Communication: In search of four-atom chiral metal clusters

A combined study utilizing anion photoelectron spectroscopy and density functional theory was conducted to search for four-atom, chiral, metal, and mostly metal clusters. The clusters considered were AuCoMnBi−/0, AlAuMnO−/0, AgMnOAl−/0, and AuAlPtAg−/0, where the superscripts, −/0, refer to anionic and neutral cluster species, respectively. Based on the agreement of experimentally and theoretically determined values of both electron affinities and vertical detachment energies, the calculated cluster geometries were validated and examined for chirality. Among both anionic and neutral clusters, five structures were identified as beingchiral

Cerebrospinal fluid findings in patients with neurological manifestations in post-COVID-19 syndrome

BACKGROUND: Information on cerebrospinal fluid (CSF) findings in patients with neurological manifestations in post-COVID-19 syndrome is scarce. METHODS: Retrospective evaluation of 84 CSF samples in patients fulfilling post-COVID-19 criteria in two neurological post-COVID-19 outpatient clinics. RESULTS: In 68% of samples, all CSF parameters were normal. The most frequent pathological CSF finding was elevation of total protein (median total protein 33.3 mg/dl [total range 18.5-116.2]) in 20 of 83 (24%) samples. The second most prevalent pathological finding was a blood-CSF barrier dysfunction as measured by elevation of QAlb (median QAlb 4.65 [2.4-13.2]) in 11/84 (13%). Pleocytosis was found in only 5/84 (6%) samples and was mild in all of them. CSF-restricted oligoclonal bands were found in 5/83 (6%) samples. Anti-neuronal autoantibodies in CSF were negative in most cases, whilst 12/68 (18%) samples were positive for anti-myelin autoantibodies in serum. PCR for herpesviridae (HSV-1/-2, VZV, EBV, CMV, HHV6) showed, if at all, only weakly positive results in CSF or EDTA whole blood/plasma. CONCLUSIONS: The majority of samples did not show any pathologies. The most frequent findings were elevation of total protein and blood-CSF barrier dysfunction with no signs of intrathecal inflammation. CSF analysis still keeps its value for exclusion of differential diagnoses

Influence of chlorine substituent positions on the molecular structure and the torsional potentials of dichlorinated biphenyls: R2PI spectra of the first singlet transition and AM1 calculations.

Resonance enhanced two-photon ionization (R2PI) spectra of biphenyl and four dichlorinated biphenyl derivatives (2,6-, 2,2-, 4,4- and 2,4-dichlorobiphenyl) cooled in a supersonic jet expansion have been measured in the region of the S1 ← S0 transition (34 500-36 900 cm-1). The biphenyl derivatives show different torsional angles between the two phenyl rings. The degree of torsion depends on the positions of the substituents due to differing steric and electronic effects on the biaryl chromophore. Furthermore the dihedral angle changes upon electronic excitation. Therefore the electronic spectra of all investigated compounds show a vibronic substructure, dominated by Franck-Condon induced progression of the torsional mode. Nevertheless the four dichlorobiphenyl spectra differ both in energetic locations and vibronic structure. The molecular structures and torsional potentials have been studied by molecular orbital calculations using the AM1 method. The complex structure of the R2PI spectra has been interpreted with the help of these calculations. In addition, the use of R2PI as an analytical tool is demonstrated. R2PI of jet-cooled aromatic molecules provides the possibility of species and isomer selective ionization from a complex mixture. In the case of polychlorinated biphenyls (PCBs) an isomer selective registration of the important toxic (coplanar) PCBs should be possible

A mobile resonance enhanced multiphoton ionisation - time-of-flight mass spectrometer with a novel hybrid laser desorption-/molecular beam ion source for rapid detection of aromatic trace compounds from gas phase and solid samples

A mobile resonance enhanced multiphoton ionisation - time-of-flight mass spectrometer with a novel hybrid laser desorption-/molecular beam ion source for rapid detection of aromatic trace compounds from gas phase and solid samples / R. Zimmermann ... - In: Journal of chromatography. A. 1058. 2004. S. 39-4