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In the field of soil stabilization, only calcium silicate hydrate (CSH) and ettringite (AFt) as hydration products have been reported to directly contribute to the strength enhancement of the soil. A chloride dredger fill, an artificial chloride saline soil, and a non-saline soil were stabilized by Portland cement (PC) and PC with Ca(OH)2 (CH) with different contents. A series of unconfined compressive strength (UCS) tests of stabilized soil specimen after curing for 7 d and 28 d were carried out, and the hydration products and microstructure of the specimens were observed by X-ray diffractometry (XRD), scanning electronic microscopy (SEM), and energy-dispersive X-ray analysis (EDXA). The results showed that the strengths of PC+CH-stabilized chloride saline soils were much higher than those of PC-stabilized soils. A new hydration product of calcium aluminate chloride hydrate, also known as Friedel’s salt, appeared in the PC+CH-stabilized chloride saline soils. The solid-phase volume of Friedel’s salt expanded during the formation of the hydrate; this volume filled the pores in the stabilized soil. This pore-filling effect was the most important contribution to the significantly enhanced strength of the PC+CH-stabilized chloride saline soils. On the basis of this understanding, a new optimized stabilizer was designed according to the concept that the chloride in saline soil could be utilized as a component of the stabilizer. The strength of the chloride saline soils stabilized by the optimized stabilizer was even further increased compared with that of the PC+CH-stabilized soils.

Based on three different kinds of conductive paths in microstructure of soil and theory of electrochemical impedance spectroscopy (EIS), an integrated equivalent circuit model and impedance formula for soils were proposed, which contain 6 meaningful resistance and reactance parameters. Considering the conductive properties of soils and dispersion effects, mathematical equations for impedance under various circuit models were deduced and studied. The mathematical expression presents two semicircles for theoretical EIS Nyquist spectrum, in which the center of one semicircle is degraded to simply the equivalent model. Based on the measured parameters of EIS Nyquist spectrum, meaningful soil parameters can easily be determined. Additionally, EIS was used to investigate the soil properties with different water contents along with the mathematical relationships and mechanism between the physical parameters and water content. Magnitude of the impedance decreases with the increase of testing frequency and water content for Bode graphs. The proposed model would help us to better understand the soil microstructure and properties and offer more reasonable explanations for EIS spectra.

In order to simulate and study the mechanism of cement stabilized soils polluted by different contents of magnesium sulfate (MS), a series of tests were conducted on the cemented soil samples, including unconfined compression strength (UCS) tests of blocks, X-ray diffraction (XRD) phase analysis of powder samples, microstructure by scanning electronic microscopy (SEM), element composition by energy dispersive spectrometry (EDS), and pore distribution analysis by Image Processed Plus 6.0 (IPP 6.0) software. The UCS test results show that UCS of cemented soils reaches the peak value when the MS content is 4.5 g/kg. While, the UCS for Sample MS4 having the MS content of 18.0 g/kg is the lowest among all tested samples. Based on the EDS analysis results, Sample MS4 has the greater contents for the three elements, oxygen (O), magnesium (Mg) and sulfur (S), than Sample MS1. From the XRD phase analysis, C-A-S-H (3CaO·Al2O3·3CaSO4·32H2O and 3CaO·Al2O3·CaSO4·18H2O), M-A-H (MgO·Al2O3·H2O), M-S-H (MgO·SiO2·H2O), Mg(OH)2 and CaSO4 phase diffraction peaks are obviously intense due to the chemical action associated with the MS. The pore distribution analysis shows that the hydrated products change the distribution of cemented soil pores and the pores with average diameter (AD) of 2–50 μm play a key role in terms of the whole structure of cemented soil. The microscopic structure of the cemented soil with MS exhibits the intertwined and embedded characteristics between the cement and granular soils from the SEM images of cemented soils. The microstructure analysis shows that the magnesium sulfate acts as the additive, which is beneficial to the soil strength when the MS content is low (i.e., Sample MS2). However, higher MS amount involving a chemical action makes samples crystallize and expand, which is adverse to the UCS of cemented soils (i.e., Sample MS4).

