Positron annihilation lifetime spectroscopy (PALS) is sensitive and proved method for material structure investigations. We used it to investigate the influence of different alkali cations on the structure of zeolite precursors in order to understand better the crystallization mechanism of zeolites. Our previous PALS investigations on Li gels show different structural features obtained for differently prepared gels, indicating the importance of the way on which cations are introduced in the gel matrix. These investigations were now extended to gels containing K, Rb and Cs cations, in correlation to their ionic radius and the way of preparation.

The phase transition associated with orbital-ground-state inversion of high-spin Fe2+ in [Fe(H2O)6](ClO4)2 was studied with nuclear resonant forward scattering of synchrotron radiation (SR). The sudden change in the 57Fe2+ quadrupole interaction results in a change of the quantum-beat frequencies. Quantum-beat patterns taken at the phase transition of [Fe(H2O)6](ClO4)2 are in accordance with mainly coherent rather than with incoherent sums of the scattering amplitudes of the high- and low-quadrupole-interaction phases, a fact supporting the real co-existence of the two phases.

The prevalence of sexual dysfunction in schizophrenia patients was investigated as part of this large (n = 7655), prospective, international (27 countries) study. Based on patient reports, sexual dysfunction affected approx. 50% of patients and the prevalence of complaints varied significantly between regions (p < 0.0001). The prevalence of sexual dysfunction, as perceived by psychiatrists, also varied significantly across regions (p < 0.0001). Psychiatrists significantly underestimated the presence of impotence/sexual dysfunction (p < 0.0001) and loss of libido (p < 0.0001), compared to reports from patients. The frequency of sexual dysfunction was significantly higher in patients who had been using prolactin-elevating antipsychotics prior to study entry, compared to those who had been treated with prolactin-sparing antipsychotics (patient reports, p = 0.002; psychiatrist perception, p = 0.0004). This study has shown that the prevalence of sexual dysfunction is high in both male and female patients with schizophrenia and frequently underestimated by psychiatrists. Regional variation is evident in both psychiatrist perceptions and patient reports of sexual dysfunction. Given the importance of sexual function to quality of life and treatment compliance, proactive assessment of sexual function is required to optimize schizophrenia management.

An anomalous spectral doublet attributed to Fe2+ impurity pairs is observed in Mössbauer absorption spectra of 57Fe0.01Zn0.99Se below room temperature. In Mössbauer emission experiments, ZnSe:57Co polycrystal and powder sources exhibit below 45K the nucleogenic Fe1+ valence state born as an after effect of the electron-capture decay of 57Co. Above 8K, the proportion of the nucleogenic Fe1+ decreases under the effect of the thermally activated Fe1+→Fe2+ relaxation. The activation energy is estimated to 0.004eV. While nucleogenic Fe1+ is absent in ZnSe:57Co single crystal spectra, increasing proportions are detected in samples with an enhanced specific surface. The formation model of the nucleogenic Fe1+ is extended to other zinc chalcogenides and a tentative model is developed, which shows the role of the surface electric field in limiting the formation of nucleogenic Fe1+ in well crystallised source samples.

A total of 1032 vocal cord operations have been performed by means of CO2 laser in the Department of Otorhinolaryngology, Head and Neck Surgery of the Semmelweis University of Medicine in Budapest in the past 10 years. There were 687 benign cases and 345 malignant cases of lesions discovered. The procedures were performed under general anesthesia in many instances with jet narcosis--in laryngomicroscopic exposure. The operations were preceded by careful objective diagnostics, such as videolaryngostroboscopy, fiberoscopy, voice analysis, airflow and resistance measurements, while the voice and breathing functions were monitored postoperatively. Our policy in the therapy of the benign lesions was always to use a minimally invasive technique, avoiding damage to the anterior commissure, the vocal ligament and the subglottic space. We have experienced a 3-year survival rate in 87% of the patients with vocal cord carcinomas. According to the results of the past 10 years it is proven that the CO2 laser technique is an efficient method as well in the surgery of the benign and malignant vocal cord lesions, as in the bilateral vocal cord paralysis. Laser surgery might also prevent malignant transformation in precancerous vocal cord diseases.

Positron lifetime measurements were carried out in normal hexane vs. temperature in the range of 12.5–62.5°C. The evaluation of the lifetime spectra indicates the presence of four lifetime components, as published first by Jacobsen et al. An attempt is made to interprete the properties of the longest-living two components in terms of the microscopic structure of the liquid.

A comprehensive review of positron annihilation studies of Cr-Mo-V reactor pressure vessel (RPV) steels (Soviet type 15Kh2MFA) in unirradiated and neutron irradiated states is presented. The influences of lattice defects, impurity atom distribution, irradiation temperature, flux and fluence of fast neutrons on positron annihilation parameters, especially during isochronal annealing, are discussed in terms of the positron trapping model. In contrast to the literature, where irradiation-enhanced Cu precipitates and solute coated microvoids are thought to be major defect types responsible for strengthening and hence embrittling of RPV steels, we suggest irradiation-induced precipitates, i.e. probably carbides, to play this role. Possibilities to probe this model are suggested.

