter-Wave Spectroscopy of Methylfuran Isomers: Local vs. Global Treatments of the Internal Rotation.

Methylfurans are methylated aromatic heterocyclic volatile organic compounds and primary or secondary pollutants in the atmosphere due to their capability to form secondary organic aerosols in presence of atmospheric oxidants. There is therefore a significant interest to monitor these molecules in the gas phase. High resolution spectroscopic studies of methylated furan compounds are generally limited to pure rotational spectroscopy in the vibrational ground state.

Laboratory study of iron isotope fractionation during dissolution of mineral dust and industrial ash in simulated cloud water.

Atmospheric deposition is a key mode of iron (Fe) input to ocean regions where low concentrations of this micronutrient limit marine primary production. Various natural particles (e.g.

Intramolecular H-Bond Dynamics of Catechol Investigated by THz High-Resolution Spectroscopy of Its Low-Frequency Modes.

Catechol is an oxygenated aromatic volatile organic compound and a biogenic precursor of secondary organic aerosols. Monitoring this compound in the gas phase is desirable due to its appreciable reactivity with tropospheric ozone. From a molecular point of view, this molecule is attractive since the two adjacent hydroxy groups can interchangeably act as donor and acceptor in an intramolecular hydrogen bonding due to the tunnelling between two symmetrically equivalent structures.

Characterization of the Observed Electric Field and Molecular Relaxation Times for Millimeter-Wave Chirped Pulse Instrumentation.

In a chirped pulse experiment, the strength of the signal level is proportional to the amplitude of the electric field, which is weaker in the millimeter-wave or submillimeter-wave region than in the microwave region. Experiments in the millimeter region thus require an optimization of the coupling between the source and the molecular system and a method to estimate the amplitude of the electric field as seen by the molecular system. We have developed an analytical model capable of reproducing the coherent transient signals obtained with a millimeter-wave chirped pulse setup operated in a monochromatic pulse mode.

Conformational landscape and inertial defect of methoxyphenol isomers studied by mm-wave spectroscopy and quantum chemistry calculations.

Because methoxyphenols (MP) are emitted in significant quantities during biomass fires and contribute to the secondary organic aerosols formation which impacts the climate, their gas phase monitoring in the atmosphere is crucial and requires accurate rovibrational cross sections determined with a good knowledge of their ground state (GS) and vibrationally excited state (ES) molecular parameters. Therefore, the rotational spectra of the two isomers, 2-MP (guaïacol) and 4-MP (mequinol), have been measured in absorption and in emission at room temperature using a frequency multiplication chain and a mm-wave Fourier transform chirped-pulse spectrometer, respectively. Guided by quantum chemistry calculations, the conformational landscape has been characterised and the observation of only one rotamer in the spectra of 2-MP and 4-MP has been explained.

Full Conformational Landscape of 3-Methoxyphenol Revealed by Room Temperature mm-wave Rotational Spectroscopy Supported by Quantum Chemical Calculations.

Room temperature millimeter-wave rotational spectroscopy supported by high level of theory calculations have been employed to fully characterise the conformational landscape of 3-Methoxyphenol, a semi-volatile polar oxygenated aromatic compound precursor of secondary organic aerosols in the atmosphere arising from biomass combustion. While previous rotationally-resolved spectroscopic studies in the microwave and in the UV domains failed to observe the complete conformational landscape, the 70-330 GHz rotational spectrum measured in this study reveals the ground state rotational signatures of the four stable conformations theoretically predicted. Moreover, rotational transitions in the lowest energy vibrationally excited states were assigned for two conformers.

High resolution study of the ν and ν rovibrational fundamental bands of thionyl chloride: Interplay of an evolutionary algorithm and a line-by-line analysis.

