[Comparison of the Geochemical Characteristics of Karst Springs of a Vertically Zoned Climate Region under Human Activity: A Case of Shuifang Spring and Bitan Spring in the Jinfo Mountain Area, Chongqing].

To investigate the hydrochemical variation of karstic groundwaters in a vertically zoned climate region affected by human activity, Shuifang Spring and Bitan Spring in the Jinfo Mountain area of Chongqing were selected as a study site. Based on the differences between the natural state and intensity of human activity of these two springs, their hydrogeochemical characteristics and the controlling factors on karstic groundwaters were analyzed by means of independent sample tests, the Gibbs graphic method, principle component analysis (PCA), and geochemical susceptivity analysis. The results show that differences in karst development in the vertical climatic zone leads to higher total ion concentrations in Bitan Spring than in Shuifang Spring.

Coupled hydrogeochemical evaluation of a vulnerable karst aquifer impacted by septic effluent in a protected natural area.

Karst aquifers are highly vulnerable to pollution from human activities. Among sources of these contaminants, septic tank effluent can easily pollute karst aquifers, especially concentrated inputs such as those, for example, from tourist hotels. However, the impacts of septic effluent from relatively large, concentrated inputs on karst aquifers have seldom been assessed previously and therefore provide the focus of this study.

[Nitrate-Nitrogen Pollution Sources of an Underground River in Karst Agricultural Area Using N and O Isotope Technique].

The objectives of this study were to reveal the sources of nitrate and the ratio of karst in an agricultural basin based on a N and O isotope technique and quantitative calculation of the IsoSource model. From May to October 2017, six sampling points in the Qingmuguan river basin, Chongqing, were monitored every 24 d. Results showed that there was a great risk of nitrate pollution in the underground river system, because most NO-N concentrations of the sampling points exceeded the threshold.

Pericyte-targeting prodrug overcomes tumor resistance to vascular disrupting agents.

Blood vessels in the tumor periphery have high pericyte coverage and are resistant to vascular disrupting agents (VDAs). VDA treatment resistance leads to a viable peripheral tumor rim that contributes to treatment failure and disease recurrence. Here, we provide evidence to support a hypothesis that shifting the target of VDAs from tumor vessel endothelial cells to pericytes disrupts tumor peripheral vessels and the viable rim, circumventing VDA treatment resistance.

Spatial-temporal distribution and potential ecological risk assessment of nonylphenol and octylphenol in riverine outlets of Pearl River Delta, China.

The aquatic environments of the Pearl River Delta in Southern China are subjected to contamination with various industrial chemicals from local industries. In this paper, the occurrence, seasonal variation and spatial distribution of alkylphenol octylphenol (OP) and nonylphenol (NP) in river surface water and sediments in the runoff outlets of the Pearl River Delta were investigated. NP and OP were detected in all water and sediment samples and their mean concentrations in surface water during the dry season ranged from 810 to 3366 ng/L and 85.

[Chemical constituents of Berchemia lineate].

Objective: To investigate the chemical constituents of the roots of Berchemia lineate as a medicinal plant of Yao nationality in China.

Methods: Compounds were isolated by various column chromatography and elucidated by physicochemical and spectral analysis.

Results: Nine compounds were isolated from the 95% ethanol extract of the roots of Berchemia lineate and their structures were identified as palmitic acid (1), octadecanoic acid (2), beta-sitosterol (3), stigmasterol (4), fernenol (5), chrysophanol (6), physcion (7), floribundiquinone D (8), 2-acetylphyscion(9) respectively.

Rapid and sensitive LC-MS/MS method for the determination of metoprolol in Beagle dog plasma with a simple protein precipitation treatment and its pharmacokinetic applications.

A rapid LC-MS/MS method with good accuracy and sensitivity was developed and validated for the pharmacokinetics study of metoprolol (MP) in beagle dogs. The plasma samples were simply precipitated by methanol and then analyzed by LC-MS/MS. An Ultimate XB-C₁₈ column (150 × 2.

A new pregnane glycoside and oligosaccharide from Parabarium huaitingii.

Two new compounds, along with two known compounds, were isolated from the barks of Parabarium huaitingii, and their structures were determined as 5α-pregn-6-ene-3β,17α,20(S)-triol-20-O-β-d-digitoxopyranoside (1), cymaropyranurolactone 4-O-β-d-digitalopyranosyl-(1 → 4)-O-β-d-cymaropyranosyl-(1 → 4)-O-β-d-oleandropyranosyl-(1 → 4)-O-β-d-cymaropyranoside (2), 3β,17α,20(S)-trihydroxy-5α-pregn-6-ene (3), and 5α-pregn-6-ene-3β,17α,20(S)-triol-3-O-β-d-digitalopyranoside (4) by spectroscopic methods.

[Studies on the chemical constituents from Cissus pteroclada].

Objective: To study the chemical constituents of Yao Medicine Cissus pteroclada.

Methods: The compounds were isolated and purified by column chromatography with silica gel, TLC and recrystallization. Their structures were elucidated on the basis of physicochemical properties and spectra analysis.

[Sodium dichlorinated isocyanuric acid and trichloroisocyanuric acid for removing cells of Phaeochystis globosa].

Removal and control of Phaeochystis globosa cells by sodium dichlorinated isocyanuric acid and tri-chloroisocyanuric acid were studied. Removal efficiency of the two algaecides was contrasted and removal mechanism was also discussed. The results suggest both of the algaecides have excellent ability to remove and control Phaeochystis globosa cells.

[Povidone-iodine and isothiozolone for removing red tide algae Phaeoecystis globosa].

Studies on the removal and control of red tide algae Phaeoecystis globosa by povidone-iodine and isothiozolone algaecide showed that Phaeoecystis globosa could be killed and controlled by povidone-iodine and isothiozolone. The effective concentration of povidone-iodine was 30 mg.L-1, and that of isothiozolone was 0.