This paper presents the experiments and numerical calculations on the laser-induced ignition of single micron-sized aluminum particle in an atmospheric pressure air flow at low Reynolds number. Experimental results demonstrate that the radiation intensity of single micron-sized aluminum particle, during ignition, experiences first sharp rising, stable equilibrium and second steep rising stages. A simplified analytical model was built and numerically solved. Numerical results show that the three distinctive stages represent the heating, melting and evaporation, respectively. Laser radiation mainly contributes to heat aluminum particle, leading to phase transition (melting). The heat released from heterogeneous surface reaction (HSR) domi-nates the temperature rise of the liquid aluminum and accelerate its evaporation. During ignition, the heat loss of natural convection significantly affects the ignition performance of aluminum particle, while the heat loss of radiation toward the surrounding air only affects the evaporation rate. Threshold ignition energy of aluminum particle based on numerical calculations is in good agreement with the experiments, which strongly depends on the particle diameter. Ignition delay time depends on the particle diameter and ignition energy. This study will be beneficial to deeply recognize the ignition mechanism of single micron-sized aluminum particle, especially in the transition region between nanoscale and microscale.

The transport of organic matters to the deep sea constantly occurs in global oceans and in accompany with simultaneous microbial remineralization. However, little is known about the impact of fast sinking organic complex on oceanic deep ecosystem and its interactions with microbes throughout the process of sinking and settling on the sea bottom. In this report, to observe the response of indigenous microorganisms to the newly input of organic matters, we developed a series of deep-sea in situ incubators loaded on the seabed and seamount with various organic substrates of plant and animal origins. Through high-throughput sequencing, we found the bacterial communities, in situ enriched for 4–12 months, were significant different from the control groups. The bacteria of Marinifilaceae were revealed as the key members; in addition, other key decomposers including Spirochaetaceae, Psychromonadaceae, Vibrionaceae, and Moritellaceae were recruited in most assemblages, with varied abundance accordingly and diversified at the operational taxonomic unit (OTU) level. Additionally, sulphate-reducing bacteria (Desulfobulbaceae and Desulfobacteraceae) and sulphur-oxidizing bacteria (Arcobacteraceae and Sulfurovaceae) were the dominant taxa. Interestingly, PICRUSt analysis demonstrated that nitrogen fixation inside the assemblages was enriched in the enrichments with plant detritus or fatty acids. Within the assemblages stimulated by substrates short of nitrogen sources, the microbial network was dominated by cooperative relationships, whereas competition relationships overwhelmed the communities thriving on protein-rich animal tissue. These unique bacterial assemblages driven by newly input organic matters, constitute the microbial carbon pump involved in carbon, sulphur, and nitrogen cycles in oceanic interior.

Background The transport of organic matters to the deep sea constantly occurs in global oceans and in accompany with simultaneous microbial remineralization. However, little is known about the impact of fast sinking organic complex on oceanic deep ecosystem and its interactions with microbes throughout the process of sinking and settling on the sea bottom. In this report, to observe the response of indigenous microorganisms to the newly input of organic matters, we developed a series of deep-sea in-situ incubators loaded on the seabed and seamount with various organic substrates of plant and animal origins. Results The bacterial diversity at the OTU level varied in accordance to organic substrates and geographic locations, but the functional groups are generally similar. The bacteria of Marinifilaceae were revealed as the key member; in addition, other key decomposers including Spirochaetaceae, Psychromonadaceae, Vibrionaceae, Moritellaceae, and Fusobacteriaceae were also recruited in most assemblages with varied abundance accordingly. Interestingly, nitrogen fixation inside the assemblages occurred in the process of polysaccharide decomposing. The microbial co-occurrence analysis revealed that nutrient availability and energy transfer determine relationships cooperation or competition. Within the assemblages stimulated by substrates short of nitrogen sources, the microbial network was dominated by cooperative relationships, whereas competition relationships overwhelmed the communities thriving on proteinous substrates. Conclusions These in-situ observations revealed a unique bacterial assemblage in decomposing diverse newly input organic matters, which may constitute the microbial pumps involved in carbon, sulphur, and nitrogen cycles in oceanic interior.

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Background The transport of organic matters to the deep sea constantly occurs in global oceans and in accompany with simultaneous microbial remineralization. However, little is known about the impact of fast sinking organic complex on oceanic deep ecosystem and its interactions with microbes throughout the process of sinking and settling on the sea bottom. In this report, to observe the response of indigenous microorganisms to the newly input of organic matters, we developed a series of deep-sea in-situ incubators loaded on the seabed and seamount with various organic substrates of plant and animal origins. Results The bacterial diversity at the OTU level varied in accordance to organic substrates and geographic locations, but the functional groups are generally similar. The bacteria of Marinifilaceae were revealed as the key member; in addition, other key decomposers including Spirochaetaceae, Psychromonadaceae, Vibrionaceae, Moritellaceae, and Fusobacteriaceae were also recruited in most assemblages with varied abundance accordingly. Interestingly, nitrogen fixation inside the assemblages occurred in the process of polysaccharide decomposing. The microbial co-occurrence analysis revealed that nutrient availability and energy transfer determine relationships cooperation or competition. Within the assemblages stimulated by substrates short of nitrogen sources, the microbial network was dominated by cooperative relationships, whereas competition relationships overwhelmed the communities thriving on proteinous substrates. Conclusions These in-situ observations revealed a unique bacterial assemblage in decomposing diverse newly input organic matters, which may constitute the microbial pumps involved in carbon, sulphur, and nitrogen cycles in oceanic interior.