The ν and ν fundamental bands of thionyl chloride (SOCl) were measured in the 420 cm-550 cm region using the FT-far-IR spectrometer exploiting synchrotron radiation on the AILES beamline at SOLEIL. A straightforward line-by-line analysis is complicated by the high congestion of the spectrum due to both the high density of SOCl rovibrational bands and the presence of the ν fundamental band of sulfur dioxide produced by hydrolysis of SOCl with residual water. To overcome this difficulty, our assignment procedure for the main isotopologues SOCl and SOClCl alternates between a direct fit of the spectrum, via a global optimization technique, and a traditional line-by-line analysis.

Ab initio rovibronic states of the thioketenyl radical in its X2Π electronic ground state.

We present an ab initio study of the thioketenyl (HCCS) radical in its degenerate X(2)Π electronic ground state. All rotational and vibrational degrees of freedom are taken into account including the electronic orbital and spin angular momenta. The structure of the rovibronic levels and the nature of the corresponding wave functions show resonances even at very low energies due to strong couplings between the bending, rotation, and spin terms in the Hamiltonian.

Ab initio potential-energy surface and rovibrational states of the HCN-HCl complex.

A four-dimensional intermolecular potential-energy surface has been calculated for the HCN-HCl complex, with the use of the coupled cluster method with single and double excitations and noniterative inclusion of triples. Data for more than 13,000 geometries were represented by an angular expansion in terms of coupled spherical harmonics; the dependence of the expansion coefficients on the intermolecular distance R was described by the reproducing kernel Hilbert space method. The global minimum with De=1565 cm(-1) and Re=7.

Ab initio calculation of the NH(3sigma-)-NH(3sigma-) interaction potentials in the quintet, triplet, and singlet states.

We present the ab initio potential-energy surfaces of the NH-NH complex that correlate with two NH molecules in their 3sigma- electronic ground state. Three distinct potential-energy surfaces, split by exchange interactions, correspond to the coupling of the S(A) = 1 and S(B) = 1 electronic spins of the monomers to dimer states with S = 0, 1, and 2. Exploratory calculations on the quintet (S = 2), triplet (S = 1), and singlet (S = 0) states and their exchange splittings were performed with the valence bond self-consistent-field method that explicitly accounts for the nonorthogonality of the orbitals on different monomers.

Theoretical study of the He-HF+ complex. II. Rovibronic states from coupled diabatic potential energy surfaces.

The bound rovibronic levels of the He-HF+ complex were calculated for total angular momentum J=1/2, 3/2, 5/2, 7/2, and 9/2 with the use of ab initio diabatic intermolecular potentials presented in Paper I and the inclusion of spin-orbit coupling. The character of the rovibronic states was interpreted by a series of calculations with the intermolecular distance R fixed at values ranging from 1.5 to 8.

Analysis of the "Unusual" Vibrational Components of Triply Degenerate Vibrational Mode nu(6) of Mo(CO)(6) Based on the Classical Interpretation of the Effective Rotation-Vibration Hamiltonian.

Rotational structure of the triply degenerate vibrational state nu(6)(F(1u)) of the octahedral molecule Mo(CO)(6) is analyzed qualitatively on the basis of classical mechanics. We show that the energy level redistribution between the vibrational components of nu(6)(F(1u)) occurs due to rotational excitation and is related to the formation of singular points of classical rotational energy surfaces. The singularity is stable under small variations of parameters of the effective rovibrational Hamiltonian.

Aplasia and hypoplasia of the vestibulocochlear nerve: diagnosis with MR imaging.

Purpose: To introduce aplasia or hypoplasia of the vestibulocochlear nerve (VCN) as a possible cause of hearing loss and to identify the magnetic resonance (MR) imaging characteristics of this entity.

Materials And Methods: In seven patients with congenital deafness or unexplained sensorineural hearing loss, MR imaging enabled diagnosis of aplasia or hypoplasia of the VCN. Axial (0.

Inner ear malformations in patients with sensorineural hearing loss: detection with gradient-echo (3DFT-CISS) MRI.

