The swimming characteristics of gyrotactic microorganisms are significant to understand the ecological activities in lakes, rivers and oceans. The swimming velocity of a typical motile microorganism, Chlamydomonas reinhardtii, was measured for both still water and low-Reynolds-number flow, based on a microfluidic system. Results show that the swimming speed is subject to Gaussian distribution for the still water, and corresponding mean swimming speed is 41 μm/s. The streamwise mean swimming velocity, 35 μm/s, in the moving water is slightly less than that in the still water. It is also shown that the swimming direction in the horizontal plane is dominated by cell randomness for the still water, and 80% of the cells are aligned with the ambient flow when the flow velocity exceeds 333 μm/s. The standard deviation of swimming direction and the percent of swimming direction in the streamwise direction can reach a stable status with the increase of the flow velocity.

Sustainable food production is one of the major challenges of the twenty-first century in the era of global environmental problems such as climate change, increasing population and natural resource degradation including soil degradation and biodiversity loss. Climate change is among the greatest threats to agricultural systems. Green Revolution though multiplied agricultural production several folds but at the huge environmental cost including climate change. It jeopardized the ecological integrity of agroecosystems by intensive use of fossil fuels, natural resources, agrochemicals and machinery. Moreover, it threatened the age-old traditional agricultural practices. Agriculture is one of the largest sectors that sustain livelihood to maximum number of people and contribute to climate change. Therefore, a climate-smart approach to sustainable food production is the need of hour. Traditional agriculture is getting increased attention worldwide in context of sustainable food production in changing climate. The present article advocates traditional agriculture as a climate-smart approach for the sustainable food production and also deliberates the correlation between climate change and agriculture.

China has promised to optimize its energy structure and reduce its CO₂ emission in the 13th Five-Year Plan. To track the energy structure, the conversions, efficiencies, end consumptions of total energy and coal and the whole CO₂ emission status, the energy flow, coal flow and CO₂ flow in 2015 were, respectively, drawn at the national level based on Sankey diagrams. Besides, each provincial fossil fuel structure, CO₂ structure and CO₂ intensity were calculated and plotted. It is mainly found that China’s energy structure consisted of 69.2% of coal, 19.9% of oil, 6.3% of natural gas and 4.7% of non-fossil energy, where 45.5% of energy was consumed by industry and 23.9% by losses and statistical difference; coal was distributed to industry (55.6%), etc., with a utilization rate of 70.1%; and CO₂ were derived from coal (84.7%), oil (11.1%) and natural gas (4.2%), of which 39.0% was released through the process of thermal power generation and 19.4% by industry. The structures of fossil fuels and their CO₂ emissions together with the evolution of CO₂ intensity at the provincial level and the regional level were also given. Besides, two pieces of policy implications were proposed to provide the government with reference.

A wide variety of substances and agents are released into the atmosphere due to anthropogenic activities. Higher levels of such entities have given rise to four major environmental problems: air, light and noise pollution and global warming, all of which severely affect birds and other animals. These four issues have been overlooked, although climate change is receiving increasing attention. The four challenges often occur simultaneously and are likely to exert composite impacts. Most studies have focused on the effects of a specific problem at a particular time and have never taken into account their cumulative consequences. This review tries to address this shortcoming. It aims to evaluate the composite impacts of the problems on flying birds beyond an understanding of their individual impacts. The review initially sheds light on the individual impacts based on existing scientific literature. Composite impacts were then estimated by assigning suitable scores to the literature to convert it into empirical data. Scores were then analysed. Through this assessment, it was found that the health of birds is highly vulnerable to the composite effects of the problems. Additionally, statistical analysis revealed that the effects of all problems on different aspects of avian biology are likely to be magnified simultaneously in the future. Thus, the impact of these problems on birds should not be neglected, and further studies should be conducted to understand their mechanisms.

Hydrogen (H₂) produced from biological methods is a potential option to meet the growing clean energy needs. The present study aimed to produce biohydrogen by dark fermentation from nuisance aquatic weed, Eichhornia crassipes, using facultative anaerobic bacteria. A total of 12 bacterial strains were isolated from different wastewater sources and were screened for the potential of H₂ production using glucose as carbon source. Ten strains showed the H₂-producing potential and were identified up to the generic level by biochemical tests. Two strains with higher H₂ production were sequenced using PCR technique and identified as Proteus mirabilis and Pseudomonas aeruginosa and selected for the studies with E. crassipes as the substrate. It was found that P. aeruginosa could produce 19.54 ± 0.03% of H₂ from 2% acid (H₂SO₄) treated substrate which was comparatively higher than that of 4 and 8% treatments. P. mirabilis also yielded better results of 5.42 ± 0.02% H₂ f or 2% acid (H₂SO₄) treated substrate than 4 and 8% treatments. In total, 33.52 ± 0.04% of H₂ was produced by P. aeruginosa for the substrate treated with 2% alkali (NaOH). It was noted that with respect to P. mirabilis 4% alkali treated substrate yielded a higher percentage of H₂ (20.23 ± 0.03%) compared to the other two concentrations. The results indicate that alkali treated substrate produced comparatively higher amount of H₂ than that of acid treated substrates. Regarding efficiency, P. aeruginosa was found to be more competent than P. mirabilis.