Development of an isotopic stream index connecting physiographic characteristics of montane catchments.

This study is to develop an isotopic catchment-effect index (CEI) connecting the physiographic characteristics of stream catchments. A CEI, describing the extent of difference in stable water isotopic compositions (δ values) between stream water and local precipitation at any given sampling site, can help in judging whether water resource management should be focused on upstream regions of streams or local hydrology issues. To establish the isotopic CEI, this study measured δ values of stream water and derived δ18 O of local precipitation based on regional isotopic altitude gradient at montane catchments of various sizes. Results indicate that the CEI is strongly related to catchment physiographic characteristics, such as length of main stream, mean area, mean elevation, perimeter, and slope. These characteristics are considered important indices of streamflow. Based on mathematical regression modeling describing the relationships between CEI and respective physiographic factors, CEI values can predict respective physiographic factors and vice versa. Moreover, according to the multiple equations derived in this study, catchments of larger size and steeper slope give elevated CEI values while greater stream length reduces the CEI's value. A greater CEI value indicates that local stream water is principally sourced from upstream reaches rather than contributions from local precipitation. In addition, CEI values are greater in winter than in summer resulting from monsoon effect. Consequently, this study establishes CEI as a useful descriptor of the physiographic characteristics of catchments.

Substrate-independent, Schiff base interactions to fabricate lysine-functionalized surfaces with fibrinolytic activity.

Mimicking natural fibrinolytic mechanisms that covalently bind lysine-ligands (free ε-amino and carboxylic groups) onto biomaterial surfaces is an attractive strategy to prevent clot formation on blood contact materials. However, the modification process is typically complicated and limited due to the diversity of biomaterials. Herein, we describe a simple, substrate-independent protocol to prepare a lysine-ligand functionalized layer on biomaterial surfaces. This approach is based on the adsorption and cross-linking of aldehyde-functionalized poly(N-(2,2-dimethoxyethyl)methacrylamide) (APDMEA) and amino-functionalized polymethacryloyl-l-lysine (APMLys) on a variety of substrates, such as polyurethane (PU), polydimethylsiloxane (PDMS), polyvinylchloride (PVC), stainless steel (SS) and cellulose acetate (CA). The lysine-ligand functionalized layer on substrates highly enhanced the specific adsorption of plasminogen from plasma and showed good chemical stability and excellent biocompatibility with L929 cells using the MTT assay. Moreover, for example, after the adsorbed plasminogen was activated and converted into plasmin, the fibrinolytic functionalization of CA was demonstrated using a modified plasma recalcification assay. Collectively, considering the advantages of simplicity, environmental friendliness and substrate-independence, the present study might therefore represent a general approach for the construction of a biointerface with fibrinolytic activity.

Assessing the authenticity of commercial deep-sea drinking water by chemical and isotopic approaches.

This study combines stable isotopes and chemical elements with statistical principal component analysis (PCA) to assess the authenticity of bottled commercial drinking water desalinized from deep seawater in the Taiwan market. Isotopic results indicate that true bottled deep-sea drinking water (DSDW) exhibits about 0 ‰ for both δ(2)H and δ(18)O values, which are values similar to those of open seawater. By comparison, suspected counterfeit DSDW products display δ(2)H and δ(18)O values of around -51 ‰ and -8 ‰, respectively. These values are representative of terrestrial freshwater. In addition, suspected counterfeit DSDWs have δ and electrical conductivity values similar to a mixed water (MW) product that was manufactured by purifying terrestrial freshwater and adulterating this with small amounts of brine. Furthermore, PCA results indicate the chemical constitution of suspected DSDW products to be similar to the MW product which falls between purified terrestrial freshwater and desalinized open seawater. These similarities imply that suspected counterfeit DSDW products are manufactured in a similar manner to the declared MW product. This study demonstrates how combining knowledge of stable water isotopes and PCA can be used in assessing the authenticity of commercial DSDW products. The method should be of great interest to similar investigations elsewhere.