Anisotropy of the vorticity tensor as a magnetic indicator of aromaticity.

The vorticity vector of the current density JB, induced in the electron cloud of a molecule by a magnetic field B, is defined by VB = ∇×JB. The vorticity tensor is the nonsymmetric second-rank tensor obtained by differentiating the vorticity vector with respect to the components of B, i.e., . It is shown that isosurfaces of its anisotropy can be used as magnetotropicity indicators to detect electron delocalization effects and estimate the degree of aromaticity of cyclic molecules on the magnetic criterion.

Correction: Anisotropy of the vorticity tensor as a magnetic indicator of aromaticity.

Correction for 'Anisotropy of the vorticity tensor as a magnetic indicator of aromaticity' by S. Pelloni et al., Phys. Chem. Chem. Phys., 2020, 22, 1299-1305, DOI: .

Electric Dipole-Magnetic Dipole Polarizability and Anapole Magnetizability of Hydrogen Peroxide as Functions of the HOOH Dihedral Angle.

The trace of tensors that account for chiroptical response of the H2O2 molecule is a function of the HO-OH dihedral angle. It vanishes at 0° and 180°, due to the presence of molecular symmetry planes, but also for values in the range 90-100° of this angle, in which the molecule is unquestionably chiral. Such an atypical effect is caused by counterbalancing contributions of diagonal tensor components with nearly maximal magnitude but opposite sign, determined by electron flow in open or closed helical paths, and associated with induced electric and magnetic dipole moments and anapole moments. For values of dihedral angle external to the 90-100° interval, the helical paths become smaller in size, thus reducing the amount of cancellation among diagonal components. Shrinking of helical paths determines the appearance of extremum values of tensor traces approximately at 50° and 140° dihedral angles.

Magnetizabilities of diatomic and linear triatomic molecules in a time-independent nonuniform magnetic field.

The theory of response of a molecule in the presence of a static nonuniform magnetic field with uniform gradient is reviewed and extended. Induced magnetic dipole, quadrupole, and anapole moments are expressed via multipole magnetic susceptibilities. Dependence of response properties on the origin of the coordinate system with respect to which they are defined is investigated. Relationships describing the change of multipole and anapole susceptibilities in a translation of the reference system are reported. For a single molecule, two quantities are invariant and, in principle, experimentally measurable, that is, the induced magnetic dipole and the interaction energy. The trace of a second-rank anapole susceptibility, related to a pseudoscalar obtained by spatial averaging of the dipole-quadrupole susceptibility, of different sign for D and L enantiomeric systems, is origin independent. Therefore, in an isotropic chiral medium a homogeneous magnetic field induces an electronic anapole, having the same magnitude but opposite sign for two enantiomorphs. Calculations have been carried out for a set of diatomic and linear triatomic systems characterized by the presence of magnetic-field induced toroidal electron currents.

Theoretical estimates of the anapole magnetizabilities of C4H4X2 cyclic molecules for X=O, S, Se, and Te.

Calculations have been carried out for C4H4X2 cyclic molecules, with X=O, S, Se, and Te, characterized by the presence of magnetic-field induced toroidal electron currents and associated orbital anapole moments. The orbital anapole induced by a static nonuniform magnetic field B, with uniform curl C=∇×B, is rationalized via a second-rank anapole magnetizability tensor a(αß), defined as minus the second derivative of the second-order interaction energy with respect to the components C(α) and B(ß). The average anapole magnetizability a̅ equals -χ̅, the pseudoscalar obtained by spatial averaging of the dipole-quadrupole magnetizability χ(α,ßγ). It has different sign for D and L enantiomeric systems and can therefore be used for chiral discrimination. Therefore, in an isotropic chiral medium, a homogeneous magnetic field induces an electronic anapole A(α), having the same magnitude, but opposite sign, for two enantiomorphs.

Could Electronic Anapolar Interactions Drive Enantioselective Syntheses in Strongly Nonuniform Magnetic Fields? A Computational Study.

It is shown that the anapolar interaction of the electrons of a molecule with an external uniform magnetic field B and a uniform curl C = ∇ × B' determines different thermodynamic stabilization of the ground state for the enantiomers and diastereoisomers of a chiral molecule. A series of potential candidates for enantioselective syntheses have been investigated in a computational study via SCF-HF, B3LYP, and various coupled cluster approaches to determine the difference in energy between different enantiomers and diastereoisomers. The calculations show that these differences are very small for B and C presently available but approximately 3 orders of magnitude larger than those determined by parity violation effects. The chances that enantioselective synthesis may be attempted in the future are discussed. Recognition of anapolar interaction in chiral molecules via measurements of an induced magnetic dipole moment in the ordered phase may become possible in the presence of a nonuniform magnetic field with a strong gradient.