The sensitivity of different MRI sequences in the detection of inner ear malformations in patients presenting with sensorineural hearing loss (SNHL) and/or vertigo was evaluated. We studied 650 patients presenting with SNHL and/or vertigo, clinically not suspected of having inner ear malformations. The sensitivity of T1-weighted, Gd-enhanced T1-weighted and (when available) T2-weighted spin-echo images, and three-dimensional Fourier transformation-constructive interference in steady state (3DFT-CISS) gradient-echo images, to unexpected malformations was assessed.

[Hearing loss following lumbar puncture: case report and literature study].

This report describes a patient with permanent hearing loss after spinal anesthesia. The literature is reviewed, particularly concerning incidence and possible causes. The incidence is surprisingly high and related to the size of the needle.

MRI in craniofacial fibrous dysplasia.

Five patients with biopsy-proven craniofacial fibrous dysplasia underwent MRI with T1- and T2-weighted sequences and a gadolinium-enhanced T1-weighted spin-echo sequence. Low to intermediate signal intensity was usually seen in the largest part of the lesion on both spin-echo sequences, but smaller regions of hyperintensity on T1- and T2-weighted images and intermediate signal intensity throughout a lesion on T1-weighted images were also seen. All lesions enhanced but only two became iso- or hyperintense compared to fat.

[Orbital involvement of sinusitis].

Sinusitis can spread to the orbital tissues. 'Preseptal' soft-tissue bacterial infections are relatively common during childhood and with appropriate antimicrobial therapy they usually resolve quickly. 'Orbital' soft-tissue infections, in contrast, are relatively rare and frequently cause serious morbidity.

Long-term (2-year) isradipine data in the treatment of mild-to-moderate hypertension.

At the end of a short-term (3-month) study of antihypertensive treatment of mild-to-moderate hypertension, 141 of the 200 study patients continued into a 2-year follow-up of isradipine as monotherapy or in combination with other antihypertensive agents. Although all 141 patients completed the first year, only 102 completed the study. Twenty-four patients dropped out: 2 with flushing; 1 each with arrhythmia, edema, angina, and headache; 12 who were noncompliant; 2 with disease unrelated to the study drug; and 4 for reasons unknown.

[Nasal endoscopic approach to sinus diseases].

The endoscopical endonasal surgery is in vogue. Today it has become a functional surgery. A thorough knowledge of the endonasal anatomy is difficult but essential.

[Ototopic agents].

In treating ear disease every otolaryngologist is familiar with topical medications. The choice of the ideal agent for a given clinical situation may be difficult. In order to make this decision more easy, we overlook the composition of ear-drops.

[Mesenchymal chondrosarcoma].

A case is presented of mesenchymal chondrosarcoma. This extremely rare tumor has a characteristic histology. The prognosis is poor.

[The CO2 laser in otorhinolaryngology. Advantages as opposed to conventional surgery and current possibilities].

The future of lasers in medicine in general and in otorhinolaryngology in specific appears to be bright. It's use is very simple, but may not weaken the wakefulness of its user. Skill and experience remain very important.

Vascular tinnitus and arteriovenous meningeal fistula.

With the development of improved angiographic techniques, arteriovenous meningeal fistulas are being recognized more and more as an important cause of vascular tinnitus. Vascular tinnitus is generally considered to be objective and pulse-synchronous. This report concerns three cases of vascular tinnitus due to arteriovenous meningeal fistulas.

[Clear cell tumor of the parotid gland].

An eighty year old female patient consulted for a tumor in the pharyngeal wall and palate. CT showed a big tumor mass, originating from the deep lobe of the parotid gland. Facial function was normal.

[Results of screening for hearing disorders using the Ewing test].

Late developments support that deaf children have an urgent need for rehabilitation and hence for early search for hearing defects. One of the modalities to achieve this goal is mass screening of populations. In Belgium the long established well-baby-clinics provide a commodity for these programs.