Ecology. Resilience to blooms     

Brookes JD  Carey CC 《Science (New York, N.Y.)》2011,334(6052):46-47

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Diameter-Selective Raman Scattering from Vibrational Modes in Carbon Nanotubes   总被引：1，自引：0，他引：1  

AM Rao  E Richter  S Bandow  B Chase  PC Eklund  KA Williams  S Fang  KR Subbaswamy  M Menon  A Thess  RE Smalley  G Dresselhaus  MS Dresselhaus 《Science (New York, N.Y.)》1997,275(5297):187-191

Single wall carbon nanotubes (SWNTs) that are found as close-packed arrays in crystalline ropes have been studied by using Raman scattering techniques with laser excitation wavelengths in the range from 514.5 to 1320 nanometers. Numerous Raman peaks were observed and identified with vibrational modes of armchair symmetry (n, n) SWNTs. The Raman spectra are in good agreement with lattice dynamics calculations based on C-C force constants used to fit the two-dimensional, experimental phonon dispersion of a single graphene sheet. Calculated intensities from a nonresonant, bond polarizability model optimized for sp2 carbon are also in qualitative agreement with the Raman data, although a resonant Raman scattering process is also taking place. This resonance results from the one-dimensional quantum confinement of the electrons in the nanotube.  相似文献   

Biodiesel Co-Product (BCP) amendment drives beneficial soil microbiome assembly promoting acid soil health     

Qunli Shen  Paul Voroney  Philip C. Brookes  Ahmed S. Elrys  Mengjie Yu  Wei-Qin Su  Lei Meng  Meng Li 《European Journal of Soil Science》2023,74(4):e13402

Biodiesel Co-Product (BCP) amendment has been shown to decrease both nitrate leaching and nitrous oxide (N₂O) emissions in acidic soil; however, the effects of BCP on the soil microbiome have not been investigated thoroughly. In this study, we investigated the response of prokaryotic and fungal communities in aspects of structure, diversity, and co-occurrence network to the BCP amendment following complete mixing application (0–18-cm depth) of 1.5 mg BCP-C g⁻¹ and surface application (0–6-cm depth) of 4.5 mg BCP-C g⁻¹ via high-throughput 16S rRNA and internal transcribed spacer (ITS) amplicon sequencing. The amendment altered microbial communities significantly by increasing the relative abundances of Proteobacteria (Burkholderia) and Ascomycota (Trichoderma) in prokaryotic and fungal communities, respectively. Only a higher rate application (4.5 mg BCP-C g⁻¹) decreased prokaryotic alpha diversity, whereas all rates of amendment decreased fungal diversity. The co-occurrence network of prokaryotes had more nodes and links and a higher average degree and clustering coefficient than the fungal network with BCP addition. The majority of keystone species in prokaryotic and fungal networks were from Proteobacteria and Ascomycota taxa. Of note, the BCP amendment significantly increased the OTU numbers of potential biocontrol agents, including Trichoderma (T.) spirale, T. koningiopsis, and T. virens, etc., while decreased OTU numbers related to plant pathogens species, particularly in the complete mixing application. Our work highlights the potential for BCP amendments to promote the assembly of a healthy soil microbiome by enhancing the abundance of potential biocontrol microbes while reducing plant pathogens species, which may contribute to soil health.  相似文献   

Effects of Cd,Zn, or both on soil microbial biomass and activity in a clay loam soil     

Giancarlo Renella  Amar M. Chaudri  Céline M. Falloon  Loretta Landi  Paolo Nannipieri  Philip C. Brookes 《Biology and Fertility of Soils》2007,43(6):751-758

We investigated Cd, Zn, and Cd + Zn toxicity to soil microbial biomass and activity, and indigenous Rhizobium leguminosarum biovar trifolii, in two near neutral pH clay loam soils, under long-term arable and grassland management, in a 6-month laboratory incubation, with a view to determining the causative metal. Both soils were amended with Cd- or Zn-enriched sewage sludge, to produce soils with total Cd concentrations at four times (12 mg Cd g⁻¹ soil), and total Zn concentrations (300 mg Zn kg⁻¹ soil) at the EU upper permitted limit. The additive effects of Cd plus Zn at these soil concentrations were also investigated. There were no significant differences in microbial biomass C (B _C), biomass ninhydrin N (B _N), ATP, or microbial respiration between the different treatments. Microbial metabolic quotient (defined as qCO₂ = units of CO₂–C evolved unit⁻¹ biomass C unit⁻¹ time) also did not differ significantly between treatments. However, the microbial maintenance energy (in this study defined as qCO₂-to-μ ratio value, where μ is the growth rate) indicated that more energy was required for microbial synthesis in metal-rich sludge-treated soils (especially Zn) than in control sludge-treated soils. Indigenous R. leguminosarum bv. trifolii numbers were not significantly different between untreated and sludge-treated grassland soils after 24 weeks regardless of metal or metal concentrations. However, rhizobial numbers in the arable soils treated with metal-contaminated sludges decreased significantly (P < 0.05) compared to the untreated control and uncontaminated sludge-treated soils after 24 weeks. The order of decreasing toxicity to rhizobia in the arable soils was Zn > Cd > Cd + Zn.  相似文献