Agaricus bisporus fruit bodies were exposed to different doses (1, 2, 3, and 4 kGy) of electron beam irradiation (EBI), and various physiological changes associated with postharvest deterioration, as well as selected enzymes considered to play a role in senescence, were monitored over a subsequent 16-day storage period at 4 degrees C and 75-85% relative humidity. EBI retarded postharvest mushroom softening and overall increases in malondialdehyde levels were more pronounced in controls compared with those of the irradiated samples. After 10 days of storage, polyphenoloxidase activity in samples irradiated with 1-4 kGy doses was significantly (P<0.05) lower compared to that in control samples. Superoxide dismutase activity generally declined throughout the postharvest storage period in both irradiated and control samples, but no clear correlation between enzyme activity and EBI dosage was evident. Catalase activity decreased more slowly and to a lesser extent in fruit bodies exposed to 1 kGy compared with that in the controls and the other irradiated samples.
Hypsizygus marmoreus fruit bodies were exposed to different doses of (60)Co gamma-irradiation, stored at 4 degrees C and 65-70% relative humidity, and various physiological changes associated with postharvest deterioration, as well as the activities of selected enzymes widely considered to play a role in the process of senescence, were monitored over a subsequent storage period of 25 days. Exposure to 0.8 kGy irradiation was clearly beneficial in maintaining the postharvest appearance of the mushroom sporophores compared to non-irradiated samples and fruit bodies exposed to higher doses (1.2-2.0 kGy) of irradiation. Samples treated with 0.8 kGy also exhibited smaller initial declines in soluble protein, smaller increases in reducing sugar content, and lower levels of malondialdehyde accumulation during the early storage period. Smallest increases in proteinase activity were recorded in samples dosed with 0.8 and 2.0 kGy, and levels of superoxide dismutase were significantly higher in samples exposed to 0.8 kGy compared with non-irradiated controls. Large initial increases in catalase activity were detected in samples irradiated with 0.8, 1.2, and 1.6 kGy and, although enzyme levels gradually decreased in all samples during further storage, residual levels after 25 days were still severalfold higher in irradiated samples compared with controls. The data increase the current understanding of the effects of gamma-irradiation on the biochemical changes associated with postharvest senescence and should lead to more targeted strategies for reducing postharvest quality loss in H. marmoreus and other mushrooms.
Qingjiang River, the second largest tributary of the Yangtze River in Hubei Province, has taken on the important tasks for power generation and flood control in Hubei Province. The Qingjiang River watershed has a subtropical monsoon climate and, as a result, has dramatic diversity in its water resources. Recently, global warming and climate change have seriously affected the Qingjiang watershed's integrated water resources management. In this article, general circulation model (GCM) and watershed hydrological models were applied to analyze the impacts of climate change on future runoff of Qingjiang Watershed. To couple the scale difference between GCM and watershed hydrological models, a statistical downscaling method based on the smooth support vector machine was used to downscale the GCM's large-scale output. With the downscaled precipitation and evaporation, the Xin-anjiang hydrological model and HBV model were applied to predict the future runoff of Qingjiang Watershed under A2 and B2 scenarios. The preformance of the one-way coupling approach in simulating the hydrological impact of climate change in the Qingjiang watershed is evaluated, and the change trend of the future runoff of Qingjiang Watershed under the impacts of climate change is presented and discussed.
An improved method for preventing vortex rope formation and alleviating the associated pressure fluctuations in turbine draft tubes is investigated using baffles in the draft tube to hinder the swirling flow emerging from a Francis turbine runner. A strong swirl produces flow instabilities and pressure fluctuations. Partial load operating conditions at the rated water head and three flow rates are taken into consideration. It is demonstrated using a computational fluid dynamics simulation that this method effectively eliminates the vortex rope, particularly when using four baffles. The amplitude of the pressure pulsation in the draft tube modified with four baffles was 0.42 times that in a traditional draft tube. The baffles were found to reduce the tangential velocity of the flow in the draft tube and consequently hinder the development of the fierce swirling flow. This type of decrease is more significant compared to the gradual decay due to viscous effects of the solid wall in a traditional draft tube. The conclusion was verified by the results of experiments conducted using a novel device. The measured increase in turbine efficiency exceeded 3% at the evaluated partial loading point, indicating improved economic performance of the turbine.
Freshly harvested Hypsizygus marmoreus mushrooms were packaged using different packaging films, and physiological changes associated with postharvest deterioration, together with the activities of selected enzymes thought to play a role in senescence, were monitored during subsequent storage for 16-24 days at 4 degrees C and 65-70% relative humidity. A biaxially oriented polypropylene film (BOPP) maintained the postharvest appearance of the mushrooms most effectively by significantly reducing the incidence of unsightly aerial hyphae on the pileal surface and restricting mushroom softening. These samples also exhibited smaller initial decreases in soluble protein, smaller increases in reducing sugar content, and lower levels of malondialdehyde accumulation during early storage. Smallest increases in proteinase activity were recorded in samples wrapped with BOPP and polyoletin packaging, and superoxide dismutase and polyphenol oxidase levels were significantly higher and lower, respectively, in the former. Choice of packaging can significantly affect postharvest quality loss in H. marmoreus and improve mushroom shelf life.
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