Electron spin resonance of Gd3+ in ceramic PbTio3

The electron spin resonance spectra of Gd3+ in ceramic PbTiO3 and, as a comparison, in powdered Bi3Mg2(NO3)12·24H2O are reported. The interpretation, in terms of crystal field parameters, of the spectrum of the double nitrate is in good agreement with previous single crystal results. It was not possible to interpret the room temperature spectrum of PbTiO3. However, the spectrum of this compound measured above its Curie-temperature (763 K) can be interpreted. This shows that the local crystal field symmetry of a small part of the Gd3+-ions at this temperature is orthorhombic or lower, not-withstanding the cubic lattice symmetry of PbTiO3 under these conditions

The mechanism of the catalytic oxidation of hydrogen sulfide *1: III. An electron spin resonance study of the sulfur catalyzed oxidation of hydrogen sulfide

ESR experiments on the oxidation of hydrogen sulfide were performed in the temperature range 20–150 °C. Alumina, active carbon and molecular sieve zeolite 13X were investigated as catalysts. For zeolite 13X it was demonstrated that the reaction is autocatalytic and that sulfur radicals are the active sites for oxygen chemisorption. The intensity of the sulfur radical ESR signal, which is related to the degree of conversion of these radicals, by oxygen, fits in with an oxidation-reduction mechanism.\ud \ud The sulfur-oxygen radical species, which appear when oxygen is admitted to sulfur radicals, are assigned to sulfur chains containing one or two oxygen atoms at the end of the chain. It is very likely that these sulfur-oxygen radicals are intermediates in the proposed mechanism. The formation of the byproduct SO2 from SxO2 · − at temperatures above 175 °C is also visible in the ESR spectrum.\ud \ud On the basis of the experiments it is concluded that in the mechanism of H2S oxidation on active carbons, carbon radicals do not play an important role

Metagenomic sequencing for surveillance of food- and waterborne viral diseases

A plethora of viruses can be transmitted by the food- and waterborne route. However, their recognition is challenging because of the variety of viruses, heterogeneity of symptoms, the lack of awareness of clinicians, and limited surveillance efforts. Classical food- and waterborne viral disease outbreaks are mainly caused by caliciviruses, but the source of the virus is often not known and the foodborne mode of transmission is difficult to discriminate from human-to-human transmission. Atypical food- and waterborne viral disease can be caused by viruses such as hepatitis A and hepatitis E. In addition, a source of novel emerging viruses with a potential to spread via the food- and waterborne route is the repeated interaction of humans with wildlife. Wildlife-to-human adaptation may give rise to self- limiting outbreaks in some cases, but when fully adjusted to the human host can be devastating. Metagenomic sequencing has been investigated as a promising solution for surveillance purposes as it detects all viruses in a single protocol, delivers additional genomic information for outbreak tracing, and detects novel unknown viruses. Nevertheless, several issues must be addressed to apply metagenomic sequencing in surveillance. First, sample preparation is difficult since the genomic material of viruses is genera