Examining a Coupled Continuum Pipe-Flow Model for Groundwater Flow and Solute Transport in a Karst aquifer

A coupled continuum pipe-flow (CCPF) model has been de­veloped for groundwater flow and solute transport in a karst aquifer withconduits. Groundwater flow in conduits is simu­lated througha pipe flow model and flow in fissured matrix rock is described by Darcy’s law. Water mass exchange between the two domains is modeled by a first-order exchange rate method. In this study, we investigate mathematical well-posed­ness (mathematical term, whichmeans solution existence and uniqueness) of the CCPF model, develop a finite elementary method to numerically approximate the mathematical model and study the convergence of the numerical method. The study results prove the modeling approachis mathematically well posed and numerically converged. To study the accuracy of the CCPF model, a recently developed Stokes-Darcy (SD) model and CCPF model are compared withlaboratory experimental results. It was found that the SD model simulations matchwell withexperimental results, but the CCPF model overestimates the hydraulic head in the matrix, especially around the matrix and conduit interface. The model underestimates solute trans­port in the conduit and does not capture the plume distribution in the matrix. In comparison withthe SD model, the CCPF model requires an additional parameter, the first-order mass exchange rate, and the parameter is normally obtained throughinverse method curve fitting. The SD method may provide an approachto directly estimate the parameter value

Numerical Simulation of Groundwater Flow and Solute Transport in a Karst Aquifer with Conduits

Numerical simulation of groundwater flow and solute transport in a dual-permeability karst aquifer is a challenging issue, since groundwater flow in karst conduit network can become non-darcian even turbulent flow. The discrete-continuum model is a relatively new modeling method, which accounts for turbulent and laminar flow in karst aquifer. MODFLOW-CFP (Conduit Flow Process) is compared to the MODFLOW, a numerical code based on Darcy law, to evaluate the accuracy in a sub-regional scale karst aquifer. MODFLOW-CFP is more accurate than the MODFLOW when comparing the head simulation results with field measurements. After that, the CFPv2 and UMT3D numerical models are applied in the WKP to establish a sub-regional scale model to simulate chloride transport processes in the last four decades, and to predict contamination development. Numerical simulation results indicate sprayfields are the major chloride source in the study region. Conduit networks significantly control solute transport and contaminant distribution in the study region. Chloride transports through conduits rapidly and spread to several large contamination plumes in a short period. Chloride concentration started to increase in 1980s due to the operation of sparyfield. Solute transport simulation results by discrete-continuum models are more accurate because of the precise description of conduit network

Influence of lunar semidiurnal tides on groundwater dynamics in estuarine aquifers

The influence of lunar semidiurnal tides on coastal groundwater aquifers has been conceptualized for decades. However, a thorough understanding of the impact of tides on groundwater dynamics due to the widely distributed waterways and heterogeneous sediments in estuarine aquifers, is still needed. This study shows the tidal impact on groundwater dynamics in the Pearl River estuary in southeast China through wavelet and time series analysis. The groundwater level and electrical conductivity (EC), as well as tidal levels, were monitored in several observation wells and tidal stations to determine how the estuarine groundwater levels respond to tidal forcing. The results show that the groundwater fluctuations have short periodicities of 0.51 and 1 day corresponding to major tidal constituents of M2 (semidiurnal) and K1 and O1 (diurnal) signals, respectively. The significant impacts decrease with increasing distance inland of the locations of the wells. Additionally, the coherence analysis displays a higher correlation between tides and groundwater levels for the spring tide than for the neap tide. The tidal influences on groundwater EC are weak compared to those on groundwater levels. In addition, when the tidal level increases, the EC decreases in wells located in the estuarine entrance. This is related to the high salinity of retained paleo-seawater in the strata lenses. A conceptual model is proposed to illustrate the complex groundwater flow dynamics. The model may provide useful insights into the understanding of similar systems located in geographically different coastal regions.© 2020 Springer. This is a post-peer-review, pre-copyedit version of an article published in Hydrogeology Journal. The final authenticated version is available online at: http://dx.doi.org/10.1007/s10040-020-02136-8fi=vertaisarvioitu|en=peerReviewed

Curcumin activates the p38MPAK-HSP25 pathway in vitro but fails to attenuate diabetic nephropathy in DBA2J mice despite urinary clearance documented by HPLC

<p>Abstract</p> <p>Background</p> <p>Curcumin has anti-inflammatory, anti-oxidant, and anti-proliferative properties, and depending upon the experimental circumstances, may be pro- or anti-apoptotic. Many of these biological actions could ameliorate diabetic nephropathy.</p> <p>Methods/Design</p> <p>Mouse podocytes, cultured in basal or high glucose conditions, underwent acute exposure to curcumin. Western blots for p38-MAPK, COX-2 and cleaved caspase-3; isoelectric focusing for HSP25 phosphorylation; and DNase I assays for F- to G- actin cleavage were performed for <it>in vitro </it>analyses. <it>In vivo </it>studies examined the effects of dietary curcumin on the development of diabetic nephropathy in streptozotocin (Stz)-induced diabetes in DBA2J mice. Urinary albumin to creatinine ratios were obtained, high performance liquid chromatography was performed for urinary curcuminoid measurements, and Western blots for p38-MAPK and total HSP25 were performed.</p> <p>Results</p> <p>Curcumin enhanced the phosphorylation of both p38MAPK and downstream HSP25; inhibited COX-2; induced a trend towards attenuation of F- to G-actin cleavage; and dramatically inhibited the activation of caspase-3 in <it>vitro</it>. In curcumin-treated DBA2J mice with Stz-diabetes, HPLC measurements confirmed the presence of urinary curcuminoid. Nevertheless, dietary provision of curcumin either before or after the induction of diabetes failed to attenuate albuminuria.</p> <p>Conclusions</p> <p>Apart from species, strain, early differences in glycemic control, and/or dosing effects, the failure to modulate albuminuria may have been due to a decrement in renal HSP25 or stimulation of the 12/15 lipoxygenase pathway in DBA2J mice fed curcumin. In addition, these studies suggest that timed urine collections may be useful for monitoring curcumin dosing and renal pharmacodynamic effects.</p

The Concise Guide to PHARMACOLOGY 2023/24: Ion channels.

The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and over 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (https://www.guidetopharmacology.org/), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.16178. Ion channels are one of the six major pharmacological targets into which the Guide is divided, with the others being: G protein-coupled receptors, nuclear hormone receptors, catalytic receptors, enzymes and transporters. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate