Combatting cyanobacteria with hydrogen peroxide: a laboratory study on the consequences for phytoplankton community and diversity

Experiments with different phytoplankton densities in lake samples showed that a high biomass increases the rate of hydrogen peroxide (HP) degradation and decreases the effectiveness of HP in the selective suppression of dominant cyanobacteria. However, selective application of HP requires usage of low doses only, accordingly this defines the limits for use in lake mitigation. To acquire insight into the impact of HP on other phytoplankton species, we have followed the succession of three phytoplankton groups in lake samples that were treated with different concentrations of HP using a taxa-specific fluorescence emission test. This fast assay reports relatively well on coarse changes in the phytoplankton community; the measured data and the counts from microscopical analysis of the phytoplankton matched quite well. The test was used to pursue HP application in a Planktothrix agardhii-dominated lake sample and displayed a promising shift in the phytoplankton community in only a few weeks. From a low-diversity community, a change to a status with a significantly higher diversity and increased abundance of eukaryotic phytoplankton species was established. Experiments in which treated samples were re-inoculated with original P. agardhii-rich lake water demonstrated prolonged suppression of cyanobacteria, and displayed a remarkable stability of the newly developed post-HP treatment state of the phytoplankton community

Branched Poly(ethylene imine)s as Anti‐algal and Anti‐cyanobacterial Agents with Selective Flocculation Behavior to Cyanobacteria over Algae

Poly(ethylene imine)s (PEIs) have been widely studied for biomedical applications, including antimicrobial agents against potential human pathogens. The interactions of branched PEIs (B‐PEIs) with environmentally relevant microorganisms whose uncontrolled growth in natural or engineered environments causes health, economic, and technical issues in many sectors of water management are studied. B‐PEIs are shown to be potent antimicrobials effective in controlling the growth of environmentally relevant algae and cyanobacteria with dual‐functionality and selectivity. Not only did they effectively inhibit growth of both algae and cyanobacteria, mostly without causing cell death (static activity), but they also selectively flocculated cyanobacteria over algae. Thus, unmodified B‐PEIs provide a cost‐effective and chemically facile framework for the further development of effective and selective antimicrobial agents useful for control of growth and separation of algae and cyanobacteria in natural or engineered environments.Poly(ethylene imine)s (B‐PEIs) are shown as effective antimicrobial agents against environmentally relevant microorganisms (algae CR – Chlamydomonas reinhardtii, cyanobacterium SE – Synechococcus elongatus). B‐PEIs have dual‐functionalities and can 1) inhibit growth of both algae and cyanobacteria and 2) selectively flocculate cyanobacteria over algae. These molecules provide a cost‐effective and chemically facile framework for the further development of selective anti‐algal and anti‐cyanobacterial agents.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146449/1/mabi201800187_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146449/2/mabi201800187.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146449/3/mabi201800187-sup-0001-SupMat.pd

Model of a Monopulse Radar Tracking System for Student Laboratory

Development, construction and testing of a student laboratory model of the radar system that can be used for monopulse tracking is described. The laboratory model is simple and can be assembled from the existing equipment while the missing parts can be manufactured in a basically equipped RF electronics workshop. The laboratory model is used for student laboratory exercises as a part of a basic course on radar systems. The system is based on a Σ-Δ hybrid for processing signals obtained from two antennas. The composition of the model is described. Student exercises and measurements on the model are proposed. Alternative instruments which can be used in the model are considered. Possible improvements of the model are discussed

Experimental Research of Corrosion Effects on Steel Bridges

Abstract Bridges are significant elements of the transport infrastructure, so they should be in operation throughout the whole design life. Therefore, it is necessary to know the main causes of damages and failures of the bridges. The corrosion of structural steel caused by atmospheric influences as well as the bridge exploitation cause a cross-sectional reduction of structural elements and, consequently, a decrease of the resistance of steel bridge members. The article deals with corrosion and its impact on steel bridge elements in order to use this data for developing actual corrosion model appropriate for design of structures on durability.</jats:p

Model of a Monopulse Radar Tracking System for Student Laboratory

Development, construction and testing of a student laboratory model of the radar system that can be used for monopulse tracking is described. The laboratory model is simple and can be assembled from the existing equipment while the missing parts can be manufactured in a basically equipped RF electronics workshop. The laboratory model is used for student laboratory exercises as a part of a basic course on radar systems. The system is based on a Σ-Δ hybrid for processing signals obtained from two antennas. The composition of the model is described. Student exercises and measurements on the model are proposed. Alternative instruments which can be used in the model are considered. Possible improvements of the model are discussed