Die Fluoreszenz von Festkörpern und Flüssigkeiten ist ein weitläufig bekanntes Phänomen, das unter anderem auch im Alltag beobachtet werden kann. In diesem Versuch wird gezeigt, dass auch Stoffe in ...der Gasphase zu einer Fluoreszenz angeregt werden können - am Beispiel von gasförmigen Iod. Diese, durch grünes Laserlicht induzierte faszinierende Fluoreszenzentstehung sowie deren -löschung, können dabei anhand eines didaktisch angepassten Energiestufenmodell im fortgeschrittenen Chemieunterricht anschaulich erarbeitet werden. Darüber hinaus ermöglicht das Experiment viele Anknüpfungspunkte zu den grundlegenden Themen des Chemie- und Physikunterrichts wie Absorption, Emission, Strahlungs- sowie Energieübergänge.
The fluorescence of solids and liquids is a well-known phenomenon, also in everyday life. Within this experiment, the fluorescence of a substance in the gaseous phase is demonstrated by the example of gaseous iodine. In order to explain this fascinating observation, induced by green laser light, as well as its quenching in the presence of nitrogen, a didactically adjusted energy stage model is presented. This model is suitable for advanced chemistry class. In addition, the experiment offers several links to fundamental topics of chemistry and physics education, such as absorption, emission, and radiation and energy transitions.
In recent years, with the unremitting advancement of higher education reform, academics have been experiencing stress associated with conducting scientific research. In this study focusing on ...university teachers in China, we adopted a stepwise regression method and reviewed related literature to construct a mechanism of academic stress and occupational burnout. Specifically, we tested job satisfaction and relative deprivation as mediating and moderating variables and conducted empirical research on 1239 teachers from 15 universities in eastern, central, and western China. Our findings show that: (1) academic stress has a significant positive effect on occupational burnout; (2) job satisfaction has a partial role as the intermediary agent between academic stress and occupational burnout; and (3) relative deprivation positively moderates the relationship between academic stress and job satisfaction, indicating that teachers in universities and colleges are also affected by relative deprivation and the perception of inequity. These findings have significant value in the management of higher education and academic research.
This article introduces the new family of living radical polymerizations with germanium (Ge), tin (Sn), phosphorus (P), and nitrogen (N) catalysts which we recently developed. The polymerizations are ...based on a new reversible activation mechanism, Reversible chain Transfer (RT) catalysis. Low-polydispersity polymers are obtained in the homopolymerizations and random and block copolymerizations of styrene, methyl methacrylate, and functional methacrylates. The background, performance, and kinetic features of the polymerizations are described. Attractive features of the catalysts include their high reactivity, low toxicity (Ge, P, and N), low cost (P and N), and ease of handling (robustness).
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The corrosion and inhibition behaviors of mild steel in aerated sulphuric acid in the presence of propargyl alcohol (PA) and potassium iodide (KI) were investigated using electrochemical methods. It ...was found that the inhibition efficiency increased with PA concentration, but the potential of unpolarizability (
E
u), which indicates the commencement of desorption of adsorbed propargyl alcohol on the electrode, remained unchanged with increasing PA concentration. The addition of potassium iodide in the solution increased the value of
E
u. A synergistic effect was observed between KI and PA with an optimum mass ratio of PA/ KI=1/1. The experimental results suggest that the presence of iodide ions in the solutions stabilized the adsorption of PA molecules on the metal surfaces and, therefore, improved the inhibition efficiency of PA. In the solutions containing propargyl alcohol (PA), the
E
u values remained unchanged with increasing immersion times, indicating that there was less possibility of polymerization of PA molecules. An adsorption mechanism was favored for the inhibition of PA.
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