Comprehensive characterization of an aspen (<i>Populus tremuloides</i>) leaf litter sample that maintained ice nucleation activity for 48 years

Decaying vegetation was determined to be a potentially important source of atmospheric ice nucleation particles (INPs) in the early 1970s. The bacterium Pseudomonas syringae was the first microorganism with ice nucleation activity (INA) isolated from decaying leaf litter in 1974. However, the ice nucleation characteristics of P. syringae are not compatible with the characteristics of leaf litter-derived INPs since the latter were found to be sub-micron in size, while INA of P. syringae depends on much larger intact bacterial cells. Here we determined the cumulative ice nucleation spectrum and microbial community composition of the historic leaf litter sample 70-S-14 collected in 1970 that conserved INA for 48 years. The majority of the leaf litter-derived INPs were confirmed to be sub-micron in size and to be sensitive to boiling. Culture-independent microbial community analysis only identified Pseudomonas as potential INA. Culture-dependent analysis identified one P. syringae isolate, two isolates of the bacterial species Pantoea ananatis, and one fungal isolate of Mortierella alpina as having INA among 1170 bacterial colonies and 277 fungal isolates, respectively. Both Pa. ananatis and M. alpina are organisms that produce heat-sensitive sub-micron INPs. They are thus both likely sources of the INPs present in sample 70-S-14 and may represent important terrestrial sources of atmospheric INPs, a conclusion that is in line with other recent results obtained in regard to INPs from soil, precipitation, and the atmosphere.</p

Biological Control of Soybean Charcoal Rot Caused by Macrophomina Phaseolina Using Trichoderma harzianum

In this study, the antagonistic effect of Trichoderma harzianum T100 as a potential biocontrol agent against soybean charcoal rot caused by Macrophomina phaseolina were evaluated in in vitro and in vivo conditions. In dual culture tests, isolate T100 inhibited the mycelial growth of pathogen (55.3 %), then over ran and sporulated on the mycelia of M. phaseolina. Microscopic examination of mycelial interaction sites of T. harzianum and M. phaseolina showed that T100 penetrated mycelial cells of pathogen, moved inside and lysed them. Volatile test results indicated that the antagonist inhibited the mycelial growth of pathogen (12.2 %) and decreased the production of microsclerotia in culture media. Data from greenhouse experiments showed that, treatment of soil with T. harzianum T100 resulted in a high percentage of fresh and dry weights of root (57.5 % and 53.6 %) and aerial parts (22.9 % and 11.8 %) of soybean in sterile soil in compared with control. Additionally, reduction of microsclerotial formation on soybean root and steam, microsclerotial coverage, (62.5 %) showed the antagonist ability for initial inoculums reduction in later season

Battery State-of-Charge Approximation for Energy Harvesting Embedded Systems

Abstract Batteries play an integral role in Wireless Sensor Networks as they provide the energy necessary to operate the individual sensor nodes. In order to extend the network’s lifetime, and theoretically permit continuous operation even for systems with high-energy consumption, environmental energy harvesting has attracted much interest. It has been shown that the motes ’ utility can be improved significantly if run-time knowledge of remaining battery capacity is available. In this work, a light-weight and cost effective approach to approximating the bat-tery state-of-charge (SOC) based on voltage measurements is presented. Despite commonly perceived as inferior to other approaches, a performance evaluation shows that SOC approximations with over 95 % accuracy are possible. It is further shown that battery inefficiencies due to e.g., temperature and aging are taken into consideration despite not explicitly modeling these effects. The approach only requires system input voltage measurements, but benefits from optional current and temperature measurements