Electrochemical Nitrate-to-Ammonia Conversion Enabled by Carbon-Decoration of Ni─GaOOH Synthesized via Plasma-Assisted CO2 Reduction.

The release of nitrates into the environment leads to contaminated soil and water that poses a health risk to humans and animals. Due to the transition to renewable energy-based technologies, an electrochemical approach is an emerging option that can selectively produce valuable ammonia from nitrate sources. However, traditional metal-based electrocatalysts often suffer from low nitrate adsorption that reduces NH3 production rates. Here, a Ni-GaOOH-C/Ga electrocatalyst for electrochemical nitrate conversion into NH3 is synthesized via a low energy atmospheric-pressure plasma process that reduces CO2 into highly dispersed activated carbon on dispersed Ni─GaOOH particles produced from a liquid metal Ga─Ni alloy precursor. Nitrate conversion rates of up to 26.3 µg h-1 mg-1 cat are achieved with good stability of up to 20 h. Critically, the presence of carbon centers is central to improved performance where both Ni─C and NiO─C interfaces act as NO3- adsorption and reduction centers during the reaction. Density functional theory (DFT) calculations indicate that the NiO─C and Ni─C reaction sites reduce the Gibbs free energy required for NO3- reduction to NH3 compared to NiO and Ni. Importantly, catalysts without carbon centers do not produce NH3, emphasizing the unique effects of incorporating carbon nanoparticles into the electrocatalyst.

Cellular and molecular response of human macrophages exposed to Aggregatibacter actinomycetemcomitans leukotoxin.

Aggregatibacter (Actinobacillus) actinomycetemcomitans is a facultative anaerobic gram-negative bacterium associated with severe forms of periodontitis. A leukotoxin, which belongs to the repeats-in-toxin family, is believed to be one of its virulence factors and to have an important role in the bacterium's pathogenicity. This toxin selectively kills human leukocytes by inducing apoptosis and lysis. Here, we report that leukotoxin-induced cell death of macrophages proceeded through a process that differs from the classical characteristics of apoptosis and necrosis. A. actinomycetemcomitans leukotoxin-induced several cellular and molecular mechanisms in human macrophages that led to a specific and excessive pro-inflammatory response with particular secretion of both interleukin (IL)-1ß and IL-18. In addition, this pro-inflammatory cell death was inhibited by oxidized ATP, which indicates involvement of the purinergic receptor P2X(7) in this process. This novel virulence mechanism of the leukotoxin may have an important role in the pathogenic potential of this bacterium and can be a target for future therapeutic agents.

Aeromonas-Acanthamoeba interaction and early shift to a viable but nonculturable state of Aeromonas by Acanthamoeba.

AIMS: To investigate the hypothesis that amoeba may comprise a significant environmental reservoir for Aeromonas, Acanthamoeba-Aeromonas interaction experiments were performed. METHODS AND RESULTS: Acanthamoeba were grown in monoculture and co-cultures with three different species of Aeromonas. Survival, invasion and viable but nonculturable state experiments were performed. We showed that at a low initial bacterial cell density, growth of Aeromonas spp. was inhibited by Acanthamoeba castellanii, while A. castellanii growth was unaffected. In contrast, a high initial bacterial cell density, Aeromonas hydrophila AEW44 and Aeromonas veronii biovar sobria AEW104 suppressed the growth of A. castellanii. Fluorescent and phase-contrast microscopic observations of GFP tagged Aer. hydrophila AEW44 demonstrated that the bacterial cells aggregated on A. castellanii cells after 15 min of incubation and internalized. Aeromonas hydrophila AEW44 cells were found to be actively moving. Interestingly, Aer. hydrophila AEW44 cells shifted more rapidly to a viable but nonculturable form when co-cultured with A. castellanii than in monoculture. CONCLUSIONS: We demonstrated that Aeromonas spp. are able to interact with and to infect the protozoan A. castellanii under laboratory conditions. SIGNIFICANCE AND IMPACT OF THE STUDY: Free-living amoeba might play a role as reservoir for Aeromonas, and thus may increase the transmission of Aeromonas by acting as a vehicle.

THE INTELLECT OF EAST AFRICAN STUDENTS.

The present experiment is intended to confirm my earlier findings, and to sustain the assumption that East African students' structure of mental difficulties is no different from that of students in the West. Seven factors were chosen for this study, each being represented by two Western reference tests. These Factors are: NFT; CFB; CFU; MSI; ESU; CMU and DSU. The battery was administered to two samples of students:-l04 Higher School Certificate boys (HSC) in secondary 5 land 6, and 165 Makerere University College Undergraduates (MUC). Principal components analysis was followed by orthogonal rotation using the Varimax solution. The seven factors were identifiable in both samples, tending to sustain the assumption that. the structure of mental abilities in East African students is similar to that in Western students.