Stem embolism vulnerability curve depends on methods used: is there a fifth mechanism of cavitation?

A long-established ecological paradigm predicts a functional relationship determining vulnerability to cavitation: vulnerability increases with vessel hydraulic efficiency and vessel diameter. Even within a species, big vessels cavitate before small ones. Some centrifuge methods for measuring vulnerability are prone to artifacts due to nano-particles seeding early embolism, as the particles are drawn into vessels during measurements. Both the Sperry and Cochard rotors are prone to early cavitation due to nano-particles drawn into long and wide vessels in Robinia pseudoacacia and Quercus acutissima, whereas extraction centrifuge methods produce vulnerability curves more resistant to cavitation. Sufficient nano-particles pass through the stems to seed early embolism in all rotor designs. For several years, people have thought that early embolism is induced by nano-particles present in laboratory water. One new hypothesis is that the origin of nano-particles is from cut-open living cells but a much bigger study including many species is required to confirm this idea. This paper confirms the hypothesis in comparisons between short-vesselled Acer, and long-vesselled Robinia, and Quercus. Our new results and a review of old results justifies bigger study. Hypothetical nano-particles might explain why different methods for measuring vulnerability curves cause different T50 = tensions causing 50% loss of hydraulic conductivity. Hence the hypothesis for future research should be that the open-vessel artifact is consistent with 'long' vessels surrounded by cut open living cells.

Microbial composition in larval water enhances Aedes aegypti development but reduces transmissibility of Zika virus

Arthropod-borne viruses comprise a significant global disease burden. Surveillance and mitigation of arboviruses like Zika virus (ZIKV) require accurate estimates of transmissibility by vector mosquitoes. Although Aedes spp.mosquitoes are established as competent ZIKV vectors, differences in experimental protocols across studies prevent direct comparisons of relative transmissibility. An understudied factor complicating these comparisons is differential environmental microbiota exposures, where most vector competence studies use mosquitoes reared in laboratory tap water, which does not represent the microbial complexity of environmental water where wild larvae develop. We simulated natural larval development by rearing Californian Aedes aegypti with microbes obtained from cemetery headstone water compared to conventional tap water. Ae. aegypti larvae reared in environmental cemetery water pupated 3 days faster and at higher rates. Female adult mosquitoes reared in environmental water were less competent vectors of ZIKV compared to laboratory water-reared Ae. aegypti, as evidenced by significantly reduced infection and transmission rates. Microbiome comparisons of laboratory- and environment-water reared mosquitoes and their rearing water showed significantly higher bacterial diversity in environment water; despite this pattern, corresponding differences in diversity were not consistently detected in adult mosquitoes reared in different water sources. We also detected more significant associations between the microbial composition of adult mosquitoes and whether they ingested a bloodmeal than larval water type. Together, these results highlight the role of transient microbes in the larval environment in modulating vector competence. Laboratory vector competence likely overestimates true transmissibility of arboviruses like ZIKV when conventional laboratory water is used for rearing.

Water Hyacinths (Eichhornia crassipes) – Application for Secondary Wastewater Treatment and Biomass Production

Clean water is one of the most significant challenges for our society. Efficient reuse of effluent water after treatment can becomes an effective solution to the shortage of water resources. The focus of this study is to investigate the use of Eichhornia crassipes plants for post treatment of clarified municipal residential sewage under natural conditions using a small pilot Laboratory Water Hyacinth Clarifier system. Twelve Eichhornia crassipes plants are used to investigate total phosphorus and ammonia nitrogen removal during a 20-day study period under various retention rates. The biomass gain of the Eichhornia crassipes plants was 2.4-fold from the initial weight of 1556.5 g to 3676.7 g. Total phosphorous reduction of 10.64%, 11.83%, 20.93%, 41.66%, 67.12%, and 40.13% for the 1.5, 9.0, 12.0, 24.0, 48.0 h, and 120.0-hour retention times respectively. Ammonia nitrogen removal was between 35.71%, 33.33% for the 1.50 and 9.0-hour retention time and 42.85% for the 12.0 and 24.0-hour retention time. A reduction of 71.43% resulted for the 48.0-hour retention time and an 85.71% reduction for the 120.0-hour retention time. Overall retention time of 24.0 h, 48.0 h and 120 h tend to give best removal rates for both total phosphorus and ammonia nitrogen removal. Factors such as climate, contaminant concentration, retention rate, and weather conditions play an important role for the application of Eichhornia crassipes in a tertiary treatment sequence of MRS.

Experimental and numerical effects of flow hydraulics and pipe geometry on leakage behavior of laboratory water network distribution systems

As the leakage behavior of water distribution network is considered life-threatening and critical issue, so the behavior of water distribution network system is investigated experimentally and numerically under the effect of different positions and flow rates of leakage outlets taking into consideretion the flowhydraulics and pipe geametry. A laboratory model of the real studied water distribution network is constructed. The laboratory water distribution network is horizontal and has 16 loops with total length 30 m and different diameters. The leakage position in the laboratory water distribution network is altered between main, sub-main and branch pipelines with different flow rates. The characteristics of the ideal laboratory water distribution network with no-leakage are studied first. The studied laboratory water distribution network system parameters are solved theoretically using Hardy-Cross method with seven iterations. The studied water distribution network system was simulated using computational fluid dynamics technique Ansys Fluent 18.2. The aim is to modify the ancient water distribution network by sensing the pressure values using dispersed pressure sensors. Also, from the pressure map of the laboratory water distribution network, the leakage position if exist can be localized. Depending on the sensed pressure, the control circuit programmed to close the corresponding solenoid valves. The leakage flow rates are 0.1, 0.25 and 0.4 L/s and changed between the main and sub-main pipes. The maximum pressure drop around 500 pa at the node directly preceding the leakage point at leakage flow rate 0.4 L/s. The performance of the used solenoid valve is simulated using Matlab-Simulink technique. The simulation results show the response to step down control signal is over damped with steady state error 2 % and settling time 0.6 s.