Numerical Modeling of CO2 and Brine Leakage through Open Fracture in a Fault Zone: Open Channel Flow or Darcy Flow

Understanding fluids migration and leakage risk along the fault zone is necessary to guarantee the safety of CO2 geological storage. The validity of Darcy’s law gets challenged in dealing with the flow in open fractures since the occurring of turbulence flow. In this study, we develop a 2D model with usage of T2Well, an integrated wellbore-reservoir simulator, to investigate the leakage problem along open fractures which are embedded in a fault zone from the deep injection reservoir to shallow aquifers. The results record a positive feedback of gas expansion and pressure response in fracture, which causes a quick downward propagation of highly gas saturated zone from the top of fracture and an easy gas breakthrough in the shallower aquifers. The decreasing of aperture size of fracture significantly enhances the leakage rates in fracture, but with less influences as aperture increases. In comparison, the Equivalent Porous Media models show a good approximation with the momentum model of large apertures but poor for the small one. Nevertheless, the differences are small in terms of final CO2 distribution among various aquifers, suggesting that Darcy’s law may be still “effective” in solving flow problem along fractures in a constant injection system at a large time scale

A novel tin-bismuth alloy electrode for anodic stripping voltammetric determination of zinc

We report on a novel tin-bismuth alloy electrode (SnBiE) for the determination of trace concentrations of zinc ions by square-wave anodic stripping voltammetry without deoxygenation. The SnBiE has the advantages of easy fabrication and low cost, and does not require a pre-treatment (in terms of modification) prior to measurements. A study on the potential window of the electrode revealed a high hydrogen overvoltage though a limited anodic range due to the oxidation of tin. The effects of pH value, accumulation potential, and accumulation time were optimized with respect to the determination of trace zinc(II) at pH 5.0. The response of the SnBiE to zinc(II) ion is linear in the 0.5-25 mu M concentration range. The detection limit is 50 nM (after 60 s of accumulation). The SnBiE was applied to the determination of zinc(II) in wines and honeys, and the results were consistent with those of AAS.We report on a novel tin-bismuth alloy electrode (SnBiE) for the determination of trace concentrations of zinc ions by square-wave anodic stripping voltammetry without deoxygenation. The SnBiE has the advantages of easy fabrication and low cost, and does not require a pre-treatment (in terms of modification) prior to measurements. A study on the potential window of the electrode revealed a high hydrogen overvoltage though a limited anodic range due to the oxidation of tin. The effects of pH value, accumulation potential, and accumulation time were optimized with respect to the determination of trace zinc(II) at pH 5.0. The response of the SnBiE to zinc(II) ion is linear in the 0.5-25 mu M concentration range. The detection limit is 50 nM (after 60 s of accumulation). The SnBiE was applied to the determination of zinc(II) in wines and honeys, and the results were consistent with those of AAS

Voltammetric determination of nitrate in water samples at copper modified bismuth bulk electrode

Voltammetric determination of nitrate () in 0.1M Na2SO4 solution (pH 2.0) at copper modified bismuth bulk (BiB/Cu) electrode was presented in this article. Owing to the unique properties of bismuth bulk electrode, the proposed BiB/Cu electrode can be used for determination of without any deoxygenating pretreatment and shows low detection limit (6 mu M), wide linear range (13 mu M to 3mM), high sensitivity (31.8 mu AmM(-1)cm(-2)) and good anti-interference. The practical application of the proposed BiB/Cu electrode has been carried out for determination of in real environmental water samples

Engineered Extracellular Vesicles for Cancer Therapy

Extracellular vesicles (EVs) have emerged as a novel cell-free strategy for the treatment of many diseases including cancer. As a result of their natural properties to mediate cell-to-cell communication and their high physiochemical stability and biocompatibility, EVs are considered as excellent delivery vehicles for a variety of therapeutic agents such as nucleic acids and proteins, drugs, and nanomaterials. Increasing studies have shown that EVs can be modified, engineered, or designed to improve their efficiency, specificity, and safety for cancer therapy. Herein, a comprehensive overview of the recent advances in the strategies and methodologies of engineering EVs for scalable production and improved cargo-loading and tumor-targeting is provided. Additionally, the potential applications of engineered EVs in cancer therapy are discussed by presenting prominent examples, and the opportunities and challenges for translating engineered EVs into clinical practice are evaluated.Peer reviewe