Visual recovery after scleral buckling for macula-off retinal detachments: an optical coherence tomography study.

PURPOSE: To assess the postoperative macular reattachment through OCT3 in eyes treated with episcleral surgery due to macula-off rhegmatogenous retinal detachment, as well as to verify if there is a statistically relevant relation between the persistence of a subfoveal detachment and poor postoperative functional recovery. METHODS: Twelve eyes of 12 patients who underwent episcleral surgery due to macula-off rhegmatogenous retinal detachment were enrolled and examined in a prospective study. Exclusion criteria were the following: traumatic retinal detachments, detachment relapses, macular holes, amblyopia, and grade B proliferative vitreoretinopathy or higher. The time period from the onset of subjective symptoms of retinal detachment to retinal surgery ranged from 3 to 7 days. All patients were evaluated in the preoperative and the postoperative period (after 1, 3, and 6 months) through measurement of visual acuity by ETDRS charts, fundus photographs, and macular tomography with OCT3. The postoperative tomography outcomes and the visual acuity were statistically examined using the Mann-Whitney U-test. RESULTS: One month after surgery, despite the macular reattachment assessable ophthalmoscopically and through fundus photographs, the OCT examination showed macular subretinal fluid persistence in 66.6% of cases. After 3 and 6 months, the persistence of such foveal detachment was respectively observed in 41.6% and in 33.3% of cases. Moreover, the macular subretinal fluid persistence in the postoperative period showed a statistically significant relation with poor functional recovery. CONCLUSIONS: Delayed or incomplete visual recovery after episcleral surgery for macula-off retinal detachment may be related to macular subretinal fluid persistence, assessable with tomography and not visible ophthalmoscopically.

Why downfield proton chemical shifts are not reliable aromaticity indicators.

Traces of magnetizability, traces of magnetic shielding at the hydrogen nuclei, and nucleus-independent chemical shift are not reliable aromaticity quantifiers for planar conjugated hydrocarbons. A measure of aromaticity is provided by the out-of-plane tensor components, whose magnitude is influenced by the pi-ring currents. The failure of nucleus-independent chemical shift in this regard was proved for the molecule shown in the abstract graphic, sustaining a diatropic pi-current. The validity of the ring-current model is reaffirmed. [structure: see text]

Ring-current models from the differential Biot-Savart law.

The differential Biot-Savart law provides simple models for the pi ring currents induced in diatropic and paratropic planar conjugated molecules by a perpendicular magnetic field. The model predictions are confirmed by ab initio maps of nuclear magnetic shielding density. The effects on the protons and on the ring carbon atoms from the closest and furthest segments of the current loop are easily interpreted. [structure: see text]

How often does peptic ulcer produce "typical" ulcer symptoms?

Subjective symptoms of 876 hospitalized patients who underwent upper fiber-panendoscopy were evaluated in a prospective study. Ulcer-like symptoms were defined as pain-like discomfort with a regular food-related rhythm. These symptoms indicate ulcer disease with high specificity (96%) but low sensitivity (28%). In particular old patients with second disease rarely have ulcer-like symptoms. In spite of their high specificity, however, ulcer-like symptoms are not proof of active ulceration. Patients with scars but no ulcers may also have ulcer-like symptoms.

Treatment and relapse prophylaxis of duodenal ulcer with pirenzepine and cimetidine.

The effect of pirenzepine and cimetidine on healing, symptoms and relapse rate of duodenal ulcer was studied in a placebo-controlled double-blind trial. Cimetidine (1 g daily) was superior at the beginning of therapy to a low dose of pirenzepine (75 mg daily) and placebo with regard to symptoms. No significant differences in ulcer healing were found between the 3 groups of treatment. The relapse rate after treatment with pirenzepine was lower than after treatment with cimetidine.

Chiral discrimination via nuclear magnetic shielding polarisabilities from NMR spectroscopy: theoretical study of (R(a))-1,3-dimethylallene, (2R)-2-methyloxirane, and (2R)-N-methyloxaziridine.

