[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.

[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.

Determination of the Pharmacokinetics and Tissue Distribution of Methyl 3,4-Dihydroxybenzoate (MDHB) in Mice Using Liquid Chromatography-Tandem Mass Spectrometry.

Background And Objectives: Methyl 3,4-dihydroxybenzoate (MDHB) has the potential to prevent neurodegenerative diseases (NDDs). The present work aims to reveal the pharmacokinetics and tissue distribution characteristics of MDHB.

Methods: The pharmacokinetics and tissue distribution of MDHB were analyzed using LC-MS/MS after a single intragastric administration (50 to 450 mg/kg) in mice, and samples were collected from five animals at specific time points.

[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.

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.