On-Line Determination of Lead in Tap Waters at Two-Step Prepared Bismuth Electrode

An anodic stripping analysis system based on two-step prepared bismuth electrode for on-line determination of lead (Pb2+) in tap water samples is presented here. Such two-step prepared electrode modified in-situ and ex-situ bismuth film shows remarkably improved sensitivity to Pb2+ in acidic solution (pH &lt;= 2). The designed electrode has been successfully used for determination of Pb2+ in acidic solution by anodic stripping voltammetry with a linear range of 1.3-20 mu gL(-1). The sensitivity and detection limit are 19 nAL mu g(-1) and 0.8 mu gL(-1), respectively. The practical application of the proposed electrode has been carried out for the on-line determination of trace levels of Pb2+ in real tap water samples.An anodic stripping analysis system based on two-step prepared bismuth electrode for on-line determination of lead (Pb(2+)) in tap water samples is presented here. Such two-step prepared electrode modified in-situ and ex-situ bismuth film shows remarkably improved sensitivity to Pb(2+) in acidic solution (pH <= 2). The designed electrode has been successfully used for determination of Pb(2+) in acidic solution by anodic stripping voltammetry with a linear range of 1.3-20 mu gL(-1). The sensitivity and detection limit are 19 nAL mu g(-1) and 0.8 mu gL(-1), respectively. The practical application of the proposed electrode has been carried out for the on-line determination of trace levels of Pb(2+) in real tap water samples

Determination of Trace Copper in Water Samples by Anodic Stripping Voltammetry at Gold Microelectrode

The applicability of gold microelectrode of 25 mu m diameter for electrochemical determination of trace copper ions (Cu(2+)) in water samples by anodic stripping voltammetry (ASV) has been demonstrated. The analysis of Cu(2+) at gold microelectrode includes two steps. Cu(2+) ions are firstly reduced and accumulated on the microelectrode surface during an accumulation step, then oxidized during the positive potential sweep. Due to the rapid mass transporting and low background current of gold microelectrode, low detection limit (0.3 nM) and wide linear range (1.0-90 nM) can be obtained. The practical application of gold microelectrode was verified by determination of trace level of Cu(2+) in tap water, lake water and commercial drinking water samples

New application of tin-bismuth alloy for electrochemical determination of cadmium

Electrochemical properties of commercial tin-bismuth alloy were investigated and the tin-bismuth alloy based electrode was used for stripping voltammetric determination of cadmium (Cd2+) for the first time. Electrodeposition and electrochemical stripping of Cd2+ on tin-bismuth alloy electrode (SnBiE) were implemented and the results with an excellent linear dynamic range of 5-500 nM, a correlation coefficient of 0.999 and a detection limit of 1.1 nm were obtained under the optimal experimental conditions. It revealed that not only does this environment friendly alloy electrode material have a high hydrogen overvoltage and relatively wide potential window, but also has excellent repeatability and reproducibility. The practical application was carried out for the determination of Cd2+ in food samples and the results were consistent well with those by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS).Electrochemical properties of commercial tin-bismuth alloy were investigated and the tin-bismuth alloy based electrode was used for stripping voltammetric determination of cadmium (Cd2+) for the first time. Electrodeposition and electrochemical stripping of Cd2+ on tin-bismuth alloy electrode (SnBiE) were implemented and the results with an excellent linear dynamic range of 5-500 nM, a correlation coefficient of 0.999 and a detection limit of 1.1 nm were obtained under the optimal experimental conditions. It revealed that not only does this environment friendly alloy electrode material have a high hydrogen overvoltage and relatively wide potential window, but also has excellent repeatability and reproducibility. The practical application was carried out for the determination of Cd2+ in food samples and the results were consistent well with those by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). (C) 2011 Elsevier B.V. All rights reserved