Three medium-size optically active molecules have been studied to make a guess at candidates suitable for chiral discrimination in an isotropic medium via nuclear magnetic resonance spectroscopy. The criterion for experimental detection is given by the magnitude of the isotropic part of nuclear magnetic shielding polarisability tensors, related to a pseudoscalar of opposite sign for the two enantiomers. The pseudoscalar shielding polarisability at the (17)O nucleus in N-methyloxaziridine, calculated at the Hartree-Fock level, is approximately 7.8 x10(-)(17) mV(-)(1). To obtain an experimentally observable magnetic field induced at the (17)O nucleus in N-methyloxaziridine, electric fields as large as approximately 10(7) - 10(8) Vm(-)(1) should be applied to the probe. The molecular electric dipole moment induced by precession of the magnetic dipole of the (17)O nucleus in a magnetic field of 10 T is, in absolute value, approximately 8.8 x 10(-)(42) Cm. The estimated rf-voltage at a resonance circuit is approximately 10 nV. Smaller values have been estimated for N, C, and H nuclei in 1,3-dimethylallene and 2-methyloxirane.

Ring current effects on nuclear magnetic shielding of carbon in the benzene molecule.

The differential Biot-Savart law of classical electrodynamics was applied to develop a ring current model for the magnetic shielding of the carbon nucleus in benzene. It is shown that the local effect of the pi currents, induced by a magnetic field normal to the molecular plane, on the sigmaC out-of-plane shielding tensor component vanishes. However, approximately 10% of sigmaC is due to the shielding contributions from pi current density in the region of the other carbon atoms. Magnetic shielding density maps obtained via quantum mechanical procedures confirm the predictions of the classical model.

[Double neoplasms in larynx and lung]. / Doppelkarzinome in Larynx und Lungen

The incidence of primary malignant tumors in both the larynx and the bronchial system has been studied in the autopsy material of the Institute of Pathology, University of Zurich. In a total of 29,849 autopsies performed from 1960 to 1972, carcinomas of the bronchus were found in 1382 patients (4.6%) and carcinomas of the larynx in 214 patients (0.7%). 17 patients had primary carcinomas in both the larynx and the bronchus. The coexistence of both these carcinomas is about twice as frequent as their calculated chance combination. The importance of appropriate clinical examination of patients with lung or larynx carcinoma is accordingly stressed.

Gardner's syndrome with glandular cysts of the fundic mucosa.

The present study describes a family (mother and son) with Gardner's syndrome. Aside from the classical findings, gastric polyposis was found; histologically glandular cysts of the fundic mucosa were diagnosed. The occurrence of gastric polyps in Gardner's syndrome has recently been described with increasing frequency. These lesions have various histological aspects. A number of authors have noted several cases of Gardner's syndrome with glandular cysts of the fundic mucosa, but to our knowledge this is the first case of familial occurrence.

[Controlled trials of premedication of fiberendoscopy (author's transl)]. / Kontrollierte Studien zur Prämedikation von oberen Fiberendoskopien.

In four controlled studies on 771 consecutive patients we tested the value of premedication before passing a fiberendoscope. Following local anaesthesia of the throat, 10 mgs of diazepam in patients less than 60 years and 5 mgs in those over 60 years quickly injected intravenously caused a sufficient premedication for fiberendoscopy. Premedication with diazepam is better than placebo. We fell that omission of premedication is not justifiable. Flunitrazepam, for premedication, in doses of 1-2 mgs did not prove to be suitable. 20 patients were radiologically controlled for signs of aspiration following premedication and endoskopy. They showed no signs of aspiration.

[Are loss of glistening of normal colour and increased friability normal aspects of the oesophagus in old age? (author's transl)]. / Glanzverlust, Farbveränderungen und erhöhte Lädierbarkeit der Speiseröhre: altersbedingte Normvarianten?

Friability of the esophageal mucosq increases with old age. Old patients without esophageal disease also show loss of glistening and of the normal pink color of the mucosa. These findings on their own are therefore no signs of esophagitis,

[Endoscopic diagnosis of oesophagitis: problems of differentiation from normal (author's transl)]. / Endoskopische Diagnose der Osophagitis Wo liegt die Grenze zum Normalen

The diagnostic significance of endoscopically early signs of oesophagitis in the absence of macroscopic evidence of epithelial abnormalities has been studied prospectively. Changes from the usually observed shininess, pale-pink colour, smooth texture, regular capillaries, sharp Z-line and a decreased mechanical resistance of the mucosa to mechanical damage do not indicate oesophagitis. Nor should one infer gastro-oesophageal reflux from these endoscopic findings. They are presumably ageing changes in the oesophagus.

Phlegmonous gastritis diagnosed by endoscopic snare biopsy.

A case of phlegmonous gastritis, diagnosed for the first time without laparotomy and with spontaneous recovery, is described. The only procedure allowing nonsurgical diagnosis of this disease is endoscopic snare ("jumbo") biopsy of the giant folds in the diseased parts of the stomach. Snare biopsy includes submucosal tissue which is the main site of histological changes in phlegmonous gastritis.