A review of air filtration technologies for sustainable and healthy building ventilation

Urbanization increased population density in cities and consequently leads to severe indoor air pollution. As a result of these trends, the issue of sustainable and healthy indoor environment has received increasing attention. Various air filtration techniques have been adopted to optimize indoor air quality. Air filtration technique can remove air pollutants and effectively alleviate the deterioration of indoor air quality. This paper presents a comprehensive review on the synergistic effect of different air purification technologies, air filtration theory, materials and standards. It evaluated different air filtration technologies by considering factors such as air quality improvement, filtering performance, energy and economic behaviour, thermal comfort and acoustic impact. Current research development of air filtration technologies along with their advantages, limitations and challenges are discussed. This paper aims to drive the future of air filtration technology research and development in achieving sustainable and healthy building ventilation

The Effects of Hydrogen Peroxide on the Circadian Rhythms of Microcystis aeruginosa

Background: The cyanobacterium Microcystis aeruginosa is one of the principal bloom-forming cyanobacteria present in a wide range of freshwater ecosystems. M. aeruginosa produces cyanotoxins, which can harm human and animal health. Many metabolic pathways in M. aeruginosa, including photosynthesis and microcystin synthesis, are controlled by its circadian rhythms. However, whether xenobiotics affect the cyanobacterial circadian system and change its growth, physiology and biochemistry is unknown. We used real-time PCR to study the effect of hydrogen peroxide (H2O2) on the expression of clock genes and some circadian genes in M. aeruginosa during the light/dark (LD) cycle. Results: The results revealed that H 2O 2 changes the expression patterns of clock genes (kaiA, kaiB, kaiC and sasA) and significantly decreases the transcript levels of kaiB, kaiC and sasA. H2O2 treatment also decreased the transcription of circadian genes, such as photosynthesis-related genes (psaB, psbD1 and rbcL) and microcystin-related genes (mcyA, mcyD and mcyH), and changed their circadian expression patterns. Moreover, the physiological functions of M. aeruginosa, including its growth and microcystin synthesis, were greatly influenced by H 2O 2 treatment during LD. These results indicate that changes in the cyanobacterial circadian system can affect its physiological and metabolic pathways. Conclusion: Our findings show that a xenobiotic can change the circadian expression patterns of its clock genes t

Scheduling multi–mode resource–constrained tasks of automated guided vehicles with an improved particle swarm optimization algorithm

Abstract A modified particle swarm optimization (PSO) approach is presented for the multi‐mode resource‐constrained scheduling problem of automated guided vehicle (AGV) tasks. Various constraints in the scheduling process of the AGV system are analysed, and the types and quantities of AGVs as allocable resources are considered. The multiple‐AGV combined distribution mode and its impact on distribution tasks is also considered. Finally, a multi‐mode resource‐constrained task scheduling model is established for which the object is to minimise material delivery time. Based on the above model, the discrete particle swarm optimization algorithm that improved the basic PSO was proposed. The simulation results with the test set in PSPLIB standard library showed the effectiveness of the improved PSO algorithm

Insights into the transcriptional responses of a microbial community to silver nanoparticles in a freshwater microcosm.

Silver nanoparticles (AgNPs) are widely used because of their excellent antibacterial properties. They are, however, easily discharged into the water environment, causing potential adverse environmental effects. Meta-transcriptomic analyses are helpful to study the transcriptional response of prokaryotic and eukaryotic aquatic microorganisms to AgNPs. In the present study, microcosms were used to investigate the toxicity of AgNPs to a natural aquatic microbial community. It was found that a 7-day exposure to 10 μg L-1 silver nanoparticles (AgNPs) dramatically affected the structure of the microbial community. Aquatic micro eukaryota (including eukaryotic algae, fungi, and zooplankton) and bacteria (i.e., heterotrophic bacteria and cyanobacteria) responded differently to the AgNPs stress. Meta-transcriptomic analyses demonstrated that eukaryota could use multiple cellular strategies to cope with AgNPs stress, such as enhancing nitrogen and sulfur metabolism, over-expressing genes related to translation, amino acids biosynthesis, and promoting bacterial-eukaryotic algae interactions. By contrast, bacteria were negatively affected by AgNPs with less signs of detoxification than in case of eukaryota; various pathways related to energy metabolism, DNA replication and genetic repair were seriously inhibited by AgNPs. As a result, eukaryotic algae (mainly Chlorophyta) dominated over cyanobacteria in the AgNPs treated microcosms over the 7-d exposure. The present study helps to understand the effects of AgNPs on aquatic microorganisms and provides insights into the contrasting AgNPs toxicity in eukaryota and bacteria

Photosynthesis-related gene transcripts in <i>M. aeruginosa</i> under light and dark conditions after H₂O₂ treatment.

<p>The shaded areas correspond to the dark period. Symbols represent mean ± SEM of triplicate cultures. The mRNA amount of all examined genes is normalized to 16S rDNA. The open circle corresponds to the control treatment; the filled circle corresponds to the L0 treatment; the filled square corresponds to the D0 treatment. A: The effect of H₂O₂ on <i>psaB</i> circadian transcript; B: the effect of H₂O₂ on the <i>psbD1</i> circadian transcript; C: the effect of H₂O₂ on the <i>rbcL</i> circadian transcript.</p

Growth of <i>M. aeruginosa</i> that was cultured with H₂O₂ in the first 24 h.

<p>The shaded areas correspond to the dark period. Symbols represent mean ± SEM of triplicate cultures. The open circle corresponds to the control treatment; the filled circle corresponds to the L0 treatment; the filled square corresponds to the D0 treatment.</p

The clock gene transcripts in <i>M. aeruginosa</i> under light and dark conditions after H₂O₂ treatment.

<p>The shaded areas correspond to the dark period. Symbols represent mean ± SEM of triplicate cultures. The mRNA amount of all examined genes is normalized to 16S rDNA. The open circle corresponds to the control treatment; the filled circle corresponds to the L0 treatment; the filled square corresponds to the D0 treatment. A, The effect of H₂O₂ on the <i>kaiA</i> circadian transcript; B, the effect of H₂O₂ on the <i>kaiB</i> circadian transcript; C: the effect of H₂O₂ on the <i>kaiC</i> circadian transcript; D: the effect of H₂O₂ on the <i>sasA</i> circadian transcript.</p

The intracellular microcystin content of <i>M. aeruginosa</i> under light and dark conditions after H₂O₂ treatment.

<p>The shaded areas correspond to the dark period. The symbols represent the mean ± SEM of triplicate cultures. The filled circle corresponds to the L0 treatment; the open circle corresponds to the control treatment; the filled square corresponds to the D0 treatment.</p

The change of microcystin content in water after oxidation by H₂O₂ for various time periods.

<p>The change of microcystin content in water after oxidation by H₂O₂ for various time periods.</p