A novel microporous membrane/solvent microextraction (MPMSME) approach was developed in which a piece of microporous filter membrane was used as not only extraction solvent holder but also solid phase extraction unit. Subsequently, high-performance liquid chromatography with an UV detector was conducted. The wide exchange surface and very little organic solvent consumption made this sample pretreatment technology very interesting. The cinnamic acid derivatives were used as model analytes to evaluate the procedure. Parameters that affect the MPMSME such as type of extraction solvent, membrane area (or volumes of extraction solvent), aqueous phase pH, ionic strength, extraction stirring rate, extraction time, and sample volume were investigated and optimized. The enrichment factor (EF) of analyte was defined in MPMSME. Under the optimized conditions, the EFs of cinnamic acid derivatives were 43–144. Good linearities were obtained from 4 to 4,000 ng mL−1 for all the analytes with regression coefficients of between 0.9956 and 0.9977; the limits of quantification were below 0.4 ng mL−1, and satisfactory recoveries (93–106 %) and precisions (0.37–13 %) were also achieved. The experimental results showed that the method was simple, rapid, practical, and effective for preconcentration and determination of the cinnamic acid derivatives in rhizoma typhonii.

An advantageous method based on hollow fiber liposome microscreening (HFLMS) combined with high-performance liquid chromatography (HPLC) has been developed and used in preliminary screening and analysis of biomembrane permeable compounds from herbal medicines (HMs). In the method, a liposome hollow fiber was prepared as a screening tool; permeable compounds that could specifically bind to liposomes were screened from herbal extract to liposome in the pores and lumen of hollow fiber, then permeable compounds were dissociated from liposomes and analyzed by HPLC. The chromatographic separation was applied with a Zorbax Eclipse XDB-C18 column by a gradient elution using acetonitrile, methanol, and phosphoric acid aqueous solution as the mobile phases. In the study, influencing factors of the screened target compounds were investigated and optimized. Under optimum conditions, the surface properties of liposome hollow fibers were characterized, the nonspecific binding between the active center of hollow fiber and the bioactive components were investigated, the repeatability of this method was tested. And eight permeable compounds of flavonoids and anthraquinones from HMs were preliminarily screened and analyzed by HFLMS-HPLC. The results demonstrated that new method is a simple, fast, effective, and reliable method for preliminary screening and analyzing biomembrane permeable ingredients in HMs, and it can be used in screening other permeable compounds in HMs.

In this paper, two methods, organic solvent dispersive liquid–liquid microextraction (OS-DLLME) and ionic liquid dispersive liquid–liquid microextraction (IL-DLLME), coupled with high-performance liquid chromatography have been critically compared and introduced for the analysis of the eight coumarin compounds (psoralen, isopsoralen, bergapten, isobergapten, oxypeucedanin, imperatorin, osthole, and isoimperatorin) in Radix Angelicae Dahuricae samples. Experimental conditions have been investigated for both OS-DLLME and IL-DLLME. Under optimal conditions, the detection limits of the eight coumarin compounds obtained by OS-DLLME and IL-DLLME ranged between 0.002–0.026 ng mL−1 and 0.013–0.66 ng mL−1, respectively. The relative standard deviations (RSDs, n = 9) were lower than 8.7 and 8.4% with enrichment factors in the range of 145–380 and 130–230 folds for OS-DLLME and IL-DLLME, respectively. The results showed that there were no significant deviations between the two DLLME methods for the determination of the eight coumarin compounds. Both methods were simple, fast, efficient, and inexpensive. However, compared with IL-DLLME, the OS-DLLME technique exhibited a higher extraction capacity for the eight target analytes.

Hollow fiber liquid–liquid phase microextraction followed by high-performance liquid chromatography was employed to research the binding of four furocoumarin compounds (psoralen, oxypeucedanin, imperatorin and isoimperatorin) to bovine serum albumin. The results reveal that the percent of drug–protein binding did not rely on the furocoumarins and protein concentrations, and four furocoumarins scarcely competed for protein binding sites. The protein-binding percents of psoralen, oxypeucedanin, imperatorin and isoimperatorin were 55.1 ± 4.5, 14.4 ± 2.4, 44.1 ± 6.7, and 41.3 ± 3.8%, respectively, the numbers of binding sites were 1.2, 1.6, 0.6 and 0.3, and the binding constants were 1,801, 212, 937 and 4,025 L mol−1, respectively. The proposed new approach is simple, rapid, and effective for the study of the interaction between protein and furocoumarin compounds which is either individual or coexistent with the similar ones.