Synthesis and thermal stability of ZrO2@SiO2 core–shell submicron particles

ZrO₂@SiO₂ core–shell submicron particles are promising candidates for the development of advanced optical materials. Here, submicron zirconia particles were synthesized using a modified sol–gel method and pre-calcined at 400 °C. Silica shells were grown on these particles (average size: ∼270 nm) with well-defined thicknesses (26 to 61 nm) using a seeded-growth Stöber approach. To study the thermal stability of bare ZrO₂ cores and ZrO₂@SiO₂ core–shell particles they were calcined at 450 to 1200 °C. After heat treatments, the particles were characterized by SEM, TEM, STEM, cross-sectional EDX mapping, and XRD. The non-encapsulated, bare ZrO₂ particles predominantly transitioned to the tetragonal phase after pre-calcination at 400 °C. Increasing the temperature to 600 °C transformed them to monoclinic. Finally, grain coarsening destroyed the spheroidal particle shape after heating to 800 °C. In striking contrast, SiO₂-encapsulation significantly inhibited grain growth and the t → m transition progressed considerably only after heating to 1000 °C, whereupon the particle shape, with a smooth silica shell, remained stable. Particle disintegration was observed after heating to 1200 °C. Thus, ZrO₂@SiO₂ core–shell particles are suited for high-temperature applications up to ∼1000 °C. Different mechanisms are considered to explain the markedly enhanced stability of ZrO₂@SiO₂ core–shell particles.

Silica encapsulation dramatically enhances the thermal stability of zirconia submicron particles by grain growth inhibition and tetragonal phase stabilization.     

TNM-classification of carcinomas of the oral cavity-efficacy of clinically available data (TN).

Using adequate number of cases, the influence of the spread of primary tumour and the degree of regional metastasis on prognosis were investigated. Assuming a practicable classification as a prerequisite for clinico-therapeutic cancer research, experience has shown that the assessment of the spread of primary tumour alone does not suffice for the establishment of comparable homogenous data. The investigation on the importance of the degree of regional metastasis has shown, above all, that the percentage of N3-metastasis within the T-groups contributes essentially to the fact that these show a marked difference in their prognosis. It would therefore appear necessary also to examine the importance of other clinically accessible data in the assessment of prognosis. Only then could we be in a position to judge whether, and to what extent a clinically practicable classification and integration into special groups is possible on the basis of clinically available data. The inclusion of more clinics in the joint investigation is encouraged.     

Klinisch-experimentelle Untersuchungen zur Lungenfunktionsprüfung mit einem Thermistor als Atemstromrezeptor

Lung - Bei insgesamt 557 gesunden und lungenkranken Probanden wurde eine Vergleichsmessung von forcierter exspiratorischer Vitalkapazität (FVC), forciertem exspiratorischem Volumen in der...     

Wirkung von glukokortikosteroiden bei der experimentellen inhalation von stickstoffdioxid (NO2 )

Zusammenfassung 10 gesunde männliche Probanden im Alter zwischen 20 und 38 Jahren (9 Nichtraucher, 2 Raucher) wurden in einer Klimakammer unter konstanten Temperatur- und Feuchtebedingungen über 2 h gegenüber 5 bzw. 10 ppm NO₂ exponiert; daneben lief ein Kontrollversuch ohne Schadgasbelastung. In den verschiedenen Versuchsserien wurde gleichzeitig bzw. vorher ein Glukokortikosteroid per inhalationem oder intraven6s verabreicht. ErfaBt wurden atemmechanische Größen wie die Strömungswiderstände in den Atemwegen (R_t) und das thorakale Gasvolumen (TGV) und Größen des respiratorischen Gasaustausches wie der arterielle Sauerstoffpartialdruck (PaO₂).Wesentliche Ergebnisse dieser unter kontrollierten Laborbedingungen durchgeführten Untersuchung sind, daß die lokale Applikation von 9 mg Dexamethason-21-isonicotinat per inhalationem bzw. die intravenöse Applikation von 40 mg 6-Methylprednisolon-hemisuccinat die NO₂-Wirkung auf die Strömungswiderstände in den Atemwegen und den respiratorischen Gasaustausch im Mittel verhindert.Danach erscheint die kombinierte lokale and parenterale intensiv-therapeutische Behandlung von Reizgasvergiftungen mit Glukokortikosteroiden sinnvoll.     

Inhibitor development after changing FVIII/IX products in patients with haemophilia

The retrospective observational study surveys the relationship between development of inhibitors in the treatment of haemophilia patients and risk factors such as changing FVIII products. A total of 119 patients were included in this study, 198 changes of FVIII products were evaluated. Results: During the observation period of 12 months none of the patients developed an inhibitor, which was temporally associated with a change of FVIII products. A frequent change of FVIII products didn't lead to an increase in inhibitor risk. The change between plasmatic and recombinant preparations could not be confirmed as a risk factor. Furthermore, no correlation between treatment regimens, severity, patient age and comorbidities of the patients could be found.     

Should the exit of the artificial abutment tooth be positioned in the region of the attached gingiva?

The necessity of an area of attached gingiva around penetrating implants was examined in 26 patients. It was demonstrated that plaque corneal in the major factor in avoiding inflammatory reactions.