Mössbauer spectra of57Co: LiTaO3 single crystals were recorded in an external longitudinal magnetic field of 6 T at different temperatures between 4.2 K and 150 K. The spectra were taken at two different orientations of the crystallographicc-axis relative to the magnetic field. The line intensities of the Fe3+-subspectra show a temperature dependent anomalous population of the three Kramers doublets of the Fe3+ spinS=5/2 ground state. A relaxation broadening is observed at higher temperatures, which cannot successfully be reproduced within a relaxation model taking into account only the six lowest lying electronic states.

Results on the incorporation, valence and spin states of Fe(Co) in CuO (with reference to similar studies on high temperature superconductors) and coupling of the Fe(Co) moment to the Cu magnetism in CuO are presented. Freshly prepared57Co: CuO shows two quadrupole doublets D1 and D2 withQ.S. of 2.49 and 1.52,I.S. of 0.35 and 0.70 mm/s and relative abundance of 74% and 26%, respectively at room temperature, the abundance being dependent on time in a sample exposed to ambient conditions and reaching 38 to 62% fifteen months after preparation. Below,TN=2251K, a typical combined magnetic-quadrupole interaction pattern is observed with a single saturation magnetic hfs of 25.6 T, central shift of 0.82 mm/s and a single |EQ|=1.62 mm/s at 4.2 K. External magnetic field spectra reveal an antiferromagnetic behaviour of the Fe(Co) ion. Temperature dependence of the magnetic hfs is fitted in the framework of the molecular field approximation allowing different spins and coupling constants for Cu and Fe(Co).

57Fe Mössbauer spectra of a fullyc-axis oriented epitaxial thin film of YBa2(Cu0.9757Fe0.03)3O7, recorded by CEMS, are reported. Spectra taken at different angles between the normal of the film (i.e. thec-axis) and the gamma ray direction show that for two of the three observed quadrupole doublets the main component of the EFG lies in thea−b-plane, for the third doublet it is parallel to thec-axis. The EFG of all three doublets has approximately axial symmetry.

The Fe2+ fraction observed in the Mössbauer emission spectra of57Co:LiNbO3 and57Co:LiTaO3 exhibits both slow electronic relaxation and nonthermal populations of thems sublevels of the5Alg orbital singlet ground state at low temperatures (T<15 K) in high magnetic fields. The relaxation rates depend on temperature and on the angle ϕ between the magnetic field and the crystallographicc-axis.

Mössbauer emission spectra of57Co: LiTaO3 show as a consequence of the nuclear decay anomalous emission line intensities in the subspectra of Fe2+ and Fe3+. Magnetic field and angle dependence of Fe3+ intensities can be explained by taking into account polarization-and crystal-field effects in the excited states. The experimental results for LiTaO3 are in good agreement with theory and previous measurements on LiNbO3.

Samples of the system LiNbO3-Fe2O3 prepared by water quenching and by the double-roller quenching method in the range up to 24 mol% Fe2O3 were investigated by Mössbauer and ESR spectroscopy. In the water quenched samples up to 11 mol% Fe2O3 only the Fe3+ and the Fe2+ valence states could be detected. The Fe2+ concentration decreased with increasing Fe2O3 content. Above 11 mol% Fe2O3 magnetically split Mössbauer spectra indicated the presence of Fe2O3 clusters. The isomer shift values of Fe3+ as a function of Fe2O3 concentration showed jumps at 6 and 11 mol% Fe2O3, whereas no significant changes could be detected in the quadrupole splitting values. The ESR data already exhibited the existence of isolated Fe3+ ions and of clusters with Fe-Fe distances less than 8 Å for the lowest Fe2O3 concentration. The cluster signal intensity increased with increasing Fe2O3 content. The roller quenched samples showed increased Fe2+ concentration as compared to the water quenched samples, which suggests that slow quenching results in iron oxidation and cluster formation. For low Fe2O3 concentrations a valence state change Fe3+⇄Fe2+ can easily be obtained by heat treatments in various atmospheres, whereas for higher Fe2O3 contents (9.8 mol%) precipitations ofα-Fe (in reducing atmosphere) and Fe2O3 (in air) could be observed in addition to the valence state changes of a remaining part of dissolved Fe ions. On the basis of the obtained results a model was suggested for the unusual behaviour of the lattice parameters observed in LiNbO3-Fe2O3.

First 57 Fe Mössbauer spectra of fully c -axis oriented epitaxial thin films of YBa 2 (Cu 0.97 57 Fe 0.03 ) 3 O 7 , recorded by CEMS ( C onversion E lectron M össbauer S pectroscopy), are reported. Spectra taken at different angles between the normal of the film (i.e. the c -axis) and the gamma ray direction show that for two of the three observed quadrupole doublets the main component of the EFG ( e lectric f ield g radient) lies in the a-b -plane, for the third doublet it is parallel to the c -axis.