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381.
New evidence for covalent coupling of peptides to humic acids based on 2D NMR spectroscopy: A means for preservation 总被引:1,自引:0,他引:1
Pang-Hung Hsu 《Geochimica et cosmochimica acta》2005,69(18):4521-4533
Nitrogen immobilization in soils and sediments involving the preservation of peptides is an important yet not well-understood process. Several hypotheses have been proposed for the preservation of peptides in these systems; however, to date, there is no direct molecular-level evidence for any one of several hypotheses. In this study, a synthesized peptide with 15N-labeled amino acid residues was utilized to examine the mechanism by which humic substances from a peat might chemically interact with peptides to induce preservation. Two-dimensional 15N-1H HSQC NMR experiments were performed to evaluate the bonding and nonbonding interactions between 15N-labeled peptide and an Everglades peat humic acid. The observed changes in cross peaks provide the first direct spectroscopic evidence for what we believe to be covalent binding between these substances. Noncovalent interactions between the 15N-labeled peptides and humic acid molecules are also observed in the spectra. Quinone structures in humic acids are suggested to be the important reactive groups, based on reaction of the labeled peptide with a model quinone which shows similar nitrogen-proton correlated peak patterns as is observed in the HSQC NMR spectra of humic acids reacted with the peptide. The Michael reaction with quinone structures is proposed, and this type of reaction provides a mechanism that is consistent with previous observation for the chemistry of sedimentary nitrogen species. 相似文献
382.
Albert S. Chen Ming-Hsi Hsu Wei-Hsien Teng Chen-Jia Huang Sen-Hae Yeh Wan-Yu Lien 《Natural Hazards》2006,37(1-2):107-132
The structural measure was the major solution for flood defense in Taiwan. However, the measure is always limited to the design
standard and cannot prevent the damages when floods exceed certain scale. Therefore, non-structural measures for flood mitigation
are the indispensable complements to structural solutions. The study introduces the establishment of inundation potential
database that provides required information for the non-structural measures in Taiwan. The database was built by numerical
simulations, based on different rainfall scenarios, and has been applied by the local governments of Taiwan for land use managements,
flood warning systems, emergency responses, and flood insurance programs to reduce the flood damages and impacts. 相似文献
383.
Covalent and non-covalent interaction of proteinaceous materials in soils and sediments has been suggested as an important mechanism for immobilizing nitrogen in numerous types of environments. In a previous study (Hsu P.-H., Hatcher, P.G., 2005. New evidence for covalent coupling of peptides to humic acids based on 2D NMR spectroscopy: A means for preservation. Geochimica et Cosmochimica Acta 69, 4521–4533), we provided molecular evidence for covalent, as well as non-covalent, bonding between 15N-labeled peptides and humic acid molecules using the 2D HSQC (heteronuclear single quantum coherence) NMR technique. In this report, we examine the influence of aromaticity and aliphaticity of peptides and humic materials on these covalent and non-covalent interactions. We use 2D NMR techniques to evaluate bonding interactions of 15N labeled peptides, having different aromatic and aliphatic properties, with three humic acids that vary in degree of aromaticity. The peptide containing primarily aromatic amino acid residues is observed to form covalent and non-covalent bonds with mainly aromatic-rich humic acids. The peptide composed of aliphatic amino acid residues shows, on the other hand, only bonding interactions with aliphatic-rich humic acids. These observations provide the first direct molecular evidence that aliphatic functional groups are involved in bonding with proteinaceous materials. The process may play an important role in sequestration of proteinaceous materials in sedimentary systems such as marine systems where the humic materials are mainly aliphatic in nature. 相似文献
384.
Many researches mention the land development in the watershed increases the peak flow rate and volume of the surface runoff. However, another phenomenon, the land development in the lowlands with filling method probably results in flood risk transfer effect, is rarely mentioned. This study took Heshunliao Farm as study object and used SOBEK model to assess the phenomenon. The terrain of this farm was flat and low, at an elevation of about 1.3–3 m before development. A filling method has been adopted to raise the surficial elevation in the development zone to 3–5 m. The western end of the development zone is still maintained its original elevation. The storm sewer system, detention basin, and pumping stations have been built in the development zone. There are two effects in the development of the low-lying land. One is the increase in the peak outflow rate in the development zone. Under a 10-year return period rainfall, the peak outflow rate after development has increased to 9.94 cm, compared to 2.62 cm when there was no development. Another effect is that the disappearance of the original flood-accumulated space due to land development activities transfers the risk of flooding to the surrounding land. Under a 10-year return period rainfall, the flooded area of the developed area was reduced from 78.4 ha before land development to 0.32 ha after the development, while the flooded area of the western end of the development zone increased from 13.28 ha before development to 27.20 ha after development. 相似文献
385.
In August 2009,Typhoon Morakot brought a large amount of rainfall with both high intensity and long duration to a vast area of Taiwan.Unfortunately,this resulted in a catastrophic landslide in Hsiaolin Village,Taiwan.Meanwhile,large amounts of landslides were formed in the Jiaopu Stream watershed near the southeast part of the Hsiaolin Village.The Hsiaolin Village access road(Provincial Highway No.21 and Bridge No.8) was completely destroyed by the landslide and consequent debris flow.The major scope of this study is to apply a debris flow model to simulate the disaster caused by the debris flow that occurred in the Jiaopu Stream during Typhoon Morakot.According to the interviews with local residents,this study applied the destruction time of Bridge No.8 and Chen's house to verify the numerical debris flow model.By the spatial rainfall distributions information,the numerical simulations of the debris flow are conducted in two stages.In the first stage(before the landslide-dam failure),the elevation of the debris flow and the corresponding potential damages toward residential properties were investigated.In the second stage(after the landslidedam failure),comparisons of simulation results between the longitudinal and cross profiles of the Jiaopu Stream were performed using topographic maps and satellite imagery.In summary,applications of the adopted numerical debris flow model have shown positive impact on supporting better understanding of the occurrence and movement of debris flow processes. 相似文献