Fractional vegetation cover (FVC) is a quantitative indicator for vegetation growth conditions and ecosystem change. Clarifying the spatial and temporal trends and driving factors of FVC is an important research content of global and regional ecological environment. Based on Google Earth Engine (GEE) cloud computing platform, we estimated FVC in Heilongjiang Province from 1990 to 2020 using the pixel dichotomous model.
View Article and Find Full Text PDFTo explore the mechanism of extraction and enrichment of three nitrophenol isomers by charge-transfer supramolecular synergistic three-phase microextraction system, a charge transfer supramolecular-mediated hollow fiber liquid-phase microextraction (CTSM-HF-LPME) combined with high-performance liquid chromatography-ultraviolet detector (HPLC-UV) method was established for the determination of real environmental water samples. In this study, the three nitrophenols (NPs) formed charge-transfer supramolecules with electron-rich hollow fibers, which promoted the transport of NPs in the three-phase extraction system and greatly increased the EFs of NPs. The relationships between the EFs of NPs and their solubility, pK, apparent partition coefficient, equilibrium constant, and structural property parameters were investigated and discussed.
View Article and Find Full Text PDFA novel solvent terminated microextraction method based on a natural deep eutectic solvent (L-menthol and lactic acid at a molar ratio of 1:2) coupled with high-performance liquid chromatography was proposed, which was utilized for the separation and enrichment of bisdemethoxycurcumin, demethoxycurcumin and curcumin in Curcumae Longae Rhizoma and turmeric tea. The effects of independent parameters on extraction efficiency were optimized by single-factor analysis. Subsequently, four predominated parameters affecting the extraction procedure, including extractant volume, salt concentration, demulsifier consumption, and demulsification time, were further evaluated by a central composite design.
View Article and Find Full Text PDFIn this study, a vortex-assisted hydrophobic deep eutectic solvent dispersive liquid-phase microextraction was developed and used for the extraction and preconcentration of six main active compounds in Zi-Cao-Cheng-Qi decoction. The deep eutectic solvent, prepared by mixing tetrabutylammonium chloride and hexanoic acid at a molar ratio of 1:1, was added to the sample solution containing the analytes. In the absence of disperser, the extractant was rapidly dispersed into fine droplets by the aid of vortex and adequately contacted with the analytes.
View Article and Find Full Text PDFA reverse micelle mediated dispersive liquid-liquid microextraction (RM-DLLME) combined with high performance liquid chromatography-ultraviolet detector (HPLC-UV) was developed for extraction and determination of 5 A components of teicoplanin (TA, TA, TA, TA, TA) in human plasma, and the mechanism of RM-DLLME was analysed and explored. In this method, 80 µL of the reverse micelle solution of cetylpyridinium chloride/n-hexanol (15 mmol/L) was used as the extraction solvent for the separation, extraction and enrichment of the teicoplanin in plasma sample. All factors affecting the extraction efficiencies of the target analytes, such as the amounts of acetonitrile and chloroform, the type and volume of reverse micelle solution, pH and volume of sample phase, dispersant, salt addition, extraction mode and time, centrifugation rate and time, were investigated and optimized.
View Article and Find Full Text PDFComposite pile foundation has been widely used in ground engineering. This composite pile foundation system has complex pile-soil interactions under seismic loading. The calculation of vertical bearing capacity of composite pile foundation is still an unsolved problem if the soil around piles is partially or completely liquefied under seismic loading.
View Article and Find Full Text PDFSelf-assembled supramolecular dispersive liquid-phase microextraction combined with high-performance liquid chromatography was developed and introduced for simultaneous extraction and determination of the trace level rhein, chrysophanol, and physcion in Rhubarb. Compared with conventional dispersive liquid-phase microextraction, the proposed method used a self-assembled ternary supramolecular consisting of the mixed extraction solvent (heptanol and nonanol) and dispersant (acetone) to achieve high enrichment factors of target analytes. Several factors affecting performance were investigated and optimized, including the mixed extraction solvent, type and volume of the dispersant, the pH of sample phase, salt concentration, shaking time, volume of sample phase, centrifugation time, and rate.
View Article and Find Full Text PDFA novel three-phase hollow fiber liquid-phase microextraction was developed based on reverse micelle as extraction solvent and acceptor phase, and compared with conventional two-phase hollow fiber liquid-phase microextraction. Both procedures were used in the extraction and concentration of four cinnamic acids (caffeic acid, p-hydroxycinnamic acid, ferulic acid, and cinnamic acid) in traditional Chinese medicines prior to high-performance liquid chromatography analysis. Parameters affecting the two procedures were investigated and optimized to obtain the optimum enrichment factors.
