In‐channel wood is a key component in fluvial ecosystems; however, transport of in‐channel wood during floods can create hazards in urbanized areas. Among the main problems is wood accumulation at bridges, which reduces flow openings, causes blockage and inundation of nearby areas and, eventually, results in structures collapsing. Increasing awareness of the importance of the ecological role of wood in rivers calls for a compromise between the preservation of river ecosystems and management strategies for the prevention of wood‐related hazards. In recent years, knowledge related to in‐channel wood dynamics and hazards has notably increased, and a significant body of valuable information can be found in an extensive number of studies. This review provides a comprehensive summary of the most relevant advances regarding in‐channel wood‐bridge interactions. We review the factors controlling wood accumulation formation and summarize the different approaches used to analyse this process, namely, physical and numerical modelling. Finally, we conclude by highlighting the most important knowledge gaps, addressing particularly underresearched fields and stressing the remaining challenges. 相似文献
Objective: Aim of this work was the synthesis of a methacrylic hyaluronic acid (HA) derivative and the production, via photocrosslinking, of related hydrogels loaded with an endopeptidase intended for a potential oral treatment of celiac disease.
Methods: The methacrylic derivative of HA was prepared through a one-pot procedure involving the reaction with ethylenediamine (EDA) and methacrylic anhydride (MA). The obtained derivative, named HA-EDA-MA, was used to prepare photocrosslinked hydrogels loaded with a prolyl endopeptidase derived from Flavobacterium meningosepticum (PEP FM) able to detoxify gliadin. Obtained hydrogels were recovered as gels or freeze-dried powders.
Results: Hydrogels obtained as freeze-dried powders, are able to protect loaded enzyme from degradation due to freeze-drying process and from alteration during storage, overall in the presence of a cryoprotectant. All photocrosslinked HA-EDA-MA hydrogels (gels and powders) release PEP FM in simulated intestinal fluid in sustained manner and in active form. HA-EDA-MA hydrogels are nontoxic as demonstrated through in vitro studies on BALB 3T3 cells.
Conclusions: Prepared hydrogels show a potential application for oral treatment of celiac disease thanks to the possibility to release enzymes able to detoxify the gliadin peptide that induces the immunogenic response. 相似文献
Lignin, a resistant cell-wall constituent of all vascular plants that consists of ether and carbon-linked methoxyphenols, is still far from being structurally described in detail. The main problem in its structural elucidation is the difficulty of isolating lignin from other wood components without damaging lignin itself. Furthermore, the high number and variegated forms of linkages that occur between the monomeric units and the chemical resistance of certain ether bonds limit the extent to which analytical and degradation procedures can be used to elucidate the lignin structure. Most of our present knowledge about the molecular structure of lignin is based on the analysis of monomers, dimers or, at the most, tetramers of degraded isolated lignins. Mass spectrometry (MS), which offers advantages in terms of speed, specificity, and sensitivity, has revealed to be a very powerful technique in the structural elucidation of lignins, in combination with the great number of chemical and thermal degradation methods available in the study of lignin. Moreover, the recent development of new ionization techniques in MS-electrospray ionization (ESI)-MS and matrix-assisted laser desorption/ionization (MALDI)-MS-has provided new possibilities to also analyze the undegraded lignin macromolecule. 相似文献
The limit of detection of low-molecular weight compounds in tissue sections, analyzed by matrix assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI), was significantly improved by employing sample washing using a pH-controlled buffer solution. The pH of the washing solutions were set at values whereby the target analytes would have low solubility. Washing the tissue sections in the buffered solution resulted in removal of endogenous soluble ionization-suppressing compounds and salts, while the target compound remained in situ with minor or no delocalization during the buffered washing procedure. Two pharmaceutical compounds (cimetidine and imipramine) and one new protease inhibitor compound were successfully used to evaluate the feasibility of the pH-controlled tissue washing protocol for MALDI-MSI. Enhancement in signal-to-noise ratio was achieved by a factor of up to 10. 相似文献
This paper presents a methodology for the estimation of the contribution of direct energy use to the greenhouse gases emissions of cattle, pig and poultry breeding in Cyprus. The energy consumption was estimated using the factors of 2034 MJ/cow, 2182 MJ/sow and 0.002797 MJ/bird. The greenhouse gases emissions for each animal species and energy source were estimated using emission factor of each greenhouse gas according to fuel type as proposed by the IPCC 2006 guidelines and for electricity according to national verified data from the Electricity Authority of Cyprus. Livestock breeding in Cyprus consumes electricity, diesel oil and LPG. The results obtained, show that the emissions from energy use in livestock breeding contribute 16% to the total agricultural energy emissions. Agricultural energy emissions contribute 0.7% to the total energy greenhouse gases (GHG) emissions. The three species of animal considered contribute 3% to their total livestock breeding emissions when compared with enteric fermentation and manure management, of which 2.6% is CO2. These results agree with the findings in available literature. The contribution of direct energy use in the greenhouse gases emissions of livestock breeding could be further examined with the influence of anaerobic digestion to the emissions. 相似文献