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- Jones, D L, et al.
(author)
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Organic acid behavior in soils - misconceptions and knowledge gaps
- 2003
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In: Plant and Soil. - 0032-079X .- 1573-5036. ; 248:1-2, s. 31-41
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Journal article (peer-reviewed)abstract
- Organic acids have been hypothesized to perform many functions in soil including root nutrient acquisition, mineral weathering, microbial chemotaxis and metal detoxification. However, their role in most of these processes remains unproven due to a lack of fundamental understanding about the reactions of organic acids in soil. This review highlights some of the knowledge gaps and misconceptions associated with the behavior of organic acids in soil with particular reference to low-molecular-weight organic acids (e.g., citrate, oxalate, malate) and plant nutrient acquisition. One major concern is that current methods for quantifying organic acids in soil may vastly underestimate soil solution concentrations and do not reveal the large spatial heterogeneity that may exist in their concentration (e.g., around roots or microbes). Another concern relates to the interaction of organic acids with the soil's solid phase and the lack of understanding about the relative importance of processes such as adsorption versus precipitation, and sorption versus desorption. Another major knowledge gap concerns the utilization of organic acids by the soil microbial community and the forms of organic acids that they are capable of degrading (e.g., metal-complexed organic acids, adsorbed organic acids etc). Without this knowledge it will be impossible to obtain accurate mathematical models of organic acid dynamics in soil and to understand their role and importance in ecosystem processes. Fundamental research on organic acids and their interaction with soil still needs to be done to fully elucidate their role in soil processes.
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| 4. |
- Gozar, A, et al.
(author)
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Inhomogeneous CuO6 tilt distribution and charge-spin correlations in La2-x-yNdySrxCuO4 around the commensurate hole concentration
- 2003
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 68:5, s. 1-052511
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Journal article (peer-reviewed)abstract
- Phononic and magnetic Raman scattering are studied in La2-x-yNdySrxCuO4 with three doping concentrations: x1/8, y = 0; x1/8, y = 0.4; and x = 0.01, y = 0. We observe strong disorder in the tilt pattern of the CuO6 octahedra in both the orthorhombic and tetragonal phases that persist down to 10 K and are coupled to bond disorder in the cation layers around 1/8 doping independent of Nd concentration. The weak magnitude of existing charge-spin modulations in the Nd-doped structure does not allow us to detect the specific Raman signatures of lattice dynamics or two-magnon scattering around 2200 cm–1. ©2003 The American Physical Society
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| 6. |
- Palmqvist, Anders, 1966, et al.
(author)
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LOTUS: A co-operation for low temperature urea-based selective catalytic reduction of NOx
- 2004
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In: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627. ; 20014
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Journal article (peer-reviewed)abstract
- The European research co-operation Lotus is presented. The main objectives of the project were i) to show the potential for a urea-based SCR system to comply with the EU standard of years 2005 and 2008 for heavy-duty Diesel engines for different driving conditions with optimal fuel consumption, ii) to reach 95 % conversion of NOx at steady state at full load on a Euro III. engine, iii) to reach 75 % NOx reduction for exhaust temperatures between 200-300°C, and 85 % average NOx reduction between 200-500°C. The energy content of the consumed urea should not exceed 1.0 %, calculated as specific fuel consumption. These targets were met in May 2003 and the Lotus SCR system fulfilled the Euro V NOx legislative objectives for year 2008. Copyright © 2004 SAE International.
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| 8. |
- Tjabringa, G Sandra, et al.
(author)
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The antimicrobial peptide LL-37 activates innate immunity at the airway epithelial surface by transactivation of the epidermal growth factor receptor
- 2003
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In: Journal of Immunology. - 1550-6606. ; 171:12, s. 6690-6696
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Journal article (peer-reviewed)abstract
- Antimicrobial peptides produced by epithelial cells and neutrophils represent essential elements of innate immunity, and include the defensin and cathelicidin family of antimicrobial polypeptides. The human cathelicidin cationic antimicrobial protein-18 is an antimicrobial peptide precursor predominantly expressed in neutrophils, and its active peptide LL-37 is released from the precursor through the action of neutrophil serine proteinases. LL-37 has been shown to display antimicrobial activity against a broad spectrum of microorganisms, to neutralize LPS bioactivity, and to chemoattract neutrophils, monocytes, mast cells, and T cells. In this study we show that LL-37 activates airway epithelial cells as demonstrated by activation of the mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) and increased release of IL-8. Epithelial cell activation was inhibited by the MAPK/ERK kinase (MEK) inhibitors PD98059 and U0126, by the epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor AG1478, by blocking anti-EGFR and anti-EGFR-ligand Abs, and by the metalloproteinase inhibitor GM6001. These data suggest that LL-37 transactivates the EGFR via metalloproteinase-mediated cleavage of membrane-anchored EGFR-ligands. LL-37 may thus constitute one of the mediators by which neutrophils regulate epithelial cell activity in the lung.
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