View Article and Find Full Text PDFThis study proposed a new ballpoint connector-protected salt-oil-salt liquid phase microextraction for extraction and enrichment of trace rhein and chrysophanol in rhubarb prior to determination of the analytes by high performance liquid chromatography. In this study, a handy ballpoint connector (between ballpoint tip and ink chamber) was used as extraction device, in which its cavity was filled with n-octanol, and the bare n-octanol in its two opening ends was covered with a thin layer of sodium chloride film. The design subtly assembled salt film onto ballpoint connector for extraction and enrichment, which greatly improved the enrichment factors of the target analytes.
View Article and Find Full Text PDFA three-phase hollow-fiber liquid-phase microextraction based on deep eutectic solvent as acceptor phase was developed and coupled with high-performance capillary electrophoresis for the simultaneous extraction, enrichment, and determination of main active compounds (hesperidin, honokiol, shikonin, magnolol, emodin, and β,β'-dimethylacrylshikonin) in a traditional Chinese medicinal formula. In this procedure, two hollow fibers, impregnated with n-heptanol/n-nonanol (7:3, v/v) mixture in wall pores as the extraction phase and a combination (9:1, v/v) of methyltrioctylammonium chloride/glycerol (1:3, n/n) and methanol in lumen as the acceptor phase, were immersed in the aqueous sample phase. The target analytes in the sample solution were first extracted through the organic phase, and further back-extracted to the acceptor phase during the stirring process.
View Article and Find Full Text PDFA sodium dodecyl sulfate sensitized switchable solvent liquid-phase microextraction method was developed and applied to the preconcentration of active alkaloids in Rhizoma coptidis followed by high performance liquid chromatography determination. Before extraction, nonionic triethylamine was converted to its cationic form in the presence of carbon dioxide. Then, the ionic solvent carrying target analytes was once more reverted to its nonionic form by adding sodium hydroxide, as well as phase separation and analytes enrichment were realized simultaneously.
View Article and Find Full Text PDFSichuan Da Xue Xue Bao Yi Xue Ban
March 2017
Objectives: To determine the therapeutic effect and protective mechanism of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) on newborn rats with hypoxia ischemic brain damage (HIBD).
Methods: Umbilical cord (3-4 cm) was collected from a healthy male infant for preparation of hUC-MSCs using explants technique. The hUC-MSCs were cultured and labeled with BrdU.
A novel hollow-fiber liquid-phase microextraction based on oil-in-salt was proposed and introduced for the simultaneous extraction and enrichment of the main active compounds of hesperidin, honokiol, shikonin, magnolol, emodin, and β,β'-dimethylacrylshikonin in a formula of Zi-Cao-Cheng-Qi decoction and the single herb, Fructus Aurantii Immaturus, Cortex Magnoliae Officinalis, Radix et Rhizoma, and Lithospermum erythrorhizon, composing the formula prior to their analysis by high-performance liquid chromatography. The results obtained by the proposed procedure were compared with those obtained by conventional hollow-fiber liquid-phase microextraction, and the proposed procedure mechanism was described. In the procedure, a hollow-fiber segment was first immersed in organic solvent to fill the solvent in the fiber lumen and wall pore, and then the fiber was again immersed into sodium chloride solution to cover a thin salt membrane on the fiber wall pore filling organic solvent.
View Article and Find Full Text PDFA novel graphene/dodecanol floating solidification microextraction followed by HPLC with diode-array detection has been developed to extract trace levels of four cinnamic acid derivatives in traditional Chinese medicines. Several parameters affecting the performance were investigated and optimized. Also, possible microextraction mechanism was analyzed and discussed.
View Article and Find Full Text PDFIn this work, the conduction mechanism of avalanche transistors was demonstrated and the operation condition for generating high-speed pulse using avalanche transistors was illustrated. Based on the above analysis, a high-speed and high-voltage pulse (HHP) generating circuit using avalanche transistors was designed, and its working principle and process were studied. To improve the speed of the output pulse, an approach of reducing the rise time of the leading edge is proposed.
View Article and Find Full Text PDFSichuan Da Xue Xue Bao Yi Xue Ban
November 2015
Objective: To investigate the role of phosphatidylinositol 3 kinase/protein kinase B (PI3K/Akt) signaling pathway for umbilical cord-derived mesenchymal stem cells (UC-MSCs) treating in neonatal rats with hypoxia-ischemia brain damage (HIBD).
