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1.
Sci Rep ; 7(1): 7472, 2017 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-28785020

RESUMO

The existing acoustic emission (AE) source location methods assume that acoustic waves propagate along straight lines, and the source location is determined by average wave velocity. Because of the heterogeneity of materials, location results often fail to meet the accuracy requirement. For this reason, an AE source location method considering refraction in different media was proposed in this paper. According to sensor coordinates, the arrival time of acoustic waves, the velocities of acoustic waves in two kinds of media, the space-time relation equations of the AE source point and the measuring point were established by the precise coordinates of the AE source based on Snell's law. The feasibility of the algorithm was verified by experiments, and the factors influencing location accuracy were also analysed. The results show that the algorithm proposed in this paper is applicable for both the same medium and different media, and the accuracy of localization is not affected by the ratio of wave velocities in two media or the distance from the AE source to the refraction surface.

2.
Appl Microbiol Biotechnol ; 93(5): 2193-203, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-21847510

RESUMO

Knowledge about methanotrophs and their activities is important to understand the microbial mediation of the greenhouse gas CH(4) under climate change and human activities in terrestrial ecosystems. The effects of simulated warming and sheep grazing on methanotrophic abundance, community composition, and activity were studied in an alpine meadow soil on the Tibetan Plateau. There was high abundance of methanotrophs (1.2-3.4 × 10(8) pmoA gene copies per gram of dry weight soil) assessed by real-time PCR, and warming significantly increased the abundance regardless of grazing. A total of 64 methanotrophic operational taxonomic units (OTUs) were obtained from 1,439 clone sequences, of these OTUs; 63 OTUs (98.4%) belonged to type I methanotrophs, and only one OTU was Methylocystis of type II methanotrophs. The methanotroph community composition and diversity were not apparently affected by the treatments. Warming and grazing significantly enhanced the potential CH(4) oxidation activity. There were significantly negative correlations between methanotrophic abundance and soil moisture and between methanotrophic abundance and NH(4)-N content. The study suggests that type I methanotrophs, as the dominance, may play a key role in CH(4) oxidation, and the alpine meadow has great potential to consume more CH(4) under future warmer and grazing conditions on the Tibetan Plateau.


Assuntos
Bactérias/classificação , Bactérias/metabolismo , Biota , Metano/metabolismo , Microbiologia do Solo , Amônia/análise , Animais , DNA Bacteriano/química , DNA Bacteriano/genética , Dados de Sequência Molecular , Oxirredução , Reação em Cadeia da Polimerase em Tempo Real , Análise de Sequência de DNA , Ovinos , Solo/química , Temperatura , Tibet
3.
Ying Yong Sheng Tai Xue Bao ; 22(10): 2567-73, 2011 Oct.
Artigo em Chinês | MEDLINE | ID: mdl-22263459

RESUMO

Taking the typical forest types Pinus elliottii var. elliotttii, Araucaria cunninghamii, and Agathis australis in southern Queensland of Australia as test objects, an investigation was made on the soil soluble organic carbon (SOC) and nitrogen (SON), microbial biomass C (MBC) and N (MBN), and enzyme activities, aimed to understand the effects of forest type on soil quality. In the three forests, soil SOC content was 552-1154 mg kg(-1), soil SON content was 20.11-57.32 mg kg(-1), soil MBC was 42-149 mg kg(-1), soil MBN was 7-35 mg kg(-1), soil chitinase (CAS) activity was 2.96-7.63 microg g(-1) h(-1), soil leucine aminopeptidase (LAP) activity was 0.18-0.46 microg g(-1) d(-1), soil acid phosphatase (ACP) activity was 16.5-29.6 microg g(-1) h(-1), soil alkaline phosphatase (AKP) activity was 0.79-3.42 microg g(-1) h(-1), and soil beta-glucosidase (BG) activity was 3.71-9.93 microg g(-1) h(-1). There was a significant correlation between soil MBC and MBN. Soil SOC content and soil CAS and LAP activities decreased in the order of P. elliottii > A. cunninghamii > A. australis, soil SON content decreased in the order of A. cunninghamii > A. australis > P. elliottii and was significantly higher in A. cunninghamii than in P. elliottii forest (P < 0.05), soil MBC and MBN and AKP activity decreased in the order of A. australis > P. elliottii > A. cunninghamii, and soil ACP and BG activities decreased in the order of P. elliottii > A. australis > A. cunninghamii. Among the test soil biochemical factors, soil MBC, MBN, SON, and LAP had greater effects on the soil quality under the test forest types.


Assuntos
Enzimas/metabolismo , Compostos Orgânicos/análise , Microbiologia do Solo , Solo/análise , Árvores/classificação , Fosfatase Ácida/metabolismo , Biomassa , Quitinases/metabolismo , Cunninghamia/crescimento & desenvolvimento , Leucil Aminopeptidase/metabolismo , Pinus/crescimento & desenvolvimento , Árvores/crescimento & desenvolvimento
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