Synthesis and influencing factors of high-performance concrete based on copper tailings for efficient solidification of heavy metals.

Copper tailings containing a large amount of heavy metals such as Pb, Cu, As, Mn, and Cr discharged from its mining are a typical bulk solid waste, which is highly hazardous to human and the environment. This research proposed a sustainable and effective method for the environmentally sound utilization of copper tailings solid waste. A high-strength concrete material with copper tailings as the main raw material was successfully prepared, with a 28-day compressive strength of up to 85.35 MPa, the flexural strength reached 12.46 MPa, and the tailings utilization rate of 60%. The mechanical properties and heavy metal stabilization properties of the prepared high-performance concrete were obtained by adding coarse aggregates such as river sand, while changing the sand rate, cementitious material admixture and water-cement ratio. A long-term leaching experiment of the high-strength concrete material with 190 day was carried and proved that the material can be made with low or no risk of heavy metal contamination in copper tailings. Incorporation of copper tailings into the high-performance concrete hydration mainly contains three mechanisms: (i) Pore sealing effect generated by the formation of tailings geopolymer prompted the hardening of the geopolymer layer to form a monolithic package structure; (ii) The active SiO2 material in copper tailings reacts with Ca(OH)2 in the hydration products to produce a strong volcanic ash effect; (iii) the primary hydration of 3CaO·SiO2(C3S) and 3CaO·Al2O3(C3A) in the cement, and the secondary hydration reaction induced by the copper tailings and silica fume. These mechanisms are blended with each other to form a dense microstructure of the slurry, which embodies extremely high mechanical properties on a macroscopic scale, providing a reference role for the bulk utilization of copper tailings.

Quantification and pharmacokinetics of alpinetin in rat plasma by UHPLC-MS/MS using protein precipitation coupled with dilution approach to eliminate matrix effects.

Alpinetin, a bioactive flavonoid, has attracted great attention due to its diverse therapeutic effects, namely anti-oxidant, anti-tumor and anti-inflammatory effects with low systemic toxicity. Various determination methods have been developed in quality control and plant chemistry areas. However, quantification and pharmacokinetics of alpinetin in biological matrix have not been studied. In the present research, a sensitive, efficient and reliable ultrahigh performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the determination of alpinetin in rat plasma was developed and validated. Plasma samples were processed with protein precipitation (PP) followed by a 5-fold acetonitrile/water (50:50, v/v) dilution to significantly decrease matrix effect which exited in one step PP method. Determination of alpinetin was conducted using positive electrospray ionization tandem mass spectrometry in multiple reaction monitoring mode. Results demonstrated that the method was precise (3.3%-12.3%), accurate (-5.8% to 10.8%) and linear in the range of 1-1000 ng/mL. The new developed method was subsequently applied to a pharmacokinetic research of alpinetin following oral and intravenous dosing to healthy Sprague-Dawley rats. Alpinetin was demonstrated rapid absorption after oral administration with an absolute bioavailability of ∼15.1% and extensive distribution after dosing.