Methods: P10 SD rats were divided into sham group, MSCs group, inhibitor (LY 294002) group (LY group) and HIBD group randomly. To establish a neonatal rat model of HIBD, UC-MSCs labeled with Brd U were transplanted into the lateral ventricle of rats.
Sichuan Da Xue Xue Bao Yi Xue Ban
November 2015
Objective: To explore the possible mechanism of berberine improve insulin resistance in skeletal muscle of obese rats.
Methods: Forty Wistar rats were divided into normal control group (NC group, n =10) and high fat food group (HF group, n=30). After the obese model rats established successfully, the rats of NC group (n=10) and HF group (n=10) were sacrificed.
A novel hollow fiber cell fishing with high performance liquid chromatography (HFCF-HPLC) was extended and used to screen flavonoid and anthraquinone active compound groups simultaneously from traditional Chinese medicines (TCMs). In this study, three cells (MCF-7, SGC7901, and MADB-106) were seeded on the inner wall of the hollow fiber employed to screen bioactive components from TCM water decoction. The variables influencing HFCFHPLC, such as cell seeding time, screening stirring rate and time, and active compound concentration, were investigated and optimized.
View Article and Find Full Text PDFObjective: To study the brain protection and the possible mechanism of human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) in neonatal rat model of hypoxic-ischemic brain damage (HIBD).
Methods: Successfully establishing a neonatal rat model of HIBD, hUC-MSCs labeled with BrdU were transplanted into the lateral ventricle 24 hours after HIBD. The number of apoptotic cells and the expression of Caspase-3 were detected by TUNEL and Western blot respectively at 24 and 48 hours after transplantation.
Zhonghua Fu Chan Ke Za Zhi
September 2013
Objective: To study the effects of oxytocin antagonists-atosiban on pregnancy outcome after thaw embryo transfer (TET).
Methods: Between Jul. and Dec.
A novel technique, ionic liquid-water-organic solvent three phase microextraction (ILWOS-3p-ME) was developed and introduced for simultaneous preconcentration and determination of flavonoids and anthraquinones in Chinese herbal formula and its preparations. This technique was performed in one step by using a syringe. High performance liquid chromatography with an UV-detector (HPLC/UV) was subsequently conducted.
View Article and Find Full Text PDFGuang Pu Xue Yu Guang Pu Fen Xi
April 2012
Based on the characteristic of high speed line scanning for CCD in transient spectrum detection, a method of transient spectrum detection with array CCD is presented. The high speed line scanning with array CCD was realized by changing the mode of charge transfer. In order to explore the feasibility of this method, a fast detection system of single point based on linear CCD was designed and fabricated.
View Article and Find Full Text PDFZhonghua Fu Chan Ke Za Zhi
February 2012
Objective: To study the influence of EmbryoGlue on the implantation of embryo and pregnancy outcome in vitro fertilization (IVF)-embryo transfer (ET).
Methods: From August 2010 to January 2011, 243 infertile patients in Reproductive Medical Center of Tianjin Medical University General Hospital who underwent IVF or intracytoplasmic sperm injection (ICSI) were divided into two groups, including 129 cases used EmbryoGlue as the embryo transfer medium in experimental group and 114 cases used G-2 as embryo transfer medium in control group. Pregnancy outcome were compared between two groups.
Guang Pu Xue Yu Guang Pu Fen Xi
November 2011
Based on the spectral characteristic of the detonation temperature, the present paper presents a measurement system of transient multi-wavelength pyrometry with the theory of multi-wavelength thermometry. The FPGA was applied as the hardware developing platform and the high-speed linear CCD was utilized. Each module was controlled by FPGA to achieve the process of real-time data acquisition, storage and transmission.
View Article and Find Full Text PDFZhonghua Fu Chan Ke Za Zhi
August 2007
Objective: To investigate the influence of transfer distance from the fundus on clinical pregnancy rate and implantation rate in in vitro fertilization and embryo transfer.
Methods: A total of 98 patients (108 cycles) undergoing ultrasound-guided embryo transfer were divided into two groups according to the distance between the tip of catheter and the uterine fundus: group A: > or = 5 - < 10 mm, group B: > or = 10 - < or = 15 mm.
Results: Clinical pregnancy rate and implantation rate were significantly higher in group B compared with group A [44 % (23/52) vs 25% (14/56), 24% (28/115) vs 14% (17/121), P < 0.