The flowers of Polemonium caeruleum are protandrous. The nectary is in the form of a rim encircling the ovary. Secreted nectar accumulates in a chamber located at the bottom of the floral tube and is protected by dense staminal hairs. The nectary tissue is not vascularized, but is supplied by vascular strands that occur near the base of the nectary and which directly supply the stamens. Nectar is secreted via modified stomata located on the upper part of the rim, particularly on the adaxial surface. The number of stomata and the volume and sugar concentration of nectar are greater during the female stage than during the male stage. In both stages, however, the nectar is sucrose-dominant. This paper shows that in P. caeruleum the nectar sugars are not a direct product of current photosynthesis, since plastids of nectary cells are devoid of chlorophyll. The main source of sugars in secreted nectar is the phloem sap, together with starch that accumulates in the nectary cells during the male stage and is then rapidly hydrolyzed during the female stage.

Liquid-gas flows in pipelines appear in many industrial processes, e.g. in the nuclear, mining, and oil industry. The gamma-absorption technique is one of the methods that can be successfully applied to study such flows. This paper presents the use of the gamma-absorption method to determine the water-air flow parameters in a horizontal pipeline. Three flow types were studied in this work: plug, transitional plug-bubble, and bubble one. In the research, a radiometric set consisting of two Am-241 sources and two NaI(TI) scintillation detectors have been applied. Based on the analysis of the signals from both scintillation detectors, the gas phase velocity was calculated using the cross-correlation method (CCM). The signal from one detector was used to determine the void fraction and to recognise the flow regime. In the latter case, a Multi-Layer Perceptron-type artificial neural network (ANN) was applied. To reduce the number of signal features, the principal component analysis (PCA) was used. The expanded uncertainties of gas velocity and void fraction obtained for the flow types studied in this paper did not exceed 4.3% and 7.4% respectively. All three types of analyzed flows were recognised with 100% accuracy. Results of the experiments confirm the usefulness of the gamma-ray absorption method in combination with radiometric signal analysis by CCM and ANN with PCA for comprehensive analysis of liquid-gas flow in the pipeline.